Conductors
Voltage Drop & Wire Size
Voltage drop is a performance rule, not a safety rule — ampacity and overcurrent protection still govern. This calculator finds the smallest conductor that holds your drop target, then warns you if that conductor cannot legally carry the current.
What it asks for
- Circuit
- Circuit voltage (V)
- Current (A)
- One-way run length (ft)
- Max allowable drop (%) — PV source & battery circuits: 2%. Feeders: 3%.
- Conductor
Uses DC resistance from NEC Chapter 9, Table 8, uncoated conductors. Does not include AC reactance — for long large AC feeders use Table 9.