> How many residential appliances benefit from three phase
Induction hobs, saunas, EV chargers, to name some.
> and is the benefit outweighed by the additional cost of more copper for the additional wires?
Additional cost? You don't run that many 3-phase circuits, so the cost is negligible, and your 110V circuits require substantially higher current than ours (meaning thicker wires) so if anything I'd guess the cost for wiring a US home is on average higher than a European home.
To fair comparison, it's 3 phase 400V vs single phase 200V. I agree Europe system is better but it's not worth to change with huge costs.
Modern heat pumps in Japan with inverter is just fine with 100V or 200V for home, even for cheaper coolers. 200V hear pump electrical water heater (with tank) too.
Most houses sign up only up to 6kW or 10kW electricity, so EV charger will become a problem for family that has multiple EVs, but they will be fine with slower charging at night in most cases.
It's pain that common 100V ovens works poorly. 100V Washer dryer works barely okay thanks to efficiency. I want more 200V home appliances, like 200V 3kW kettle!
I'm talking about appliances that benefit specifically from three phase because of the benefits of induction motor driving. Water heaters, ovens, EV chargers, and many other things specifically do not benefit from this. The only thing you get is power density by effective 400V output from 3-phase 240V.
Obviously 100V would be terrible for high power stuff. I'm not suggesting that. But, 240V split-phase is more than sufficient for the vast majority of residential appliances, including EV charging.
> Water heaters, ovens, EV chargers, and many other things specifically do not benefit from this. The only thing you get is power density by effective 400V output from 3-phase 240V.
They do too. You have lower current intensity, lower cable diameter, lower losses.
For EV charger it is even more relevant because anything inverter based has (theorically) a better efficiency in a three phases system.
The only drawback of three phase power is currently the cabling complexity. The home electrical panel need to be careful of the phases's balance.
I specifically was referencing any benefits from induction motor drive with 3 phase. Of course you get lower current when you run higher voltage and more phases. But, again, that isn't free. You're paying for extra conductors and insulation.
Regarding EVs... I would assume that depends on the design. No EV sold in north america is even capable of being charged off 3-phase AC anyways, so it would require quite the redesign.
In the house we're currently buying there's actually an old laundry spinner (?) in the cellar, hooked up to three-phase power. The electrician mentioned that those motors basically never broke down and were far more reliable than 230 V one-phase devices. However, other concerns, like being able to put the washing machine in your flat out how many such outlets you actually have, probably phased those devices out. I'm not sure I'd consider a three-phase outlet for the rewiring now. The stovetop of course gets that, and, if necessary one day, the wall box for EV charging, but there's not many appliances these days that need it.
Not sure the electricians comment is related specifically to the three-phase itself, or just to the general observation that three-phase motors are put in more industrial/commercial applications, where reliability is much more important. Pair that with residential use of commercial appliances tends to be very gentle on them (e.g., they don't get run 24/7, vs. a commercial place that would try to use them at every possible moment) and you have a recipe for a very reliable device.
I asked them whether it was specifically about that and they said yes. The appliance in question was a consumer item, just a tad older, not a repurposed industrial machine.
Induction hobs, saunas, EV chargers, to name some.
> and is the benefit outweighed by the additional cost of more copper for the additional wires?
Additional cost? You don't run that many 3-phase circuits, so the cost is negligible, and your 110V circuits require substantially higher current than ours (meaning thicker wires) so if anything I'd guess the cost for wiring a US home is on average higher than a European home.