What is the voltage drop per 100 ft?

Voltage drop per 100 feet depends on wire size and current, not just distance. The anchor numbers at 120V: 12 gauge carrying 15 amps loses about 4.8 volts over 100 feet, right at 4 percent. Fourteen gauge at the same load loses over 6.

Ten gauge at 15 amps drops about 3 volts per 100 feet; at its full 30 amps, roughly 6.

Two levers cut any of these in half: one wire size up, or doubling the voltage, since 240V halves the percentage for the same volts lost.

Remember the round trip; 100 feet of run is 200 feet of conductor, which the per-foot resistance tables already assume when stated as drop per run length.

The voltage drop per length calculator gives your exact wire, load, and distance without the interpolation.