[user2342]

> How many residential appliances benefit from three phase, and is the benefit outweighed by the additional cost of more copper for the additional wires?

Three phase wiring is so ubiquitous here, there is nearly no additional cost.

[Kirby64]

You can't just say there's no cost because you don't see it. You don't have the option, so of course there's no way to tell price differentiation. I'm talking purely of raw material cost though. By adding a 3rd load conductor, you inherently add wiring cost and complexity, which should result in cost to the consumer.

It may be offset, as others point out, by power delivered being higher (and thus, wire gauge can go down) when running 3 phase... however that will largely depend on the load.

[bluGill]

Most people have so few things in their house that would benefit from 3 phase that the cost isn't worth it. That extra wire isn't cheap, even if you downsize them all you still pay more. And as others have pointed out modern motors are (slowly) switching to using a VFD to generate 3 phase so there is even less need (in fact in industry a lot of equipment is switching to a VFD even though 3 phase is wired to the machine)

[timc3]

The cost is insignificant.

I have monitoring on all the phases on my house (in Sweden) and I can charge two electric cars, run the heating in winter, run the washer and drier and cook with two ovens a microwave and the induction hob at the same time and everything just works.

Things on three phase in my home: swimming pool, sauna, induction hob, electric car chargers, heating system and I have sockets to plug-in welding and other power hungry equipment. The rest is split on the phases. I can’t remember whether my solar system supplies on three phases or not but I think it does.

[briHass]

Yeah, but how many amps? What really matters is what your total available wattage is. In the US, 240v@200A (48KVA) is not uncommon. My 1979 house and every other one on the block has that, and that was assuming fossile fuel heat.

That can easily support all the things you listed and do it for a 2500 sq ft house, based on the overly conservative and outdated US NEC lead calculations.

[timc3]

Sure it’s 3 phases of 32 Amps. I can request more, but it’s not required.

[bluGill]

You have it so they use it, but single phase will run it all just fine. The pool pump and welder can benefit from 3 phase, but for the pool pump the benefit is marginal. For the welder a modern inverter welder is better yet.

[timc3]

We can get 400v 3phase inverter welders here.

Yes, we have it so we use it - for sure.

The pool pump on 3 phases seems slightly more efficient when I compared them last time. The pool is also being fitted with a heat pump inverter, which doesn’t need 3 phase.