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Comment by throwawayish | Hacker News Reader

In most parts of Europe 3-phase is the standard. Neither high-leg delta nor split phase have significant deployment outside North America.

That being said, in household use the per-household balancing between the phases is usually very poor (e.g. all lightning on one phase). Overall the balancing turns out ok across the grid, but the meter doesn't see that. So this is a very relevant condition for household meters.

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Ah. That's helpful. US utility residential practice, for those outside the US, is that pole transformers take in 3 phase at a few KV, at 60Hz, and output 120/240 VAC single phase with a shared neutral. That's what most houses get, supplied over 3 wires, with a 3-wire single phase meter. Pole-mounted transformers usually serve about 7 houses or so.

Even in apartment buildings, each apartment has its own meter, almost always single phase.

I'm interested in what area the overhead lines are only 1.1 kV. From what I have seen the high-side voltages are much higher, in the range of 7 kV or 14.4 kV line to ground.

Also, most overhead transformers I have seen are entirely single phase. Often you will see a bank of 3 single-phase transformers if a customer requires 3 phase service. Larger customers are connected to a pad-mounted 3-phase transformer connected to the primary overhead service through an underground dip from the pole.

You can't "take in 3 phase and output single phase". That's not how a transformer works. It'd be amazing if it did, as in Nobel Prize winning.

In the US most homes are just tapped to 1 phase, if there are 3 on the pole.

Yeah, you are right. I think what they were trying to say is that the transformers are fed on the high side by one of three phases (as is typical), and that the residential step-down is a split phase 120/240.

Yes, that is the normal configuration for power delivery to a residence in most of North America.

U.K. is single phase per house.

Yes - we had a power cut recently and when I went outside you could see it was affecting every third house, i.e. just a single phase had gone. Reported it and it was fixed promptly.

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