Comment by nine_k
12 hours ago
Rewiring an entire country is a wee bit expensive. Even if the wires are rated to 300V (they usually are), transformers would have to be replaced, and they cost quite a bit. Also different sockets and circuit breakers, and a whole lot of billable hours by licensed electricians.
(But changing the voltage is easy compared to changing the mains frequency. Japan still has to live with 50Hz in one half of the country, and 60Hz in the other.)
The transformers are fine as they are. We already have 240VAC in the typical US home: Two legs of 120v, with one being 180° out of phase. That part exists and it works fine -- the big industrious parts of the infrastructure are already supplying 240v.
US 240v is a bit different than the way the rest of the world usually does it, where they have 1 leg of 240v and 1 neutral, but AFAICT that detail is not a big deal for the stuff that actually uses electricity.
The wire itself, broadly-speaking, is fine.
Suppose we decided that tomorrow at noon to begin the move to 240v.
We just refactor our breaker panels and update to some new objectively-good whiz-bang outlet format (because we would certainly never borrow existing designs from anywhere else on the planet; we in the States have a big problem with Not Invented Here when it comes to policy), and finally get rid of twist-in Edison light bulb sockets, and that part is done.
But then all kinds of stuff doesn't work anymore.
Fridges, garage door openers, microwaves, light bulbs, clock radios, natural gas furnaces, and anything else that doesn't work with 240v: That stuff is dead in the water without converting back down to 120v using an autoformer or something.
Sure, we'll eventually get things updated; when we don't count survivorship bias examples, it's plain to see that stuff just doesn't last all that long anyway (and never actually did).
But for a time: There literal mountains of stuff that just won't work without help. And that's a tough pill to swallow.
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What we could start doing is embrace our existing dual-voltage home wiring methods, and putting 240v sockets in some places where it's actually beneficial. Places like kitchens (for heating water and food), say. But broadly speaking: Nobody does this because nobody sells safety-approved residential appliances for the US domestic market, so it's a lot of money to spend to get it done for no benefit. It's a catch-22.