The term ampacity refers to what characteristic of a conductor in feeder sizing?

• A. The current-carrying capacity of the conductor
• B. The physical size of the conductor
• C. The conductor insulation type
• D. The conductor color code

Answer: (A)

Ampacity is the maximum current a conductor can carry continuously without overheating beyond its insulation’s temperature rating in a given installation. In feeder sizing, you choose a conductor whose ampacity meets the expected load, applying derating for ambient temperature, the number of conductors in a raceway or bundle, and any continuous-load adjustments (often 125% for continuous loads). The physical size of the conductor is related to how much current it can carry, but it’s not the definition itself; the insulation type and temperature rating determine how much current is safe, and color code is just for identification.