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Most domestic power in the developed world is supplied at 230V (±10V).

I presume it's a "sweet spot" for something, perhaps:

  • the highest voltage that won't jump certain insulators
  • a balance of voltage vs lethal danger
  • the highest voltage that won't fry various components

Why has that voltage been chosen just about everywhere?

Bohemian
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  • Historical (think about when the first systems were being installed - who was doing it?). However, there are plenty of places that don't. – JIm Dearden Jan 06 '17 at 20:22
  • For the sake of silly correctness, the statement that "most domestic power around the world is supplied with 230V" is plain wrong. The domestic AC in North America is 110V. To illustrate this further, here's a [map of mains voltages around the globe](https://en.wikipedia.org/wiki/Utility_frequency#/media/File:Worldwide_map_of_voltage_and_frequency.png). – Nick Alexeev Jan 06 '17 at 20:25
  • Also relevant: http://electronics.stackexchange.com/questions/115200/why-does-the-usa-use-110v-and-uk-use-230-240v – dim Jan 06 '17 at 20:26
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    @Nick My understanding is that power in the USA is supplied to *the house* at 220V, for directly powering permantently installed appliances (ovens etc), but stepped down for power outlets for safety – Bohemian Jan 06 '17 at 20:26
  • @NickAlexeev still, at least judging by square miles, 220 leads :) –  Jan 06 '17 at 20:30
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    @Boh: Power in the US is supplied to homes at 240 V center tapped, with the center tap grounded. That means two 120 V ends. Most circuits are between one of the ends and the center, so 120 V. High power appliances are across both ends, so 240 V. – Olin Lathrop Jan 06 '17 at 21:07
  • 230V is the result of nice round metric 100V, being doubled for usefulness in Europlaces, and then being given several 5% "bumps" in order to increase system capacity without shortening light-bulb life too noticeably much. The bumps were spaced 5-20 years apart to give light bulb makers time to update their product for the next bump. Most of this happened when incandescent light was the #1 load. Now indeed EU has settled at 230, UK at 240 winding back to 230 for harmonisation, and US at 240. "110/220" is colloquial probably because the bumps were there when it was first mass marketed. – Harper - Reinstate Monica Jan 06 '17 at 21:11
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    @NickAlexeev From that map I'd estimate >6 out of 7 billion (probably 90%) people use 220/230/240V so I think Bohemian has some leeway in saying "Most domestic power [is] 230V" – Sam Jan 06 '17 at 22:24

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The voltage standard is a compromise between the following requirements:

  • We want to keep the wire small.
  • We want to keep the I2R transmission losses small.
  • Safety so we do indeed need somewhat low voltage.

The frequency standard is a compromise between

  • Transmission line losses which mean we want lower frequency.
  • And transformer size.

Electrical components are designed to endure a certain voltage/current. So a designer will never design something that has a maximum of 50 V if the main power supply is 230 V. A good manufacturer will design a system that can operate under both 230 V and 110 V. To do so, you will need a very good regulator for the device.

Dave Tweed
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12Lappie
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  • Until switched mode power supplies became common the input voltage range for devices was typically 20% to 5% of the rated supply depending on the fussiness of the apparatus. Voltage selector switches or taps were provided to move from one range to the next for this reason. Having a range of 110 to 240V in a recent sophistication of wide input range switch mode supplies. During the interim years there were manually or automatically range switched inputs that would support 110-120V AND 220-250V but values in between would cause faulty operation of hazard. – KalleMP Jan 07 '17 at 15:41
  • The higher voltage limit was also a consequence of the need for switch contact gaps and wire and equipment insulation to prevent arcing or insulation breakdown. – KalleMP Jan 07 '17 at 15:44