Portable cord

A portable cord (also known as portable cordage, flexible cord, or extension cord) is a cable with multiple conductors used for temporary electrical power connections requiring flexibility. The cord can be employed in a range of applications, such as operating motors in small and large tools, equipment, power extensions, home appliances, and machinery.
Description.
Portable cords may be used in commercial, industrial and residential applications. Some are used on job sites where resistance to oil, chemicals, and abrasion is essential in extreme environments – both the heat and the cold, outside or inside. Additionally, some portable cords can be water-resistant or water-submersible. Portable cords are commonly used in a range of facilities, such as construction sites, mills, mines, sports complexes, or even marinas. 
Although the construction of a portable cord varies depending on the type, a standard cord has at least two stranded copper conductors sized between #18 and #2 American wire gauge (AWG). The copper stranding, insulation, and outer jacket directly influence the physical properties of the cord and its permitted uses.
Types.
A variety of portable cords, differing in styles, lengths, and thicknesses exists in the marketplace. Common types include Type SJT, SVT, SEOW, SJ, SJOW, SJOOW, SO, and SOW, each designed for specific applications.
A portable cord is usually made of thermoset polymer, thermoplastic elastomer, or thermoplastic. Thermoset cords have heavy-duty-grade rubber jackets, are extremely sturdy and oil-resistant, and may remain flexible over a temperature range of . Thermoplastic elastomer (TPE) cords have medium-duty thermoplastic elastomer jackets and perform well in cold conditions down to . Thermoplastic cords typically have an extruded plastic PVC jacket, and are intended for light-duty use, typically in a temperature range of .
Letter codes.
In the United States, letter codes have been defined by Underwriters Labs (UL) to describe various attributes and ratings of portable cords. The Canadian Standards Association (CSA) also has defined similar letter codes, and ongoing standards harmonization should eventually resolve minor differences.