title: Breast cancer

text: In the United States, 10 to 20 percent of women with breast cancer or ovarian cancer have a first- or second-degree relative with one of these diseases. Men with breast cancer have an even higher likelihood. The familial tendency to develop these cancers is called hereditary breast–ovarian cancer syndrome. The best known of these, the "BRCA" mutations, confer a lifetime risk of breast cancer of between 60 and 85 percent and a lifetime risk of ovarian cancer of between 15 and 40 percent. Some mutations associated with cancer, such as "p53", "BRCA1" and "BRCA2", occur in mechanisms to correct errors in DNA. These mutations are either inherited or acquired after birth. Presumably, they allow further mutations, which allow uncontrolled division, lack of attachment, and metastasis to distant organs. However, there is strong evidence of residual risk variation that goes well beyond hereditary "BRCA" gene mutations between carrier families. This is caused by unobserved risk factors. This implicates environmental and other causes as triggers for breast cancers. The inherited mutation in "BRCA1" or "BRCA2" genes can interfere with repair of DNA cross links and DNA double strand breaks (known functions of the encoded protein). These carcinogens cause DNA damage such as DNA cross links and double strand breaks that often require repairs by pathways containing BRCA1 and BRCA2. However, mutations in "BRCA" genes account for only 2 to 3 percent of all breast cancers. Levin "et al." say that cancer may not be inevitable for all carriers of "BRCA1" and "BRCA2" mutations. About half of hereditary breast–ovarian cancer syndromes involve unknown genes. Furthermore, certain latent viruses, may decrease the expression of the "BRCA1" gene and increase the risk of breast tumours.


title: Breast cancer

text: GATA-3 directly controls the expression of estrogen receptor (ER) and other genes associated with epithelial differentiation, and the loss of GATA-3 leads to loss of differentiation and poor prognosis due to cancer cell invasion and metastasis.


title: Breast cancer

text: Most types of breast cancer are easy to diagnose by microscopic analysis of a sample – or biopsy – of the affected area of the breast. Also, there are types of breast cancer that require specialized lab exams.


title: Breast cancer

text: The two most commonly used screening methods, physical examination of the breasts by a healthcare provider and mammography, can offer an approximate likelihood that a lump is cancer, and may also detect some other lesions, such as a simple cyst. When these examinations are inconclusive, a healthcare provider can remove a sample of the fluid in the lump for microscopic analysis (a procedure known as fine needle aspiration, or fine needle aspiration and cytology, FNAC) to help establish the diagnosis. A needle aspiration can be performed in a healthcare provider's office or clinic. A local anesthetic may be used to numb the breast tissue to prevent pain during the procedure, but may not be necessary if the lump is not beneath the skin. A finding of clear fluid makes the lump highly unlikely to be cancerous, but bloody fluid may be sent off for inspection under a microscope for cancerous cells. Together, physical examination of the breasts, mammography, and FNAC can be used to diagnose breast cancer with a good degree of accuracy.


title: Breast cancer

text: Other options for biopsy include a core biopsy or vacuum-assisted breast biopsy, which are procedures in which a section of the breast lump is removed; or an excisional biopsy, in which the entire lump is removed. Very often the results of physical examination by a healthcare provider, mammography, and additional tests that may be performed in special circumstances (such as imaging by ultrasound or MRI) are sufficient to warrant excisional biopsy as the definitive diagnostic and primary treatment method.


title: Breast cancer

text: Breast cancers are classified by several grading systems. Each of these influences the prognosis and can affect treatment response. Description of a breast cancer optimally includes all of these factors.


title: Breast cancer

text: Breast cancer screening refers to testing otherwise-healthy women for breast cancer in an attempt to achieve an earlier diagnosis under the assumption that early detection will improve outcomes. A number of screening tests have been employed including clinical and self breast exams, mammography, genetic screening, ultrasound, and magnetic resonance imaging.


title: Breast cancer

text: A clinical or self breast exam involves feeling the breast for lumps or other abnormalities. Clinical breast exams are performed by health care providers, while self-breast exams are performed by the person themselves. Evidence does not support the effectiveness of either type of breast exam, as by the time a lump is large enough to be found it is likely to have been growing for several years and thus soon be large enough to be found without an exam. Mammographic screening for breast cancer uses X-rays to examine the breast for any uncharacteristic masses or lumps. During a screening, the breast is compressed and a technician takes photos from multiple angles. A general mammogram takes photos of the entire breast, while a diagnostic mammogram focuses on a specific lump or area of concern.


title: Breast cancer

text: A number of national bodies recommend breast cancer screening. For the average woman, the U.S. Preventive Services Task Force and American College of Physicians recommends mammography every two years in women between the ages of 50 and 74, the Council of Europe recommends mammography between 50 and 69 with most programs using a 2-year frequency, while the European Commission recommends mammography from 45 to 75 every 2 to 3 years, and in Canada screening is recommended between the ages of 50 and 74 at a frequency of 2 to 3 years. The American Cancer Society also endorses that women ages 40 and older receive mammograms annually. These task force reports point out that in addition to unnecessary surgery and anxiety, the risks of more frequent mammograms include a small but significant increase in breast cancer induced by radiation.


title: Breast cancer

text: The Cochrane collaboration (2013) states that the best quality evidence neither demonstrates a reduction in cancer specific, nor a reduction in all cause mortality from screening mammography. When less rigorous trials are added to the analysis there is a reduction in mortality due to breast cancer of 0.05% (a decrease of 1 in 2000 deaths from breast cancer over 10 years or a relative decrease of 15% from breast cancer). Screening over 10 years results in a 30% increase in rates of over-diagnosis and over-treatment (3 to 14 per 1000) and more than half will have at least one falsely positive test. This has resulted in the view that it is not clear whether mammography screening does more good or harm. Cochrane states that, due to recent improvements in breast cancer treatment, and the risks of false positives from breast cancer screening leading to unnecessary treatment, "it therefore no longer seems beneficial to attend for breast cancer screening" at any age. Whether MRI as a screening method has greater harms or benefits when compared to standard mammography is not known.


title: Breast cancer

text: Women can reduce their risk of breast cancer by maintaining a healthy weight, reducing alcohol use, increasing physical activity, and breast-feeding. These modifications might prevent 38% of breast cancers in the US, 42% in the UK, 28% in Brazil, and 20% in China. The benefits with moderate exercise such as brisk walking are seen at all age groups including postmenopausal women. High levels of physical activity reduce the risk of breast cancer by about 14%. Strategies that encourage regular physical activity and reduce obesity could also have other benefits, such as reduced risks of cardiovascular disease and diabetes. A study that included data from 130,957 women of European ancestry found "strong evidence that greater levels of physical activity and less sedentary time are likely to reduce breast cancer risk, with results generally consistent across breast cancer subtypes".


title: Breast cancer

text: The American Cancer Society and the American Society of Clinical Oncology advised in 2016 that people should eat a diet high in vegetables, fruits, whole grains, and legumes. High intake of citrus fruit has been associated with a 10% reduction in the risk of breast cancer. Marine omega-3 polyunsaturated fatty acids appear to reduce the risk. High consumption of soy-based foods may reduce risk.


title: Breast cancer

text: Removal of both breasts before any cancer has been diagnosed or any suspicious lump or other lesion has appeared (a procedure known as "prophylactic bilateral mastectomy" or "risk reducing mastectomy") may be considered in women with BRCA1 and BRCA2 mutations, which are associated with a substantially heightened risk for an eventual diagnosis of breast cancer. Evidence is not strong enough to support this procedure in anyone but women at the highest risk. BRCA testing is recommended in those with a high family risk after genetic counseling. It is not recommended routinely. This is because there are many forms of changes in BRCA genes, ranging from harmless polymorphisms to obviously dangerous frameshift mutations. The effect of most of the identifiable changes in the genes is uncertain. Testing in an average-risk person is particularly likely to return one of these indeterminate, useless results. Removing the second breast in a person who has breast cancer (contralateral risk‐reducing mastectomy or CRRM) may reduce the risk of cancer in the second breast, however, it is unclear if removing the second breast in those who have breast cancer improves survival.


title: Breast cancer

text: The selective estrogen receptor modulators reduce the risk of breast cancer but increase the risk of thromboembolism and endometrial cancer. There is no overall change in the risk of death. They are thus not recommended for the prevention of breast cancer in women at average risk but it is recommended they be offered for those at high risk and over the age of 35. The benefit of breast cancer reduction continues for at least five years after stopping a course of treatment with these medications. Aromatase inhibitors (such as exemestane and anasatrozole) may be more effective than selective estrogen receptor modulators (such as tamoxifen) at reducing breast cancer risk and they are not associated with an increased risk of endometrial cancer and thromboembolism.


title: Breast cancer

text: The management of breast cancer depends on various factors, including the stage of the cancer and the person's age. Treatments are more aggressive when the cancer is more advanced or there is a higher risk of recurrence of the cancer following treatment.


title: Breast cancer

text: Breast cancer is usually treated with surgery, which may be followed by chemotherapy or radiation therapy, or both. A multidisciplinary approach is preferable. Hormone receptor-positive cancers are often treated with hormone-blocking therapy over courses of several years. Monoclonal antibodies, or other immune-modulating treatments, may be administered in certain cases of metastatic and other advanced stages of breast cancer, although this range of treatment is still being studied.


title: Breast cancer

text: Surgery involves the physical removal of the tumour, typically along with some of the surrounding tissue. One or more lymph nodes may be biopsied during the surgery; increasingly the lymph node sampling is performed by a sentinel lymph node biopsy.


title: Breast cancer

text: Once the tumour has been removed, if the person desires, breast reconstruction surgery, a type of plastic surgery, may then be performed to improve the aesthetic appearance of the treated site.


title: Breast cancer

text: Alternatively, women use breast prostheses to simulate a breast under clothing, or choose a flat chest. Nipple prosthesis can be used at any time following the mastectomy.


title: Breast cancer

text: Medications used after and in addition to surgery are called adjuvant therapy. Chemotherapy or other types of therapy prior to surgery are called neoadjuvant therapy. Aspirin may reduce mortality from breast cancer when used with other treatments.


title: Breast cancer

text: There are currently three main groups of medications used for adjuvant breast cancer treatment: hormone-blocking agents, chemotherapy, and monoclonal antibodies.


title: Breast cancer

text: Some breast cancers require estrogen to continue growing. They can be identified by the presence of estrogen receptors (ER+) and progesterone receptors (PR+) on their surface (sometimes referred to together as hormone receptors). These ER+ cancers can be treated with drugs that either block the receptors, e.g. tamoxifen, or alternatively block the production of estrogen with an aromatase inhibitor, e.g. anastrozole or letrozole. The use of tamoxifen is recommended for 10 years. Tamoxifen increases the risk of postmenopausal bleeding, endometrial polyps, hyperplasia, and endometrial cancer; using tamoxifen with an intrauterine system releasing levonorgestrel might increase vaginal bleeding after one to two years, but reduces somewhat endometrial polyps and hyperplasia, but not necessarily endometrial cancer. Letrozole is recommended for five years.


title: Breast cancer

text: Aromatase inhibitors are only suitable for women after menopause; however, in this group, they appear better than tamoxifen. This is because the active aromatase in postmenopausal women is different from the prevalent form in premenopausal women, and therefore these agents are ineffective in inhibiting the predominant aromatase of premenopausal women. Aromatase inhibitors should not be given to premenopausal women with intact ovarian function (unless they are also on treatment to stop their ovaries from working). CDK inhibitors can be used in combination with endocrine or aromatase therapy.


title: Breast cancer

text: Chemotherapy is predominantly used for cases of breast cancer in stages 2–4, and is particularly beneficial in estrogen receptor-negative (ER-) disease. The chemotherapy medications are administered in combinations, usually for periods of 3–6 months. One of the most common regimens, known as "AC", combines cyclophosphamide with doxorubicin. Sometimes a taxane drug, such as docetaxel, is added, and the regime is then known as "CAT". Another common treatment is cyclophosphamide, methotrexate, and fluorouracil (or "CMF"). Most chemotherapy medications work by destroying fast-growing and/or fast-replicating cancer cells, either by causing DNA damage upon replication or by other mechanisms. However, the medications also damage fast-growing normal cells, which may cause serious side effects. Damage to the heart muscle is the most dangerous complication of doxorubicin, for example.


title: Breast cancer

text: Trastuzumab, a monoclonal antibody to HER2, has improved the five-year disease free survival of stage 1–3 HER2-positive breast cancers to about 87% (overall survival 95%). Between 25% and 30% of breast cancers overexpress the HER2 gene or its protein product, and overexpression of HER2 in breast cancer is associated with increased disease recurrence and worse prognosis. Trastuzumab, however, is very expensive, and its use may cause serious side effects (approximately 2% of people who receive it develop significant heart damage). Another antibody pertuzumab prevents HER2 dimerization and is recommended together with trastuzumab and chemotherapy in severe disease.


title: Breast cancer

text: Radiotherapy is given after surgery to the region of the tumour bed and regional lymph nodes, to destroy microscopic tumour cells that may have escaped surgery. When given intraoperatively as targeted intraoperative radiotherapy, it may also have a beneficial effect on tumour microenvironment. Radiation therapy can be delivered as external beam radiotherapy or as brachytherapy (internal radiotherapy). Conventionally radiotherapy is given "after" the operation for breast cancer. Radiation can also be given at the time of operation on the breast cancer. Radiation can reduce the risk of recurrence by 50–66% (1/2 – 2/3 reduction of risk) when delivered in the correct dose and is considered essential when breast cancer is treated by removing only the lump (Lumpectomy or Wide local excision). In early breast cancer, partial breast irradiation does not give the same cancer control in the breast as treating the whole breast and may cause worse side effects.


title: Breast cancer

text: Care after primary breast cancer treatment, otherwise called 'follow-up care', can be intensive involving regular laboratory tests in asymptomatic people to try to achieve earlier detection of possible metastases. A review has found that follow-up programs involving regular physical examinations and yearly mammography alone are as effective as more intensive programs consisting of laboratory tests in terms of early detection of recurrence, overall survival and quality of life.


title: Breast cancer

text: Multidisciplinary rehabilitation programmes, often including exercise, education and psychological help, may produce short-term improvements in functional ability, psychosocial adjustment and social participation in people with breast cancer.


title: Breast cancer

text: Upper limb problems such as shoulder and arm pain, weakness and restricted movement are a common side effect after radiotherapy or breast cancer surgery. According to research in the UK, an exercise programme started 7–10 days after surgery can reduce upper limb problems.


title: Breast cancer

text: The stage of the breast cancer is the most important component of traditional classification methods of breast cancer, because it has a greater effect on the prognosis than the other considerations. Staging takes into consideration size, local involvement, lymph node status and whether metastatic disease is present. The higher the stage at diagnosis, the poorer the prognosis. The stage is raised by the invasiveness of disease to lymph nodes, chest wall, skin or beyond, and the aggressiveness of the cancer cells. The stage is lowered by the presence of cancer-free zones and close-to-normal cell behaviour (grading). Size is not a factor in staging unless the cancer is invasive. For example, ductal carcinoma in situ (DCIS) involving the entire breast will still be stage zero and consequently an excellent prognosis with a 10-year disease free survival of about 98%.


title: Breast cancer

text: The breast cancer grade is assessed by comparison of the breast cancer cells to normal breast cells. The closer to normal the cancer cells are, the slower their growth and the better the prognosis. If cells are not well differentiated, they will appear immature, will divide more rapidly, and will tend to spread. Well differentiated is given a grade of 1, moderate is grade 2, while poor or undifferentiated is given a higher grade of 3 or 4 (depending upon the scale used). The most widely used grading system is the Nottingham scheme.


title: Breast cancer

text: Younger women with an age of less than 40 years or women over 80 years tend to have a poorer prognosis than post-menopausal women due to several factors. Their breasts may change with their menstrual cycles, they may be nursing infants, and they may be unaware of changes in their breasts. Therefore, younger women are usually at a more advanced stage when diagnosed. There may also be biological factors contributing to a higher risk of disease recurrence for younger women with breast cancer.


title: Breast cancer

text: Not all people with breast cancer experience their illness in the same manner. Factors such as age can have a significant impact on the way a person copes with a breast cancer diagnosis. Premenopausal women with estrogen-receptor positive breast cancer must confront the issues of early menopause induced by many of the chemotherapy regimens used to treat their breast cancer, especially those that use hormones to counteract ovarian function.


title: Breast cancer

text: In women with non-metastatic breast cancer, psychological interventions such as cognitive behavioral therapy can have positive effects on outcomes such as anxiety, depression and mood disturbance. Physical activity interventions may also have beneficial effects on health related quality of life, anxiety, fitness and physical activity in women with breast cancer following adjuvant therapy.


title: Breast cancer

text: Worldwide, breast cancer is the most-common invasive cancer in women. Along with lung cancer, breast cancer is the most commonly diagnosed cancer, with 2.09 million cases each in 2018. Breast cancer affects 1 in 7 (14%) of women worldwide. (The most common form of cancer is non-invasive non-melanoma skin cancer; non-invasive cancers are generally easily cured, cause very few deaths, and are routinely excluded from cancer statistics.) Breast cancer comprises 22.9% of invasive cancers in women and 16% of all female cancers. In 2012, it comprised 25.2% of cancers diagnosed in women, making it the most-common female cancer.


title: Breast cancer

text: In 2008, breast cancer caused 458,503 deaths worldwide (13.7% of cancer deaths in women and 6.0% of all cancer deaths for men and women together). Lung cancer, the second most-common cause of cancer-related deaths in women, caused 12.8% of cancer deaths in women (18.2% of all cancer deaths for men and women together).


title: Breast cancer

text: The incidence of breast cancer varies greatly around the world: it is lowest in less-developed countries and greatest in the more-developed countries. In the twelve world regions, the annual age-standardized incidence rates per 100,000 women are as follows: 18 in Eastern Asia, 22 in South Central Asia and sub-Saharan Africa, 26 in South-Eastern Asia, 26, 28 in North Africa and Western Asia, 42 in South and Central America, 42, 49 in Eastern Europe, 56 in Southern Europe, 73 in Northern Europe, 74 in Oceania, 78 in Western Europe, and 90 in North America. Metastatic breast cancer affects between 19% (United States) and 50% (parts of Africa) of women with breast cancer.


title: Breast cancer

text: The number of cases worldwide has significantly increased since the 1970s, a phenomenon partly attributed to the modern lifestyles. Breast cancer is strongly related to age with only 5% of all breast cancers occurring in women under 40 years old. There were more than 41,000 newly diagnosed cases of breast cancer registered in England in 2011, around 80% of these cases were in women age 50 or older. Based on U.S. statistics in 2015 there were 2.8 million women affected by breast cancer. In the United States, the age-adjusted incidence of breast cancer per 100,000 women rose from around 102 cases per year in the 1970s to around 141 in the late-1990s, and has since fallen, holding steady around 125 since 2003. However, age-adjusted deaths from breast cancer per 100,000 women only rose slightly from 31.4 in 1975 to 33.2 in 1989 and have since declined steadily to 20.5 in 2014.


title: Breast cancer

text: Multiple primary tumours can arise in different sites (as opposed to a single tumour spreading). These tumours can occur in both breasts (bilateral tumours), in different quadrants of a single breast (multi-centric cancer), or separate tumours within a single breast quadrant (multi-focal cancer).


title: Breast cancer

text: Incidence of multi-centric and multi-focal breast cancers (MMBC) is increasing, partly due to improving mammography technology. Incidence of MMBC is reported between 9 and 75% in high income countries, depending on criteria used. For instance, China reported that only 2% of patients are defined as MMBC. The reason for this difference is due to lack of uniformity in diagnosis. Therefore, standardised method and criteria should be made in order to define the incidence of MMBC correctly.


title: Breast cancer

text: Mutations in tumour suppressor genes such as BRCA1 and BRCA2, the PI3K/AKT/mTOR pathway and PTEN can be related to formation of multiple primary breast cancers. Diagnosis occurs via the same modalities as other breast cancers.


title: Breast cancer

text: Mastectomy is the standard surgical treatment for multi centric breast cancer patients. Double lumpectomies, also labelled as breast conservative therapy (BCT), is an alternative and preferred surgical treatment to mastectomy for early stage multi centric breast cancer patients. The procedure of double lumpectomies involves the surgical ablation of the cancerous tumour foci and the surrounding breast tissues in different quadrant of the same breast. The benefits of double lumpectomies are the avoidance of breast reconstruction surgery and minimal breast scarring. However, this surgical treatment is not preferable for patients with over two breast tumours within the same breast due to difficulty in removing all cancer cells. Patients with multiple primary breast tumours may receive treatments such as chemotherapy, radiotherapy and breast reconstruction surgery for the same indications as other breast cancer patients.


title: Breast cancer

text: Because of its visibility, breast cancer was the form of cancer most often described in ancient documents. Because autopsies were rare, cancers of the internal organs were essentially invisible to ancient medicine. Breast cancer, however, could be felt through the skin, and in its advanced state often developed into fungating lesions: the tumour would become necrotic (die from the inside, causing the tumour to appear to break up) and ulcerate through the skin, weeping fetid, dark fluid.


title: Breast cancer

text: The oldest discovered evidence of breast cancer is from Egypt and dates back 4200 years, to the Sixth Dynasty. The study of a woman's remains from the necropolis of Qubbet el-Hawa showed the typical destructive damage due to metastatic spread. The Edwin Smith Papyrus describes eight cases of tumours or ulcers of the breast that were treated by cauterization. The writing says about the disease, "There is no treatment." For centuries, physicians described similar cases in their practices, with the same conclusion. Ancient medicine, from the time of the Greeks through the 17th century, was based on humoralism, and thus believed that breast cancer was generally caused by imbalances in the fundamental fluids that controlled the body, especially an excess of black bile. Alternatively it was seen as divine punishment.


title: Breast cancer

text: Mastectomy for breast cancer was performed at least as early as AD 548, when it was proposed by the court physician Aetios of Amida to Theodora. It was not until doctors achieved greater understanding of the circulatory system in the 17th century that they could link breast cancer's spread to the lymph nodes in the armpit. In the early 18th century the French surgeon Jean Louis Petit performed total mastectomies that included removing the axillary lymph nodes, as he recognized that this reduced recurrence. Petit's work built on the methods of the surgeon Bernard Peyrilhe, who in the 17th century additionally removed the pectoral muscle underlying the breast, as he judged that this greatly improved the prognosis. But poor results and the considerable risk to the patient meant that physicians did not share the opinion of surgeons such as Nicolaes Tulp, who in the 17th century proclaimed "the sole remedy is a timely operation". The eminent surgeon Richard Wiseman documented in the mid 17th century that following 12 mastectomies, two patients died during the operation, eight patients died shortly after the operation from progressive cancer and only two of the 12 patients were cured. Physicians were conservative in the treatment they prescribed in the early stages of breast cancer. Patients were treated with a mixture of detox purges, blood letting and traditional remedies that were supposed to lower acidity, such as the alkaline arsenic.


title: Breast cancer

text: When in 1664 Anne of Austria was diagnosed with breast cancer, the initial treatment involved compresses saturated with hemlock juice. When the lumps increased the King's physician commenced a treatment with arsenic ointments. The royal patient died 1666 in atrocious pain. Each failing treatment for breast cancer led to the search for new treatments, spurring a market in remedies that were advertised and sold by quacks, herbalists, chemists and apothecaries. The lack of anesthesia and antiseptics made mastectomy a painful and dangerous ordeal. In the 18th century, a wide variety of anatomical discoveries were accompanied by new theories about the cause and growth of breast cancer. The investigative surgeon John Hunter claimed that neural fluid generated breast cancer. Other surgeons proposed that milk within the mammary ducts led to cancerous growths. Theories about trauma to the breast as cause for malignant changes in breast tissue were advanced. The discovery of breast lumps and swellings fueled controversies about hard tumours and whether lumps were benign stages of cancer. Medical opinion about necessary immediate treatment varied. The surgeon Benjamin Bell advocated removal of the entire breast, even when only a portion was affected.


title: Breast cancer

text: Breast cancer was uncommon until the 19th century, when improvements in sanitation and control of deadly infectious diseases resulted in dramatic increases in lifespan. Previously, most women had died too young to have developed breast cancer. In 1878, an article in "Scientific American" described historical treatment by pressure intended to induce local ischemia in cases when surgical removal were not possible. William Stewart Halsted started performing radical mastectomies in 1882, helped greatly by advances in general surgical technology, such as aseptic technique and anesthesia. The Halsted radical mastectomy often involved removing both breasts, associated lymph nodes, and the underlying chest muscles. This often led to long-term pain and disability, but was seen as necessary to prevent the cancer from recurring. Before the advent of the Halsted radical mastectomy, 20-year survival rates were only 10%; Halsted's surgery raised that rate to 50%.


title: Breast cancer

text: Breast cancer staging systems were developed in the 1920s and 1930s to determining the extent to which a cancer has developed by growing and spreading. The first case-controlled study on breast cancer epidemiology was done by Janet Lane-Claypon, who published a comparative study in 1926 of 500 breast cancer cases and 500 controls of the same background and lifestyle for the British Ministry of Health. Radical mastectomies remained the standard of care in the USA until the 1970s, but in Europe, breast-sparing procedures, often followed by radiation therapy, were generally adopted in the 1950s. In 1955 George Crile Jr. published "Cancer and Common Sense" arguing that cancer patients needed to understand available treatment options. Crile became a close friend of the environmentalist Rachel Carson, who had undergone a Halsted radical mastectomy in 1960 to treat her malign breast cancer. The US oncologist Jerome Urban promoted superradical mastectomies, taking even more tissue, until 1963, when the ten-year survival rates proved equal to the less-damaging radical mastectomy. Carson died in 1964 and Crile went on to published a wide variety of articles, both in the popular press and in medical journals, challenging the widespread used of the Halsted radical mastectomy. In 1973 Crile published "What Women Should Know About the Breast Cancer Controversy". When in 1974 Betty Ford was diagnosed with breast cancer, the options for treating breast cancer were openly discussed in the press. During the 1970s, a new understanding of metastasis led to perceiving cancer as a systemic illness as well as a localized one, and more sparing procedures were developed that proved equally effective.


title: Breast cancer

text: In the 1980s and 1990s, thousands of women who had successfully completed standard treatment then demanded and received high-dose bone marrow transplants, thinking this would lead to better long-term survival. However, it proved completely ineffective, and 15–20% of women died because of the brutal treatment. The 1995 reports from the Nurses' Health Study and the 2002 conclusions of the Women's Health Initiative trial conclusively proved that hormone replacement therapy significantly increased the incidence of breast cancer.


title: Breast cancer

text: Before the 20th century, breast cancer was feared and discussed in hushed tones, as if it were shameful. As little could be safely done with primitive surgical techniques, women tended to suffer silently rather than seeking care. When surgery advanced, and long-term survival rates improved, women began raising awareness of the disease and the possibility of successful treatment. The "Women's Field Army", run by the American Society for the Control of Cancer (later the American Cancer Society) during the 1930s and 1940s was one of the first organized campaigns. In 1952, the first peer-to-peer support group, called "Reach to Recovery", began providing post-mastectomy, in-hospital visits from women who had survived breast cancer.


title: Breast cancer

text: The breast cancer movement of the 1980s and 1990s developed out of the larger feminist movements and women's health movement of the 20th century. This series of political and educational campaigns, partly inspired by the politically and socially effective AIDS awareness campaigns, resulted in the widespread acceptance of second opinions before surgery, less invasive surgical procedures, support groups, and other advances in care.


title: Breast cancer

text: A pink ribbon is the most prominent symbol of breast cancer awareness. Pink ribbons, which can be made inexpensively, are sometimes sold as fundraisers, much like poppies on Remembrance Day. They may be worn to honor those who have been diagnosed with breast cancer, or to identify products that the manufacturer would like to sell to consumers that are interested in breast cancer. In the 1990s breast cancer awareness campaigns were launched by US based corporations. As part of these cause related marketing campaigns corporations donated to a variety of breast cancer initiatives for every pink ribbon product that was purchased.> "The Wall Street Journal" noted "that the strong emotions provoked by breast cancer translate to a company's bottom line". While many US corporations donated to existing breast cancer initiatives others such as Avon established their own breast cancer foundations on the back of pink ribbon products.


title: Breast cancer

text: Wearing or displaying a pink ribbon has been criticized by the opponents of this practice as a kind of slacktivism, because it has no practical positive effect. It has also been criticized as hypocrisy, because some people wear the pink ribbon to show good will towards women with breast cancer, but then oppose these women's practical goals, like patient rights and anti-pollution legislation. Critics say that the feel-good nature of pink ribbons and pink consumption distracts society from the lack of progress on preventing and curing breast cancer. It is also criticized for reinforcing gender stereotypes and objectifying women and their breasts.< In 2002 Breast Cancer Action launched the "Think Before You Pink" campaign against pinkwashing to target businesses that have co-opted the pink campaign to promote products that cause breast cancer, such as alcoholic beverages.


title: Breast cancer

text: In her 2006 book "Pink Ribbons, Inc.: Breast Cancer and the Politics of Philanthropy" Samantha King claimed that breast cancer has been transformed from a serious disease and individual tragedy to a market-driven industry of survivorship and corporate sales pitch. In 2010 Gayle Sulik argued that the primary purposes or goals of breast cancer culture are to maintain breast cancer's dominance as the pre-eminent women's health issue, to promote the appearance that society is doing something effective about breast cancer, and to sustain and expand the social, political, and financial power of breast cancer activists. In the same year Barbara Ehrenreich published an opinion piece in "Harper's Magazine", lamenting that in breast cancer culture, breast cancer therapy is viewed as a rite of passage rather than a disease. To fit into this mold, the woman with breast cancer needs to normalize and feminize her appearance, and minimize the disruption that her health issues cause anyone else. Anger, sadness, and negativity must be silenced. As with most cultural models, people who conform to the model are given social status, in this case as cancer survivors. Women who reject the model are shunned, punished and shamed. The culture is criticized for treating adult women like little girls, as evidenced by "baby" toys such as pink teddy bears given to adult women.


title: Breast cancer

text: In 2009 the US science journalist Christie Aschwanden criticized that the emphasis on breast cancer screening may be harming women by subjecting them to unnecessary radiation, biopsies, and surgery. One-third of diagnosed breast cancers might recede on their own. Screening mammography efficiently finds non-life-threatening, asymptomatic breast cancers and precancers, even while overlooking serious cancers. According to the cancer researcher H. Gilbert Welch, screening mammography has taken the "brain-dead approach that says the best test is the one that finds the most cancers" rather than the one that finds dangerous cancers.


title: Breast cancer

text: In 2002 it was noted that as a result of breast cancer's high visibility, the statistical results can be misinterpreted, such as the claim that one in eight women will be diagnosed with breast cancer during their lives – a claim that depends on the unrealistic assumption that no woman will die of any other disease before the age of 95. By 2010 the breast cancer survival rate in Europe was 91% at one years and 65% at five years. In the USA the five-year survival rate for localized breast cancer was 96.8%, while in cases of metastases it was only 20.6%. Because the prognosis for breast cancer was at this stage relatively favorable, compared to the prognosis for other cancers, breast cancer as cause of death among women was 13.9% of all cancer deaths. The second most common cause of death from cancer in women was lung cancer, the most common cancer worldwide for men and women. The improved survival rate made breast cancer the most prevalent cancer in the world. In 2010 an estimated 3.6 million women worldwide have had a breast cancer diagnosis in the past five years, while only 1.4 million male or female survivors from lung cancer were alive.


title: Breast cancer

text: There are ethnic disparities in the mortality rates for breast cancer as well as in breast cancer treatment. Breast cancer is the most prevalent cancer affecting women of every ethnic group in the United States. Breast cancer incidence among black women aged 45 and older is higher than that of white women in the same age group. White women aged 60–84 have higher incidence rates of breast cancer than Black women. Despite this, Black women at every age are more likely to succumb to breast cancer.


title: Breast cancer

text: Breast cancer treatment has improved greatly in recent years, but black women are still less likely to obtain treatment compared to white women. Risk factors such as socioeconomic status, late-stage, or breast cancer at diagnosis, genetic differences in tumour subtypes, differences in health care access all contribute to these disparities. Socioeconomic determinants affecting the disparity in breast cancer illness include poverty, culture, as well as social injustice. In Hispanic women, the incidence of breast cancer is lower than in non-Hispanic women but is often diagnosed at a later stage than white women with larger tumors.


title: Breast cancer

text: Black women are usually diagnosed with breast cancer at a younger age than white women. The median age of diagnosis for Black women is 59, in comparison to 62 in White women. The incidence of breast cancer in Black women has increased by 0.4% per year since 1975 and 1.5% per year among Asian/Pacific Islander women since 1992. Incidence rates were stable for non-Hispanic White, Hispanics, and Native women. The five-year survival rate is noted to be 81% in Black women and 92% in White women. Chinese and Japanese women have the highest survival rates.


title: Breast cancer

text: Poverty is a major driver for disparities related to breast cancer. Low-income women are less likely to undergo breast cancer screening and thus are more likely to have a late-stage diagnosis. Ensuring women of all ethnic groups receive equitable health care can positively affect these disparities.


title: Breast cancer

text: Pregnancy at an early age decreases the risk of developing breast cancer later in life. The risk of breast cancer also declines with the number of children a woman has. Breast cancer then becomes more common in the 5 or 10 years following pregnancy but then becomes less common than among the general population. These cancers are known as postpartum breast cancer and have worse outcomes including an increased risk of distant spread of disease and mortality. Other cancers found during or shortly after pregnancy appear at approximately the same rate as other cancers in women of a similar age.


title: Breast cancer

text: Diagnosing new cancer in a pregnant woman is difficult, in part because any symptoms are commonly assumed to be a normal discomfort associated with pregnancy. As a result, cancer is typically discovered at a somewhat later stage than average in many pregnant or recently pregnant women. Some imaging procedures, such as MRIs (magnetic resonance imaging), CT scans, ultrasounds, and mammograms with fetal shielding are considered safe during pregnancy; some others, such as PET scans are not.


title: Breast cancer

text: Treatment is generally the same as for non-pregnant women. However, radiation is normally avoided during pregnancy, especially if the fetal dose might exceed 100 cGy. In some cases, some or all treatments are postponed until after birth if the cancer is diagnosed late in the pregnancy. Early deliveries to speed the start of treatment are not uncommon. Surgery is generally considered safe during pregnancy, but some other treatments, especially certain chemotherapy drugs given during the first trimester, increase the risk of birth defects and pregnancy loss (spontaneous abortions and stillbirths). Elective abortions are not required and do not improve the likelihood of the mother surviving or being cured.


title: Breast cancer

text: Radiation treatments may interfere with the mother's ability to breastfeed her baby because it reduces the ability of that breast to produce milk and increases the risk of mastitis. Also, when chemotherapy is being given after birth, many of the drugs pass through breast milk to the baby, which could harm the baby.


title: Breast cancer

text: Regarding future pregnancy among breast cancer survivors, there is often fear of cancer recurrence. On the other hand, many still regard pregnancy and parenthood to represent normality, happiness and life fulfillment.


title: Breast cancer

text: In breast cancer survivors, non-hormonal birth control methods such as the copper intrauterine device (IUD) should be used as first-line options. Progestogen-based methods such as depot medroxyprogesterone acetate, IUD with progestogen or progestogen only pills have a poorly investigated but possible increased risk of cancer recurrence, but may be used if positive effects outweigh this possible risk.


title: Breast cancer

text: In breast cancer survivors, it is recommended to first consider non-hormonal options for menopausal effects, such as bisphosphonates or selective estrogen receptor modulators (SERMs) for osteoporosis, and vaginal estrogen for local symptoms. Observational studies of systemic hormone replacement therapy after breast cancer are generally reassuring. If hormone replacement is necessary after breast cancer, estrogen-only therapy or estrogen therapy with an intrauterine device with progestogen may be safer options than combined systemic therapy.


title: Breast cancer

text: Treatments are being evaluated in clinical trials. This includes individual drugs, combinations of drugs, and surgical and radiation techniques Investigations include new types of targeted therapy, cancer vaccines, oncolytic virotherapy, gene therapy and immunotherapy.


title: Breast cancer

text: The latest research is reported annually at scientific meetings such as that of the American Society of Clinical Oncology, San Antonio Breast Cancer Symposium, and the St. Gallen Oncology Conference in St. Gallen, Switzerland. These studies are reviewed by professional societies and other organizations, and formulated into guidelines for specific treatment groups and risk category.


title: Breast cancer

text: Fenretinide, a retinoid, is also being studied as a way to reduce the risk of breast cancer. In particular, combinations of ribociclib plus endocrine therapy have been the subject of clinical trials.


title: Breast cancer

text: A 2019 review found moderate certainty evidence that giving people antibiotics before breast cancer surgery helped to prevent surgical site infection (SSI). Further study is required to determine the most effective antibiotic protocol and use in women undergoing immediate breast reconstruction.


title: Breast cancer

text: As of 2014 cryoablation is being studied to see if it could be a substitute for a lumpectomy in small cancers. There is tentative evidence in those with tumours less than 2 centimeters. It may also be used in those in who surgery is not possible. Another review states that cryoablation looks promising for early breast cancer of small size.


title: Breast cancer

text: Part of the current knowledge on breast carcinomas is based on in vivo and in vitro studies performed with cell lines derived from breast cancers. These provide an unlimited source of homogenous self-replicating material, free of contaminating stromal cells, and often easily cultured in simple standard media. The first breast cancer cell line described, BT-20, was established in 1958. Since then, and despite sustained work in this area, the number of permanent lines obtained has been strikingly low (about 100). Indeed, attempts to culture breast cancer cell lines from primary tumours have been largely unsuccessful. This poor efficiency was often due to technical difficulties associated with the extraction of viable tumour cells from their surrounding stroma. Most of the available breast cancer cell lines issued from metastatic tumours, mainly from pleural effusions. Effusions provided generally large numbers of dissociated, viable tumour cells with little or no contamination by fibroblasts and other tumour stroma cells.


title: Breast cancer

text: Many of the currently used BCC lines were established in the late 1970s. A very few of them, namely MCF-7, T-47D, MDA-MB-231 and SK-BR-3, account for more than two-thirds of all abstracts reporting studies on mentioned breast cancer cell lines, as concluded from a Medline-based survey.


title: Breast cancer

text: Clinically, the most useful metabolic markers in breast cancer are the estrogen and progesterone receptors that are used to predict response to hormone therapy. New or potentially new markers for breast cancer include BRCA1 and BRCA2 to identify people at high risk of developing breast cancer, HER-2, and SCD1, for predicting response to therapeutic regimens, and urokinase plasminogen activator, PA1-1 and SCD1 for assessing prognosis.


title: Julian Nagelsmann

text: Julian Nagelsmann (born 23 July 1987) is a German professional football manager and former football player who is the head coach of Bayern Munich. Prior to managing Bayern, he managed 1899 Hoffenheim and RB Leipzig.


title: Julian Nagelsmann

text: Known for his versatility with formations, maintaining possession, and implementing "gegenpress", Nagelsmann is considered to be one of the best young managers in world football.


title: Julian Nagelsmann

text: Nagelsmann was born on 23 July 1987 in Landsberg am Lech, Bavaria. He played for FC Augsburg and 1860 Munich at youth level, and was the captain of Munich's U17 team. In the 2006–07 season, he was part of the second team but could not play a single match due to injuries. Nagelsmann returned to Augsburg for the 2007–08 season coached by Thomas Tuchel, but injured his knee and meniscus for the second time, damaging the cartilage. As a result, he decided to end his footballing career at the age of 20. He had already assisted his head coach Thomas Tuchel as a scout in the first half of 2008. He studied business administration in university for four semesters until he transferred to sports science. Then he concentrated on coaching, returning to his former club 1860 Munich as an assistant to Alexander Schmidt for Munich's U17 team from 2008 to 2010.


title: Julian Nagelsmann

text: Nagelsmann joined 1899 Hoffenheim's youth academy in 2010 and coached different youth teams in the following years. He was an assistant coach during Hoffenheim's 2012–13 season, and up until 11 February 2016, was coaching the club's U19 team. He coached Hoffenheim's U19 "junior team" to win the 2013–14 Under 19 Bundesliga title. During his time as assistant coach, goalkeeper Tim Wiese nicknamed Nagelsmann "Mini-Mourinho."


title: Julian Nagelsmann

text: Nagelsmann was appointed head coach of 1899 Hoffenheim on 27 October 2015. He was due to begin his tenure at the beginning of the 2016–17 season. He was given a three-year contract. At the time of his appointment, Nagelsmann was 28, and the youngest coach in Bundesliga history. He was to be the successor for Huub Stevens, who had replaced Markus Gisdol the previous year. On 10 February 2016, Stevens resigned as head coach due to health problems, and Nagelsmann's tenure as head coach was brought forward by the Hoffenheim board a day later.


title: Julian Nagelsmann

text: When Nagelsmann took over the club in February 2016, Hoffenheim were 17th in the table, 7 points from the safety of 15th spot and facing relegation. Under Nagelsmann they avoided relegation by winning 7 of their remaining 14 matches and finished a point above the relegation playoff spot. Their good run of play continued in the 2016–17 Bundesliga season, where they finished 4th in the table and qualified for the UEFA Champions League for the first time in their history.


title: Julian Nagelsmann

text: On 9 June 2017, Hoffenheim extended the contract of Nagelsmann until 2021. On 21 June 2018, Hoffenheim announced that Nagelsmann would be leaving the club at the end of the 2018–19 season. He oversaw his 100th league game as Hoffenheim coach on 19 January 2019, in a 3–1 defeat to Bayern Munich. In doing so, he became the youngest ever Bundesliga coach to reach the 100 match milestone.


title: Julian Nagelsmann

text: On 21 June 2019, RB Leipzig announced that Nagelsmann would be their coach from the 2019–20 season and signed a four-year contract which would expire in 2023. Nagelsmann won his first Bundesliga match as RB Leipzig coach against FC Union Berlin 4–0, he also led Leipzig to a 1–1 draw against FC Bayern Munich. On match-day 10 Leipzig won against Mainz 8–0. Nagelsmann faced his former club Hoffenheim on match-day 14 and won 3–1 against them.


title: Julian Nagelsmann

text: On 10 March 2020, following Leipzig's 4–0 win against Tottenham Hotspur, Nagelsmann became the youngest coach in history to win a UEFA Champions League knockout tie.


title: Julian Nagelsmann

text: On 13 August 2020, RB Leipzig defeated Spanish side Atlético Madrid 2–1 in the quarter-finals, meaning Leipzig would progress to the Champions League semi-finals for the first time in their history. Nagelsmann became the youngest coach in history, therefore, to coach a side in the semi-finals.


title: Julian Nagelsmann

text: On 18 August 2020, RB Leipzig played against Paris Saint-Germain in the Champions League semi-finals, where Nagelsmann faced his former boss during his time at Augsburg, Thomas Tuchel. However, RB Leipzig lost 3–0 to Paris Saint-Germain.


title: Julian Nagelsmann

text: In the 2020–21 season, RB Leipzig finished second in the Bundesliga and lost the DFB-Pokal Final 4–1 against Borussia Dortmund.


title: Julian Nagelsmann

text: On 27 April 2021, Bayern Munich appointed Nagelsmann as head coach on a five-year deal, effective from 1 July 2021, replacing Hansi Flick for a world record managerial transfer fee of €25 Million. Nagelsmann's first competitive match was a 1–1 draw against Borussia Mönchengladbach in the Bundesliga.


title: Julian Nagelsmann

text: In Nagelsmann's first win with Bayern, he won his first title as a coach in Bayern's 3-1 victory over Borussia Dortmund in the 2021 DFL-Supercup.


title: Julian Nagelsmann

text: On 24 August 2021, Nagelsmann led Bayern to a 12–0 victory against Bremer SV during the first round of the 2021–22 DFB-Pokal. The scoreline was their biggest win in 24 years, since their 16–1 victory against DJK Waldberg in the DFB Cup in August 1997.


title: Julian Nagelsmann

text: On 12 April 2022, Nagelsmann and his team were knocked out of the UEFA Champions League quarter-finals, 2–1 on aggregate by Villarreal. On 23 April 2022, he won his second title, his first Bundesliga title, with three matches to spare.


title: Julian Nagelsmann

text: Nagelsmann married his childhood sweetheart Verena in 2018. Nagelsmann is a vegetarian. He said there were two reasons, most important for him is animal welfare, the second is environmental protection.


title: Kate Pierson

text: Catherine Elizabeth Pierson (born April 27, 1948) is an American singer, lyricist, and founding member of the B-52's. She plays guitar, bass and various keyboard instruments. In the B-52s, she has performed alongside Cindy Wilson, Fred Schneider, Ricky Wilson, and Keith Strickland. In the early years, as well as being a vocalist, Pierson was the main keyboard player and performed on a keyboard bass during live shows and on many of the band's recordings, taking on a role usually filled by a bass guitar player, which differentiated the band from their contemporaries. This, along with Pierson's distinctive wide-ranging singing voice, remains a trademark of the B-52's' unique sound. Pierson has also collaborated with many other artists including The Ramones, Iggy Pop and R.E.M. Pierson possesses a soprano vocal range.


title: Kate Pierson

text: In February 2015, Pierson released her first solo album, "Guitars and Microphones", featuring material co-written by Sia. She later released the non-album single "Better Not Sting the Bee", and on April 15, 2016, she released a cover of "Venus" as a single.


title: Kate Pierson

text: Pierson briefly attended Wheaton College in Wheaton, Illinois before transferring to Boston University, where she earned a journalism degree. She then traveled around Europe for a time in the 1970's, including six months working as a barmaid in "The Anson" pub in Wallsend, UK before returning to the U.S. and moving to Athens, Georgia, where she lived on a farm and earned a living as a paste-up artist in the type shop of the local newspaper.


title: Kate Pierson

text: Pierson met up with the other members of what would become the B-52s while living in Athens, Georgia. The band formed in October 1976 and played a few parties before heading to New York to play some shows. Eventually, Pierson and the other band members began commuting between Athens and New York, playing gigs.


title: Kate Pierson

text: She is the owner of Kate's Lazy Desert in Landers, California, Kate's Lazy Cabin in Woodstock, New York, and Kate's Lazy Meadow in Mount Tremper, New York, a rustic modern lodge in New York's Catskill Mountains. She operates the businesses with her wife Monica Coleman, whom she married on August 3, 2015.


title: AC power plugs and sockets

text: AC power plugs and sockets connect electric equipment to the alternating current (AC) mains electricity power supply in buildings and at other sites. Electrical plugs and sockets differ from one another in voltage and current rating, shape, size, and connector type. Different standard systems of plugs and sockets are used around the world.


title: AC power plugs and sockets

text: Plugs and sockets for portable appliances became available in the 1880s, to replace connections to light sockets with wall-mounted outlets. A proliferation of types developed for both convenience and protection from electrical injury. Today there are about 20 types in common use around the world, and many obsolete socket types are found in older buildings. Coordination of technical standards has allowed some types of plug to be used across large regions to facilitate trade in electrical appliances, and for the convenience of travellers and consumers of imported electrical goods.


title: AC power plugs and sockets

text: Some multi-standard sockets allow use of several types of plug; improvised or unapproved adaptors between incompatible sockets and plugs may not provide the full safety and performance of an approved socket-plug combination.


title: AC power plugs and sockets

text: A plug is the movable connector attached to an electrically operated device, and the socket is fixed on equipment or a building structure and connected to an energised electrical circuit. The plug is a "male" connector, often with protruding pins that match the openings and "female" contacts in a socket. Some plugs have female contacts that are used only for an earth ground connection. Some plugs have built-in fuses for safety.


title: AC power plugs and sockets

text: To reduce the risk of electric shock, plug and socket systems have safety features in addition to the recessed contacts of the energised socket.


title: AC power plugs and sockets

text: A socket may be surrounded by a decorative or protective cover which may be integral with the socket.


title: AC power plugs and sockets

text: Single-phase sockets have two current-carrying connections to the power supply circuit, and may also have a third pin for a safety connection to earth ground. Depending on the supply system, one or both current-carrying connections may have significant voltage to earth ground.


title: AC power plugs and sockets

text: When commercial electric power was first introduced in the 1880s, it was used primarily for lighting. Other portable appliances (such as vacuum cleaners, electric fans, smoothing irons, and curling-tong heaters) were connected to light-bulb sockets.


title: AC power plugs and sockets

text: As early as 1885 a two-pin plug and wall socket format was available on the British market. By about 1910 the first three-pin earthed (grounded) plugs appeared. Over time other safety improvements were gradually introduced to the market. The earliest national standard for plug and wall socket forms was set in 1915.


title: AC power plugs and sockets

text: Designs of plugs and sockets have gradually developed to reduce the risk of electric shock and fire. Plugs are shaped to prevent finger contact with live parts. Sockets may be recessed and plugs designed to fit closely within the recess to reduce risk of a user's fingers contacting the live pins. Contact pins may be sheathed with insulation over part of their length, so as to reduce exposure of energized metal during insertion or removal of the socket. Sockets may have automatic shutters to stop foreign objects from being inserted into energized contacts. Some types can also include fuses and switches.


title: AC power plugs and sockets

text: A third contact for a connection to earth is intended to protect against insulation failure of the connected device. Some early unearthed plug and socket types were revised to include an earthing pin or phased out in favour of earthed types. The plug is often designed so that the earth ground contact connects before the energized circuit contacts.


title: AC power plugs and sockets

text: The assigned IEC appliance class is governed by the requirement for earthing or equivalent protection. Class I equipment requires an earth contact in the plug and socket, while Class II equipment is unearthed and protects the user with double insulation.


title: AC power plugs and sockets

text: Where a "neutral" conductor exists in supply wiring, polarisation of the plug can improve safety by preserving the distinction in the equipment. For example, appliances may ensure that switches interrupt the line side of the circuit, or can connect the shell of a screw-base lampholder to neutral to reduce electric shock hazard. In some designs, polarised plugs cannot be mated with non-polarised sockets. Wiring systems where both circuit conductors have a significant potential with respect to earth do not benefit from polarised plugs.


title: AC power plugs and sockets

text: "Universal" or "multi-standard" sockets are intended to accommodate plugs of various types. In some jurisdictions, they violate safety standards for sockets.


title: AC power plugs and sockets

text: Safety advocates, the United States Army, and a manufacturer of sockets point out a number of safety issues with universal socket and adapters, including voltage mismatch, exposure of live pins, lack of proper earth ground connection, or lack of protection from overload or short circuit. Universal sockets may not meet technical standards for durability, plug retention force, temperature rise of components, or other performance requirements, as they are outside the scope of national and international technical standards.


title: AC power plugs and sockets

text: A technical standard may include compatibility of a socket with more than one form of plug. The Thai dual socket is specified in figure 4 of TIS 166-2549 and is designed to accept Thai plugs, and also Type A, B, and C plugs. Chinese dual sockets have both an unearthed socket complying with figure 5 of GB 1002-2008 (both flat pin and 4.8 mm round pin), and an earthed socket complying with figure 4 of GB 1002-2008. Both Thai and Chinese dual sockets also physically accept plugs normally fitted to 120 V appliances (e.g. 120 V rated NEMA 1-15 ungrounded plugs). This can cause an electrical incompatibility, since both states normally supply residential power only at 220 V.


title: AC power plugs and sockets

text: Plugs and power cords have a rated voltage and current assigned to them by the manufacturer. Using a plug or power cord that is inappropriate for the load may be a safety hazard. For example, high-current equipment can cause a fire when plugged into an extension cord with a current rating lower than necessary. Sometimes the cords used to plug in dual voltage 120 V / 240 V equipment are rated only for 125 V, so care must be taken by travellers to use only cords with an appropriate voltage rating.


title: AC power plugs and sockets

text: So that manufacturers need not build many similar appliances differing only in the type of plug fitted, a common strategy is to provide an IEC 60320 inlet on the appliance and a detachable power cord (mains flex lead) and appropriate plug. The appliance need only to be tested to the power inlet. Some appliances have a switch for selection of voltage.


title: AC power plugs and sockets

text: Extension cords (extension leads) are used for temporary connections when a socket is not within convenient reach of an appliance's power lead. A power strip with multiple sockets may also have a switch, surge voltage protection, or over-current protection.


title: AC power plugs and sockets

text: Special purpose sockets may be found in residential, industrial, commercial or institutional buildings. Examples of systems using special purpose sockets include:


title: AC power plugs and sockets

text: Special-purpose sockets may be labelled or coloured to identify a reserved use of a system, or may have keys or specially shaped pins to prevent use of unintended equipment.


title: AC power plugs and sockets

text: National wiring regulations sometimes prohibit the use of sockets adjacent to water taps, etc. A special socket, with an isolation transformer, may allow electric razors to be used near a sink. Because the isolation transformer is of low rating, such outlets are not suitable to operate higher-powered appliances such as hair dryers.


title: AC power plugs and sockets

text: An IEC standard 61558-2-5, adopted by CENELEC and as a national standard in some countries, describes one type of shaver supply unit. Shaver sockets may accept multiple two-pin plug types including Europlug (Type C), Australian (Type I) and BS 4573. The isolation transformer often includes a 115 V output accepting two-pin US plugs (Type A). Shaver supply units must also be current limited, IEC 61558-2-5 specifies a minimum rating of 20 VA and maximum of 50 VA. Sockets are marked with a shaver symbol, and may also say "shavers only."


title: AC power plugs and sockets

text: Isolation transformers and dedicated NEMA 1-15 shaver receptacles were once standard installation practice in North America, but now a GFCI receptacle is used instead. This provides the full capacity of a standard receptacle but protects the user of a razor or other appliance from leakage current.


title: AC power plugs and sockets

text: The International Electrotechnical Commission (IEC) maintains a guide with letter designations for generally compatible types of plugs, which expands on earlier guides published by the United States Department of Commerce. This is a "de facto" naming standard and guide to travellers. Some letter types correspond to several current ratings or different technical standards, so the letter does not uniquely identify a plug and socket within the type family, nor guarantee compatibility. Physical compatibility of the plug and socket does not ensure correct voltage, frequency, or current capacity. Not all plug and socket families have letters in the IEC guide, but those that have are noted in this article, as are some additional letters commonly used by retail vendors.


title: AC power plugs and sockets

text: In Europe, CENELEC publishes a list of approved plug and socket technical standards used in the member countries.


title: AC power plugs and sockets

text: The plug and socket system used in Class 1 applications in Argentina is defined by IRAM standards. These two standards are; IRAM 2073 "Two pole plugs with earthing contact for domestic and similar purposes, rated 10 A and 20 A, 250 V AC" and IRAM 2071 "Two pole socket – outlets with earthing contact for 10 A and 20 A, 250 V AC., for fixed installations." The plug and socket system is similar in appearance to the Australian and Chinese plugs. It has an earthing pin and two flat current-carrying pins forming an inverted V-shape (120°). The flat pins for the 10 A version measure and for the 20 A version, and are set at 30° to the vertical at a nominal pitch of . The pin length is the same as in the Chinese version. The earthing pin length is for the 10 A version and for the 20 A version. On the plugs, the pole length is for the 10 A version and for the 20 A version. The most important difference from the Australian plug is that the Argentinian plug is wired with the live and neutral contacts reversed.


title: AC power plugs and sockets

text: In Brazil, similar plugs and sockets are still commonly used in old installations for high-power appliances like air conditioners, dishwashers, and household ovens. Although being often called "Argentinian plug," it is actually based on the American NEMA 10-20 standard, and is incompatible with Argentinian IRAM plugs. Since Brazil adopted the NBR 14136 standard which includes a 20 A version, the original motivation to use the NEMA 10-20 plug has ceased to exist.


title: AC power plugs and sockets

text: This Australian/New Zealand standard is used in Australia, New Zealand, Fiji, Tonga, Solomon Islands, and Papua New Guinea. It defines a plug with an earthing pin, and two flat current-carrying pins which form an inverted V-shape. The flat pins measure and are set at 30° to the vertical at a nominal pitch of . Australian and New Zealand wall sockets (locally often referred to as "power points") almost always have switches on them for extra safety, as in the UK. An unearthed version of this plug with two angled power pins but no earthing pin is used with double-insulated appliances, but the sockets always include an earth contact.


title: AC power plugs and sockets

text: There are several AS/NZS 3112 plug variants, including ones with larger or differently shaped pins used for devices drawing 15, 20, 25 and 32 A. These sockets accept plugs of equal or lower current rating, but not higher. For example, a 10 A plug will fit all sockets but a 20 A plug will fit only 20, 25 and 32 A sockets. In New Zealand, PDL 940 "tap-on" or "piggy-back" plugs are available which allow a second 10 A plug to be fitted to the rear of the plug. In Australia these piggy-back plugs are now available only on pre-made extension leads.


title: AC power plugs and sockets

text: Australia's standard plug/socket system was originally codified as standard C112 (floated provisionally in 1937, and adopted as a formal standard in 1938), which was based on a design patented by Harvey Hubbell and was superseded by AS 3112 in 1990. The requirement for insulated pins was introduced in the 2004 revision. The current version is "AS/NZS 3112:2011, Approval and test specification – Plugs and socket-outlets".


title: AC power plugs and sockets

text: Brazil, which had been using mostly Europlugs, and NEMA 1-15 and NEMA 5-15 standards, adopted a (non-compliant) variant of IEC 60906-1 as the national standard in 1998 under specification NBR 14136 (revised in 2002). These are used for both 220-volt and 127-volt regions of the country, despite the IEC 60906-2 recommendation that NEMA 5-15 be used for 120 V connections. There are two types of sockets and plugs in NBR 14136: one for 10 A, with a 4.0 mm pin diameter, and another for 20 A, with a 4.8 mm pin diameter. This differs from IEC 60906-1 which specifies a pin diameter of 4.5 mm and a rating of 16 A. NBR 14136 does not require shutters on the apertures, a further aspect of non-compliance with IEC 60906-1. NBR 14136 was not enforced in that country until 2007, when its adoption was made optional for manufacturers. It became compulsory on 1 January 2010.


title: AC power plugs and sockets

text: Few private houses in Brazil have an earthed supply, so even if a three-pin socket is present it is not safe to assume that all three terminals are actually connected. Most large domestic appliances were sold with the option to fit a flying earth tail to be locally earthed, but many consumers were unsure how to use this and so didn't connect it. The new standard has an earth pin, which in theory eliminates the need for the flying earth tail.


title: AC power plugs and sockets

text: BS 546, "Two-pole and earthing-pin plugs, socket-outlets and socket-outlet adaptors for AC (50-60 Hz) circuits up to 250V" describes four sizes of plug rated at 2 A, 5 A (Type D), 15 A (Type M) and 30 A. The plugs have three round pins arranged in a triangle, with the larger top pin being the earthing pin. The plugs are polarised and unfused. Plugs are non-interchangeable between current ratings. Introduced in 1934, the BS 546 type has mostly been displaced in the UK by the BS 1363 standard. According to the IEC, some 40 countries use Type D and 15 countries use Type M. Some, such as India and South Africa, use standards based on BS 546.


title: AC power plugs and sockets

text: BS 1363 "13 A plugs, socket-outlets, adaptors and connection units" is the main plug and socket type used in the United Kingdom. According to the IEC it is also used in over 50 countries worldwide. Some of these countries have national standards based on BS 1363, including: Ireland, Malaysia, Malta, Singapore, Bahrain, Sri Lanka and Saudi Arabia.


title: AC power plugs and sockets

text: This plug has three rectangular pins forming an isosceles triangle. The BS 1363 plug has a fuse rated to protect its flexible cord from overload and consequent fire risk. Modern appliances may only be sold with a fuse of the appropriate size pre-installed.


title: AC power plugs and sockets

text: The United Kingdom, Ireland, and Malta, use the BS 4573 two-pin plug and socket for electric shavers and toothbrushes. The plug has insulated sleeves on the pins. Although similar to the Europlug Type C, the diameter and spacing of the pins are slightly different and hence it will not fit into a Schuko socket. There are, however, two-pin sockets and adaptors which will accept both BS 4573 and Europlugs.


title: AC power plugs and sockets

text: The "International Commission on the Rules for the Approval of Electrical Equipment" (IECEE) was a standards body which published "Specification for plugs and socket-outlets for domestic and similar purposes" as CEE Publication 7 in 1951. It was last updated by Modification 4 in March 1983. CEE 7 consists of general specifications and standard sheets for specific connectors.


title: AC power plugs and sockets

text: Standard plugs and sockets based on two round pins with centres spaced at 19 mm are in use in Europe, most of which are listed in IEC/TR 60083 "Plugs and socket-outlets for domestic and similar general use standardized in member countries of IEC." EU countries each have their own regulations and national standards; for example, some require child-resistant shutters, while others do not. CE marking is neither applicable nor permitted on plugs and sockets.


title: AC power plugs and sockets

text: CEE 7/1 unearthed sockets accept CEE 7/2 round plugs with pins. Because they have no earth connections they have been or are being phased out in most countries. Some countries still permit their use in dry areas. Older sockets are so shallow that it is possible to accidentally touch the live pins of a plug. CEE 7/1 sockets also accept CEE 7/4, CEE 7/6 and CEE 7/7 plugs without providing an earth connection. The earthed CEE 7/3 and CEE 7/5 sockets do not allow insertion of CEE 7/2 unearthed round plugs.


title: AC power plugs and sockets

text: The CEE 7/3 socket and CEE 7/4 plug are commonly called "Schuko", an abbreviation for "Schutzkontakt", "Protective contact" to earth ("Schuko" itself is a registered trademark of a German association established to own the term). The socket has a circular recess with two round holes and two earthing clips that engage before live pin contact is made. The pins are . The Schuko system is unpolarised, allowing live and neutral to be reversed. The socket accepts Europlugs and CEE 7/17 plugs. It is rated at 16 A. The current German standards are DIN 49441 and DIN 49440. The standard is used in Germany and several other European countries and on other continents. Some countries require child-proof socket shutters; the DIN 49440 standard does not have this requirement.


title: AC power plugs and sockets

text: The plug is used in most countries of Europe, Asia, and Africa, as well as in the countries of Peru, Chile and Uruguay. The few European countries not using it (or not using it predominantly) are Denmark, Switzerland, UK, Italy and Ireland.


title: AC power plugs and sockets

text: French standard NF C 61-314 defines the CEE 7/5 socket and CEE 7/6 plug, (and also includes CEE 7/7, 7/16 and 7/17 plugs). The socket has a circular recess with two round holes. The round earth pin projecting from the socket connects before the energized contacts touch. The earth pin is centred between the apertures, offset by . The plug has two round pins measuring , spaced apart and with an aperture for the socket's projecting earth pin. This standard is also used in Belgium, Poland, the Czech Republic, Slovakia and some other countries.


title: AC power plugs and sockets

text: Although the plug is polarised, CEE 7 does not define the placement of the live and neutral and there is no universally observed standard.


title: AC power plugs and sockets

text: CEE 7/2 and 7/4 plugs are not compatible with the CEE 7/5 socket because of the round earthing pin permanently mounted in the socket.


title: AC power plugs and sockets

text: The CEE 7/7 plug has earthing contacts to connect to either the CEE 7/3 socket or the CEE 7/5 socket. It is polarised when used with a French CEE 7/5 socket, but can be inserted two ways into a CEE 7/3 socket. The plug is rated at 16 A. Appliances are sold with non-rewireable CEE 7/7 plugs attached. This plug can be inserted into a Danish Type K socket, but the earth contact will not connect.


title: AC power plugs and sockets

text: The CEE 7/16 unearthed plug is used for unearthed appliances. It has two round 4 by 19 mm (0.157 by 0.748 in) pins, rated at 2.5 A. There are two variants.


title: AC power plugs and sockets

text: Alternative I is a round plug with cutouts to make it compatible with CEE 7/3 and CEE 7/5 sockets. (The similar-appearing CEE 7/17 has larger pins and a higher current rating.) This alternative is seldom used.


title: AC power plugs and sockets

text: Alternative II, popularly known as the Europlug, is a flat 2.5 A-rated plug defined by Cenelec standard EN 50075 and national equivalents. The Europlug is not rewirable and must be supplied with a flexible cord. It can be inserted in either direction, so line and neutral are connected arbitrarily. To improve contact with socket parts the Europlug has slightly flexible pins which converge toward their free ends.


title: AC power plugs and sockets

text: There is no socket defined to accept only the Europlug. Instead, the Europlug fits a range of sockets in common use in Europe. These sockets, including the CEE 7/1, CEE 7/3 (German/"Schuko"), CEE 7/5 (French). Most Israeli, Swiss, Danish and Italian sockets, were designed to accept pins of various diameters, mainly 4.8 mm, but also 4.0 mm and 4.5 mm, and are usually fed by final circuits with either 10 A or 16 A overcurrent protection devices.


title: AC power plugs and sockets

text: UK shaver sockets are designed to accept BS 4573 shaver plugs while also accepting Europlugs. In this configuration, the connection supply is only rated at 200 mA. It is not permissible within the UK for the shaver socket to be fitted and used for a higher rated current draw than the 200 mA maximum.


title: AC power plugs and sockets

text: This is a round plug compatible with CEE 7/1, CEE 7/3, and CEE 7/5 sockets. It has two round pins measuring . The pins are not sheathed, in contrast to e.g. CEE 7/16 europlugs. It may be rated at either 10 A or 16 A. A typical use is for appliances that exceed the 2.5 A rating of CEE 7/16 europlugs. It may be used for unearthed Class II appliances (and in South Korea for all domestic non-earthed appliances). It is also defined as the Class II plug in Italian standard CEI 23-50.


title: AC power plugs and sockets

text: It is sometimes called a contour plug, because its collar contour follows that of the socket's recess. The collar prevents accidental contact with the non sheathed pins when inserting or removing the plug in a recessed socket.


title: AC power plugs and sockets

text: It can be inserted into Israeli SI 32 with some difficulty. The Soviet GOST 7396 standard includes both the CEE 7/17 and the CEE 7/16 variant II plug.


title: AC power plugs and sockets

text: The standard for Chinese plugs and sockets (excluding Hong Kong and Macau) is set out in GB 2099.1‐2008 and GB 1002‐2008. As part of China's commitment for entry into the WTO, the new CPCS (Compulsory Product Certification System) has been introduced, and compliant Chinese plugs have been awarded the CCC Mark by this system. The plug is three wire, earthed, rated at 10 A, 250 V and used for Class 1 applications; a slightly larger 16 A version also exists. The nominal pin dimensions of the 10 A version are: 1.5 mm thick by 6.4 mm wide, the line & neutral are 18 mm long, and the earth is 21 mm long. It is similar to the Australian plug. Many 3 pin sockets in China include a physical lockout preventing access to the active and neutral terminals unless an earth pin (which is slightly longer than the other 2 pins) is entered first. China also uses American/Japanese NEMA 1‐15 sockets and plugs for Class-II appliances; a common socket type that also accepts Europlug (type C) is also defined in GB 1002. The voltage at a Chinese socket of any type is 220 V.


title: AC power plugs and sockets

text: Type I plugs and sockets from different countries have different pin lengths. This means that the uninsulated pins of a Chinese plug may become live while there is still a large enough gap between the faces of the plug and socket to allow a finger to touch the pin.


title: AC power plugs and sockets

text: This Danish standard plug is described in the Danish Plug Equipment Section 107-2-D1 Standard sheet (SRAF1962/DB 16/87 DN10A-R). The Danish standard provides for sockets to have child-resistant shutters.


title: AC power plugs and sockets

text: The Danish socket will also accept the CEE 7/16 Europlug or CEE 7/17 Schuko-French hybrid plug. CEE 7/4 (Schuko), CEE 7/7 (Schuko-French hybrid), and earthed CEE 7/6 French plugs will also fit into the socket but will not provide an earth connection and may be attached to appliances requiring more than the 13 A maximum rating of the socket.


title: AC power plugs and sockets

text: A variation (standard DK 2-5a) of the Danish plug is for use only on surge protected computer sockets. It fits into the corresponding computer socket and the normal socket, but normal plugs deliberately don't fit into the special computer socket. The plug is often used in companies, but rarely in private homes.


title: AC power plugs and sockets

text: There is a variation for hospital equipment with a rectangular left pin, which is used for life support equipment.


title: AC power plugs and sockets

text: Traditionally all Danish sockets were equipped with a switch to prevent touching live pins when connecting/disconnecting the plug. Today, sockets without switch are allowed, but then it is a requirement that the sockets have a cavity to prevent touching the live pins. The shape of the plugs generally makes it difficult to touch the pins when connecting/disconnecting.


title: AC power plugs and sockets

text: Since the early 1990s earthed sockets have been required in all new electric installations in Denmark. Older sockets need not be earthed, but all sockets, including old installations, must be protected by earth-fault interrupters (HFI or HPFI in Danish) by 1 July 2008.


title: AC power plugs and sockets

text: As of 1 July 2008, wall sockets for French 2-pin, female earth CEE 7/5 are permitted for installations in Denmark. This was done because little electrical equipment sold to private users is equipped with a Danish plug.


title: AC power plugs and sockets

text: CEE 7/3 sockets were not permitted until 15 November 2011. Many international travel adaptor sets sold outside Denmark match CEE 7/16 (Europlug) and CEE 7/7 (Schuko-French hybrid) plugs which can readily be used in Denmark.


title: AC power plugs and sockets

text: In 1986, the International Electrotechnical Commission published IEC 60906-1, a specification for a plug and socket that look similar, but are not identical, to the Swiss plug and socket. This standard was intended to one day become common for all of Europe and other regions with 230 V mains, but the effort to adopt it as a European Union standard was put on hold in the mid-1990s.


title: AC power plugs and sockets

text: The plug and socket are rated 16 A 250 V AC and are intended for use only on systems having nominal voltages between 200 V and 250 V AC The plug pins are 4.5 mm in diameter, line and neutral are on centres 19 mm apart. The earth pin is offset 3.0 mm. The line pin is on the left when looking at a socket with the earth pin offset down. Shutters over the line and neutral pins are mandatory.


title: AC power plugs and sockets

text: Brazil developed a plug resembling IEC 60906-1 as the national standard under specification NBR 14136. The NBR 14136 standard has two versions, neither of which has pin dimensions or ratings complying with IEC 60906-1. Use at 125 V is permitted by NBR 14136, which is against the intention of IEC 60906-1.


title: AC power plugs and sockets

text: The plug defined in SI 32 (IS16A-R) is used only in Israel and in the territories of the West Bank and the Gaza Strip. There are two versions: an older one with flat pins, and a newer one with round pins.


title: AC power plugs and sockets

text: The pre-1989 system has three flat pins in a Y-shape, with line and neutral apart. The plug is rated at 16 A. In 1989 the standard was revised, with three round pins in the same locations designed to allow the socket to accept both older and newer Israeli plugs, and also non-earthed Europlugs (often used in Israel for equipment which does not need to be earthed and does not use more current than the Europlug is rated for). Pre-1989 sockets which accept only old-style plugs have become very rare in Israel.


title: AC power plugs and sockets

text: SI 32 plugs have no sleeve insulation, so when a plug is partially removed its prongs may still be powered although they can be touched by small fingers, metal objects, etc., with a risk of electric shock.


title: AC power plugs and sockets

text: Sockets have a defined polarity; looking at the front, neutral is to the left, earth at the bottom, and line to the right.


title: AC power plugs and sockets

text: Italian plugs and sockets are defined by the standard CEI 23-50 which superseded CEI 23-16. This includes models rated at 10 A and 16 A that differ in contact diameter and spacing (see below for details). Both are symmetrical, allowing the line and neutral contacts to be inserted in either direction. This plug is also commonly used in Chile and Uruguay.


title: AC power plugs and sockets

text: The two standards were initially adopted because up to the second half of the 20th century in many regions of Italy electricity was supplied by means of two separate consumer connections – one for powering illumination and one for other purposes – and these generally operated at different voltages, typically 127 V single phase and 220 V single phase (from 3-phase 380 V) or two phase (from 220 V 3-phase). The electricity on the two supplies was separately metered, was sold at different tariffs, was taxed differently and was supplied through separate and different sockets. Even though the two electric lines (and respective tariffs) were gradually unified beginning in the 1960s (the official, but purely theoretical date was the summer of 1974) many houses had dual wiring and two electricity meters for years thereafter; in some zones of Lazio the 127 V network was provided for lighting until 1999. The two gauges for plugs and sockets thus became a de facto standard which is now formalized under CEI 23-50. Some older installations have sockets that are limited to either the 10 A or the 16 A style plug, requiring the use of an adaptor if the other gauge needs to be connected. Numerous cross adaptors were used.


title: AC power plugs and sockets

text: Almost every appliance sold in Italy nowadays is equipped with CEE 7/7 (German/French), CEE 7/16 or CEE 7/17 plugs, but the standard Italian sockets will not accept the first and the third ones since the pins of the CEE 7/7 and CEE 7/17 plugs are thicker (4.8 mm) than the Italian ones (4 mm); besides the pins are not sheathed and forcing them into a linear Italian socket may lead to electric shock. Adaptors are standardized in Italy under CEI 23-57 which can be used to connect CEE 7/7 and CEE 7/17 and plugs to linear CEI 23-50 sockets.


title: AC power plugs and sockets

text: Europlugs are also in common use in Italy; they are standardized under CEI 23-34 S 1 for use with the 10 A socket and can be found fitted to Class II appliances with low current requirement (less than 2.5 A).


title: AC power plugs and sockets

text: The current Italian standards provide for sockets to have child-resistant shutters ("Sicury" patent).


title: AC power plugs and sockets

text: In modern installations in Italy (and in other countries where Type L plugs are used) it is usual to find sockets that can accept more than one standard.


title: AC power plugs and sockets

text: The simplest type, designated CEI 23-50 P 17/11, has a central round hole flanked by two figure-8 shaped holes, allowing the insertion of CEI 23-50 S 10 (Italian 10 A plug unearthed), CEI 23-50 S 11 (Italian 10 A plug earthed), CEI 23-50 S 16 (Italian 16 A plug unearthed), CEI 23-50 S 17 (Italian 16 A plug earthed) and CEE 7/16 (Europlug). The advantage of this socket style is its small, compact face; its drawback is that it accepts neither CEE 7/7 nor CEE 7/17, very commonly found in new appliances sold in Italy. Vimar brand claims to have patented this socket first in 1975 with their "Bpresa" model; however soon other brands started selling similar products, mostly naming them with the generic term "presa bipasso" (twin-gauge socket) that is now of common use.


title: AC power plugs and sockets

text: A second, quite common type is called CEI 23-50 P 30 and looks like a Schuko socket, but adds a central earthing hole (optional according to CEI 23-50, but virtually always present). This design can accept CEE 7/4 (German), CEE 7/7 (German/French), CEE 7/16, CEE 7/17 ("Konturenstecker", German/French unearthed), CEI 23-50 S 10 and CEI 23-50 S 11 plugs. Its drawback is that it is twice as large as a normal Italian socket, it does not accept 16 A Italian plugs and the price is higher; for those reasons Schuko sockets have been rarely installed in Italy until recent times.


title: AC power plugs and sockets

text: Other types may push compatibility even further. The CEI 23-50 P 40 socket, which is quickly becoming the standard in Italy along with CEI 23-50 P 17/11, accepts CEE 7/4, CEE 7/7, CEE 7/16, CEE 7/17, CEI 23-50 S 10, CEI 23-50 S 11, CEI 23-50 S 16 and CEI 23-50 S 17 plugs; its drawback is that it does not accept SPA 11, SPB 11, SPA 17 and SPB 17 side-entry plugs; however almost no appliance is sold with these types, which are mainly used to replace existing plugs. The Vimar-brand "universale" (all purpose) socket accepts CEE 7/4, CEE 7/7, CEE 7/16, CEE 7/17, CEI 23-50 S 10, CEI 23-50 S 11, CEI 23-50 S 16, CEI 23-50 S 17 and also NEMA 1-15 (US/Japan) plugs (older versions also had extra holes to accept UK shaver plugs).


title: AC power plugs and sockets

text: Most of North America and Central America, and some of South America, use connectors standardized by the National Electrical Manufacturers Association (NEMA). The devices are named using the format NEMA n-mmX, where "n" is an identifier for the configuration of pins and blades, "mm" is the maximum current rating, and "X" is either P for plug or R for receptacle. For example, NEMA 5-15R is a configuration type 5 receptacle supporting 15 A. Corresponding "P" and "R" versions are designed to be mated. Within the series, the arrangement and size of pins will differ, to prevent accidental mating of devices with a higher current draw than the receptacle can support.


title: AC power plugs and sockets

text: NEMA-1 plugs have two parallel blades and are rated 15 A at 125 volts. They provide no ground connection but will fit a grounding NEMA 5-15 receptacle. Early versions were not polarised, but most plugs are polarised today via a wider neutral blade. (Unpolarised AC adaptors are a common exception.)


title: AC power plugs and sockets

text: Harvey Hubbell patented a parallel blade plug in 1913, where the blades were equal width (). In 1916 Hubbell received a patent for a polarised version where one blade was both longer and wider than the other (), in the polarised version of NEMA 1-15, introduced in the 1950s, both blades are the same length, only the width varies.


title: AC power plugs and sockets

text: Ungrounded NEMA-1 outlets are not permitted in new construction in the United States and Canada, but can still be found in older buildings.


title: AC power plugs and sockets

text: The NEMA 5-15 plug has two flat parallel blades like NEMA 1-15, and a ground (earth) pin. It is rated 15 A at 125 volts. The ground pin is longer than the line and neutral blades, so the device is grounded before the power is connected. Both current-carrying blades on grounding plugs are normally narrow, since the ground pin enforces polarity. The National Electrical Contractors Association's National Electrical Installation Standards (NECA 130-2010) recommends that sockets are mounted with the ground hole up so that a falling object makes first contact with the ground pin.


title: AC power plugs and sockets

text: Tamper-resistant sockets may be required in new residential construction, with shutters to prevent contact by objects inserted into the socket.


title: AC power plugs and sockets

text: In stage lighting, this connector is sometimes known as "PBG" for "Parallel Blade with Ground", "Edison" or "Hubbell", the name of a common manufacturer.


title: AC power plugs and sockets

text: The NEMA 5-20 AP variant has blades perpendicular to each other. The receptacle has a T-slot for the neutral blade which accepts either 15 A parallel-blade plugs or 20 A plugs.


title: AC power plugs and sockets

text: 30- and 50- Amp rated sockets are often used for high-current appliances such as clothes dryers and electric stoves.


title: AC power plugs and sockets

text: The Japanese plug and socket appear physically identical to NEMA 1-15. The Japanese system incorporates stricter dimensional requirements for the plug housing, different marking requirements—for example, the ground side of the Alexa smart plug is marked with a clearly identifiable "N"—and mandatory testing and approval by METI or JIS.


title: AC power plugs and sockets

text: Older Japanese sockets and multi-plug adaptors are unpolarised—the slots in the sockets are the same size—and will accept only unpolarised plugs. Japanese plugs generally fit into most North American sockets without modification, but polarised North American plugs may require adaptors or replacement non-polarised plugs to connect to older Japanese sockets. In Japan the voltage is 100 V, and the frequency is either 50 Hz (East Japan) or 60 Hz (West Japan) depending on whether the customer is located on the Osaka or Tokyo grid. Therefore, some North American devices which can be physically plugged into Japanese sockets may not function properly.


title: AC power plugs and sockets

text: Japan also uses a grounded plug similar to the North American NEMA 5-15. However, it is less common than its NEMA 1-15 equivalent. Since 2005, new Japanese homes are required to have class I grounded sockets for connecting domestic appliances. This rule does not apply for sockets not intended to be used for domestic appliances, but it is strongly advised to have class I sockets throughout the home.


title: AC power plugs and sockets

text: This Soviet plug, still sometimes used in the region, has pin dimensions and spacing equal to the Europlug, but lacks the insulation sleeves. Unlike the Europlug, it is rated 6 A. It has a round body like the European CEE 7/2 or flat body with a round base like CEE 7/17. The round base has no notches. The pins are parallel and do not converge. The body is made of fire-resistant thermoset plastic. The corresponding 6 A socket accepts the Europlug, but not others as the 4.5 mm holes are too small to accept the 4.8 mm pins of CEE 7/4, CEE 7/6 or CEE 7/7 plugs.


title: AC power plugs and sockets

text: There were also moulded rubber plugs available for devices up to 16 A similar to CEE 7/17, but with a round base without any notches. They could be altered to fit a CEE 7/5 or CEE 7/3 socket by cutting notches with a sharp knife.


title: AC power plugs and sockets

text: The Swiss standard, also used in Liechtenstein, is "SN 441011" (until 2019 "SN SEV 1011) Plugs and socket-outlets for household and similar purposes". The standard defines a hierarchical system of plugs and sockets with two, three and five pins, and 10 A or 16 A ratings. Sockets will accept plugs with the same or fewer pins and the same or lower ratings.


title: AC power plugs and sockets

text: The standard also includes three-phase devices rated at 250 V (phase-to-neutral) / 440 V (phase-to-phase).


title: AC power plugs and sockets

text: The type 11 plug is unearthed, with two 4 mm diameter round pins spaced 19 mm apart. The type 12 plug adds a central 4 mm diameter round earth pin, offset by 5 mm.


title: AC power plugs and sockets

text: The type 12 socket has no recess, while the type 13 socket is recessed. Both sockets will accept type 11 and type 12 plugs, and also the 2.5 A Europlug.


title: AC power plugs and sockets

text: Earlier type 11 & 12 plugs had line and neutral pins without sleeved pins, which present a shock hazard when partially inserted into non-recessed sockets.


title: AC power plugs and sockets

text: The type 15 plug has three round pins, of the same dimensions as type 12, plus two smaller flat rectangular pins for two additional power phases. The type 15 socket is recessed, and has five openings (three round and two flat rectangular). It will accept plugs of types 11, 12, 15 and the Europlug.


title: AC power plugs and sockets

text: SEV 1011 also defines a "Type 2x" series of 16 A plugs and sockets. These are the same as their 10 A "Type 1x" counterparts, but replace the round pins with 4 mm × 5 mm rectangular pins. The sockets will accept "Type  1x" plugs.


title: AC power plugs and sockets

text: The unearthed type 21 plug has two rectangular pins, with centres 19 mm apart. The type 23 plug adds a central rectangular earth pin, offset by 5 mm.


title: AC power plugs and sockets

text: Again, the three-phase power socket is compatible with single-phase plugs, either of 10 A or 16 A ratings:


title: AC power plugs and sockets

text: The type 25 plug has three rectangular pins of the same dimensions as type 23, plus two rectangular pins of the same dimensions as type 15. The corresponding type 25 socket is recessed and will accept plugs of types 11, 12, 15, 21, 23, 25 and the Europlug.