Voltage Drop
K-factor method: VD = 2·K·I·L ÷ CM (single phase) or 1.732·K·I·L ÷ CM (three phase). K = 12.9 Cu, 21.2 Al. CM per Chapter 9 Table 8.
NEC informational notes (210.19(A) IN 4, 215.2(A) IN 2) suggest ≤3% on a branch circuit or feeder and ≤5% overall. These are recommendations, not requirements, except where another rule (e.g., 647, 695, or the AHJ) applies. Upsizing for voltage drop requires the EGC to be upsized proportionally (250.122(B)).
Reference only — not engineering, legal, or code-compliance advice. Results are estimates for qualified persons and must be verified against the NEC edition adopted where the work is done (your selected edition), manufacturer instructions, and the local AHJ. Use is subject to the Terms of Use & Disclaimer. — Morningstar Electric LLC