<story><title>Why does the USA use 110V and UK use 230-240V? (2014)</title><url>https://electronics.stackexchange.com/questions/115200/why-does-the-usa-use-110v-and-uk-use-230-240v</url></story><parent_chain><item><author>Kirby64</author><text>How many residential appliances benefit from three phase, and is the benefit outweighed by the additional cost of more copper for the additional wires?&lt;p&gt;For example, a common big motor that needs a starter capacitor is a HVAC unit. Usually the copper to run those is extremely expensive, on the order of hundreds of dollars. Adding an additional wire may add an additional hundred dollars or more. By comparison, starter caps are quite cheap. $20 for a HVAC sized one. That also isn&amp;#x27;t counting any of the costs of three phase infrastructure for breakers etc.&lt;p&gt;That also isn&amp;#x27;t even counting that many appliances are moving to inverter based technologies that don&amp;#x27;t utilize induction motors at all, such as induction hobs. Or, many appliances with no benefit from extra phases (resistive heating devices such as ovens, dryers, toasters, etc).&lt;p&gt;Seems to me that the tradeoff is worth it.</text></item><item><author>jhoechtl</author><text>&amp;gt; Really all residential connections in the US are 220V split phase&lt;p&gt;Really all modern residential connections in Europe are 400V  three phase electric power, capable to immediately power an electric motor without the need of capacitors.&lt;p&gt;No matter how you put it, the US residential power grid is conceptionally lagging.</text></item><item><author>somat</author><text>Really all residential connections in the US are 220V split phase. The nice thing about  split phase is that it is easy to well... split and run two linked 110V circuits, so most houses will have a few 220V items(ovens, airconditioner) and the rest wired half with phase A the other half with phase B. all of our consumer items expect this 110V&lt;p&gt;As to why split phase.... I am not really sure. Really, I wish a three phase residential had become normal instead. All the advantages of split phase but now your motors don&amp;#x27;t have to suck. I have heard a three phase residential connection is common in some parts of Germany, lucky bastards.&lt;p&gt;One interesting side note is how the US last mile distribution layout is different than germany. The US uses a lot more smaller transformers, really one per street. while germany uses fewer larger transformers, one per neighborhood. not sure which one is better I bet the german layout is more efficient. but I will note it is a lot easier to keep spares and change out a small transformer.</text></item></parent_chain><comment><author>jonhohle</author><text>Others have made the comment about lower current requirements at high voltage, but from a maintenance perspective, that $20 capacitor is a common failure part. Calling an HVAC repair company to diagnosis, parts, and labor it costs around $200 for anyone not electrically minded. Over the life of an AC unit, starter&amp;#x2F;run caps might have to replaced twice.&lt;p&gt;Even if an extra conductor in the line was a few hundred dollars, I’d rather have one less common failure point. In AZ AC is effectively required in the summer. AC outages are similar to winter furnace outages in northern areas. I have extra caps ready to deploy (we lose a cap about every 3 years across multiple units) but have never needed to unexpectedly replace copper.</text></comment>
<story><title>Why does the USA use 110V and UK use 230-240V? (2014)</title><url>https://electronics.stackexchange.com/questions/115200/why-does-the-usa-use-110v-and-uk-use-230-240v</url></story><parent_chain><item><author>Kirby64</author><text>How many residential appliances benefit from three phase, and is the benefit outweighed by the additional cost of more copper for the additional wires?&lt;p&gt;For example, a common big motor that needs a starter capacitor is a HVAC unit. Usually the copper to run those is extremely expensive, on the order of hundreds of dollars. Adding an additional wire may add an additional hundred dollars or more. By comparison, starter caps are quite cheap. $20 for a HVAC sized one. That also isn&amp;#x27;t counting any of the costs of three phase infrastructure for breakers etc.&lt;p&gt;That also isn&amp;#x27;t even counting that many appliances are moving to inverter based technologies that don&amp;#x27;t utilize induction motors at all, such as induction hobs. Or, many appliances with no benefit from extra phases (resistive heating devices such as ovens, dryers, toasters, etc).&lt;p&gt;Seems to me that the tradeoff is worth it.</text></item><item><author>jhoechtl</author><text>&amp;gt; Really all residential connections in the US are 220V split phase&lt;p&gt;Really all modern residential connections in Europe are 400V  three phase electric power, capable to immediately power an electric motor without the need of capacitors.&lt;p&gt;No matter how you put it, the US residential power grid is conceptionally lagging.</text></item><item><author>somat</author><text>Really all residential connections in the US are 220V split phase. The nice thing about  split phase is that it is easy to well... split and run two linked 110V circuits, so most houses will have a few 220V items(ovens, airconditioner) and the rest wired half with phase A the other half with phase B. all of our consumer items expect this 110V&lt;p&gt;As to why split phase.... I am not really sure. Really, I wish a three phase residential had become normal instead. All the advantages of split phase but now your motors don&amp;#x27;t have to suck. I have heard a three phase residential connection is common in some parts of Germany, lucky bastards.&lt;p&gt;One interesting side note is how the US last mile distribution layout is different than germany. The US uses a lot more smaller transformers, really one per street. while germany uses fewer larger transformers, one per neighborhood. not sure which one is better I bet the german layout is more efficient. but I will note it is a lot easier to keep spares and change out a small transformer.</text></item></parent_chain><comment><author>japanuspus</author><text>I read this comment as implicitly assuming two phases to require less copper than three. In reality, the total copper cross-section needed to transfer power in a multi-phase system _decreases_ with increased number of independently wired phases (all else being equal).</text></comment>