Chart - Wire Derating

The mixer draws 16 amps under full load. Well within limit.

losses). While a single wire in open air can dissipate this heat easily, wires bundled in a conduit or located in hot environments (like attics or rooftops) can reach temperatures that degrade, melt, or ignite insulation. Using a derating chart ensures code compliance—specifically with the National Electrical Code (NEC) —and prevents fire hazards. Primary Derating Factors wire derating chart

If you are running that wire through a hot attic, stuffing it into a conduit with five other wires, or exposing it to direct sunlight, that "20 amp" rating drops significantly. This is where the (often called Ampacity Correction Factors) becomes the most important tool in your kit. The mixer draws 16 amps under full load

Let’s look at how to apply the values found in standard NEC tables. Note that wire insulation types matter. Most modern wiring is THHN/THWN-2. While a single wire in open air can

For example, if you need to run a 20A circuit in an environment with an ambient temperature of 50°C (122°F) using a 3-conductor cable, you would:

That’s the new maximum before insulation damage. But the breaker is 20A, so the circuit is limited to 20A anyway.