Why does the USA use 110V and UK use 230-240V?

Re:Why does the USA use 110V and UK use 230-240V? by LeifCarrotson on Tuesday August 29, 2023 @01:27PM (#37311107)

> Unless it is a very old construction or a smaller home, houses in the US as well as most of americas are provided with multiple phases in Y configuration (3-phase, 4 wires, one neutral).

> So, for a small apartment, maybe you'll get a single phase wire plus the neutral, or more commonly 2-phase wires plus neutral, up to the full 3 phase wires plus neutral.

> The phases are usually 220V between then and 120 between any individual phase and the neutral connector.

I am an American - an electrical engineer in the Midwest - and I was on roofs last week after a tornado came through our town, working with the distribution panels. What you said is not correct. Homes get 240/120 nominal line voltage, or 220/110V at the load, 180 degrees out of phase, plus a neutral.

That is not the same as two phases plus the center conductor of 3-phase Y.

In industrial facilities, it's reasonably common 208V 3-phase in a Y configuration, with three wires each 120 degrees out of phase with each other. This is typically used for lighting circuits, because it's 120 phase to ground and can use commodity bulbs and ballasts. More commonly, machines will run off 480V 3-phase, which is 277 phase-to-ground.

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Re:Why does the USA use 110V and UK use 230-240V? by elzbardico on Tuesday August 29, 2023 @01:32PM (#37311177)

I stand corrected and added a disclaimer in my original comment. Thanks for teaching me something I assumed incorrectly.

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Re:Why does the USA use 110V and UK use 230-240V? by coding123 on Tuesday August 29, 2023 @02:08PM (#37311647)

Just for knowledge sake: you are correct that there are 4 wires:

    1 - hot 1 120 v
    2 - hot 2 120 v
    3 - neutral
    4 - ground

The hot 1 and 2 are 180 degrees out of phase with each other which is why 240v appliances can consider having those 2 wires (and at least the neutral) to be a 240v appliance.

And to be more pedantic about it, the ground is not provided not by the power company but the ground. I have 3 lines coming from the grid to my pole, line 1, 2 and the neutral that is created by the transformer. The ground comes from my ground - a long copper wire that goes a few feet down and back up. All ground connections in the (future) house will go there. Ground is also bonded with neutral at the box on my pole.

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Re:Why does the USA use 110V and UK use 230-240V? by MichaelZuo on Tuesday August 29, 2023 @01:34PM (#37311203)

Same in Canada, though with 600V 3-phase instead of 480V, mostly.

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