P = power in watts

I = current in amps

E = voltage in volts

P=IE use your math to get any value knowing 2 of the three values.

I use a book called "an introduction to electrical wiring" by John M. Doyle as a reference for wiring information.

JMHO

Carl

For single phase divide your watts by the voltage to get amps. You'll find on your residential system that the 220 volt heater will draw 1/2 the amps that the 110 volt heater will at the same watts. Depending on the total watts used the 220 volt unit will allow you to go a size smaller on the circuit conductors.

If your concerned about voltage drop for a residential circuit, don't be unless it is an exceptionally long run. If you are concerned then consult any electrical formula book or put "voltage drop" in a google search engine. Hope this helps.

Ron