$100 \text Amps / 0.72 = 139 \text Amps$
$0.90 \times 0.80 = 0.72$
The derating factor is a multiplier, usually less than 1, applied to the nominal current-carrying capacity of a cable. It adjusts the rated capacity downward to account for environmental and installation conditions that differ from the standard reference conditions. derating factor of cable
Scenario: A cable buried in thick thermal insulation might have its capacity slashed in half (factor of ). The "Magic" of the Calculation
Heat dissipation is driven by the temperature difference between the conductor and the surrounding medium. Higher ambient temperature reduces this gradient. $100 \text Amps / 0
Several variables dictate the specific derating factor for an installation. The most common include:
If your environment is hotter than the standard 30∘C30 raised to the composed with power C The "Magic" of the Calculation Heat dissipation is
Scenario: Pack 6–15 wires into one bundle, and you might have to derate to . Now that 87A capacity drops to 60.9A .
When you run multiple cables together in a tight tray or conduit, they "mutually heat" each other.