What Size Wire for a 70 Amp Circuit Breaker? (NEC Table 310.16)
Complete Copper vs. Aluminum AWG wire size, continuous load limit (56A max), ground wire gauge, and conduit sizing for 70A circuits (Subpanels, large heat-pump air handlers & commercial feeders).
Direct NEC Table 310.16 Answer for 70 Amps
Common Applications for a 70A Circuit
Subpanels, large heat-pump air handlers & commercial feeders. Remember that under the NEC 125% continuous-load rule (NEC 210.19 & 210.20), a standard 70A breaker can only supply up to 56A of continuous load (any load that runs for 3 hours or more without stopping, such as an EV charger or commercial lighting).
When to Upsize for Voltage Drop (Over 100 Feet)
If your one-way wire run exceeds 100 feet at 240V (or 50 feet at 120V), step up one wire gauge from 4 AWG to keep total line voltage drop under the NEC 3% branch-circuit recommendation. Use our Voltage Drop Calculator to check your exact footage.