110V vs 220V

This thread seems to bounce between topics or aspects of the original question. If a device needs 20A or less at 120V to operate, there is no advantage of changing it to 220V operation. This gets debated on other forums I visit, for woodworking, and there are other opinions. But there is no data to support those opinions. The motor basically doesn't care which voltage it gets (assuming it can handle both). Current has to be almost exactly twice as high at 120V so there could be a inconsequential I squarred R difference but it won't be significant to operation. If you just like the idea of 220V and the device is available at that level and you have an outlet, there is no harm to getting it that way.

If a device needs more than 20A at 120V, it has to run on 220V. There are no higher current 120V breakers and outlets, at least that I've ever seen. If they are available they will be too expensive to be practical. Some houses may not have 20A circuits but most should. You can't simply change the breaker, 15A circuits use 14 gauge wiring, 20A circuits use 12 gauge. If you put a 20A breaker on 14 gauge wiring and use more than 15amps the wiring will be higher in temperature than it is designed to be and the insulation may fail. It isn't safe. 220V circuits can be as much as 50A or more so they can handle a lot more power. 220V at 20A is twice the power as 120 at 20A.

You don't want to buy a device meant for use in Europe and use it in the U. S. (or vice versa). US power is 60 Hz and Europe is 50 Hz. Any synchronous motor will not run properly and may not run at all just due to the frequency difference. European 230V power is single phase, line to ground, like US 120V. US 220V power is line to line power - two hots, typically black and red, not line to ground. So the voltage is more different than it might appear.
 
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... If a device needs more than 20A at 120V, it has to run on 220V. There are no higher current 120V breakers and outlets, at least that I've ever seen. If they are available they will be too expensive to be practical. ....

30amp, 110/120v is commonly used for RV hookups, and sometimes 50amp 110/120v. Cost of breakers and outlets is about the same as 220/240v versions.

15amps, 110/120v is most common in homes. 20amp, 110/120v is also fairly common. 220/240v is more practical for higher power applications.

I agree that if you want more than 20amps (or even 15amps), better to go 220/240v.