NEC Voltage Drop Calculator
Calculate voltage drop on a feeder or branch using NEC Chapter 9 Table 9 conductor resistance. Compares the result against NEC informational guidance — 3% on a branch, 5% combined feeder + branch.
Voltage drop
3.82 V
Percent drop
0.80%
✓ Within NEC informational guidance — < 3% (branch circuit).
Based on NEC Chapter 9, Table 9 AC resistance for uncoated copper in steel conduit at 75°C (aluminum approximated as 1.6× copper). For exact AC resistance with reactance correction, consult NEC Table 9 for the specific raceway type and conductor coating.
Need cable sizing for a generator install?
Our team sizes feeders, transfer-switch terminations, and grounding to NEC and AHJ requirements as part of every install.