Derating | Wire

You are running eight 12 AWG THHN wires through a single conduit to power different circuits.

This is not linear. Doubling the current the heat. A wire carrying 20A generates four times the heat of one carrying 10A. derating wire

Wire is sold with a standard ampacity rating (e.g., 12 AWG copper is rated for 20 amps). However, this rating assumes ideal conditions: a single wire, in open air, at a specific ambient temperature (usually 86°F / 30°C). You are running eight 12 AWG THHN wires

32.16A < 56.25A → FAIL. Solution: Increase to 4 AWG (base 95A) and recalculate. in open air

When you derate correctly, you don’t just follow code—you guarantee that the insulation remains intact, the breaker stays closed, and the building stays standing.