Derating Wire Jun 2026

When current flows through a wire, it generates heat (Joule heating). If the wire cannot dissipate that heat—because it is hot outside, surrounded by insulation, or packed tightly with other wires—the insulation can melt. This leads to short circuits and fire hazards.

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. derating wire

The National Electrical Code provides Table 310.16 (ampacities) and mandates derating via: When current flows through a wire, it generates