By applying derating factors, you ensure that the wire operates well within its safe thermal limits, even in challenging conditions. Why is Wire Derating Necessary?
We look at the temperature correction table for 104°F (40°C). wire derating
At higher altitudes, air is less dense and provides less convective cooling, making it harder for wires to stay cool. The National Electrical Code (NEC) Requirements By applying derating factors, you ensure that the
Since 21.84 Amps is greater than 20 Amps, we can use this wire for a 20 Amp circuit. (If the calculation had resulted in 19 Amps, we would have had to downsize the breaker to 15 Amps or use larger wire). At higher altitudes, air is less dense and
Calculating the final safe current for a wire involves a simple multiplication process.
Imagine you have a (rated at 30A in the column of NEC Table 310.16 ).