ZovaTool

Voltage Drop Calculator

Voltage Drop
7.72 V
% Drop
6.43 %
NEC
Exceeds NEC
Recommended
AWG 2

How to use the Voltage Drop Calculator

  1. Enter source voltage, load current and one-way wire length.
  2. Pick wire gauge (AWG) and material (copper or aluminum).
  3. Choose single- or three-phase.
  4. Read voltage drop, percent drop and NEC compliance.
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Wire sizing and voltage drop

NEC recommends ≤3% drop on branch circuits and ≤5% combined for feeder + branch.

Voltage drop = 2 × R × L × I for single-phase (× √3 for three-phase). Long runs need bigger wire.

Aluminum is ~60% as conductive as copper — upsize 2 AWG sizes when substituting.