How To Calculate Voltage Drop

Use the following formula as a guide for calculating the voltage drop of a copper conductor.

Voltage Drop = Factor x Amps x Feet / 100

Copper Conductor: 80% Power Factor
Wire Size Single Phase Three Phase
14 AWG 0.4762 0.4167
12 AWG 0.3125 0.2632
10 AWG 0.1961 0.1677
8 AWG 0.1250 0.1087
6 AWG 0.0833 0.0714
4 AWG 0.0538 0.0463
3 AWG 0.0431 0.0379
2 AWG 0.0370 0.0323
1 AWG 0.0323 0.0278
1/0 AWG 0.0269 0.0231
2/0 AWG 0.0222 0.0196
3/0 AWG 0.0190 0.0163
4/0 AWG 0.0161 0.0139
250 MCM 0.0147 0.0128
300 MCM 0.0131 0.0114
350 MCM 0.0121 0.0106
400 MCM 0.0115 0.0091
500 MCM 0.0101 0.0088

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Warning: When using this information to perform electrical work, call a licensed electrician and consult the NEC® for safety. All licensed electricians have passed examinations covering the National Electric Code®, know state and local building codes, and may carry insurance to cover damages.