{Don’t get your panties in a bunch if this explanation is not immediately understandable but} for heaters, power factor is close the 1.0, or “unity,” so only the resistive component [er, copper size] of a circuit matters. For motors, where PF<1, the reactive component of circuit impedance figures in, so conductor spacing and ferrous versus non-ferrous versus non-metallic raceway or cable jacket has an effect on voltage drop.
Offhand, I’d be tempted to save some copper by using a 240V (over 120V) heater, but looks like 240V elements start at >2kW. Then it’s a matter of what’s cheaper—a 2-pole breaker or fatter wire. If line voltage is normal, use 12AWG for 1650 watts at 100 feet. Change in performance will be barely measurable with larger cable.
[This message has been edited by Bjarney (edited 08-04-2003).]
