Current Capacity (Ampacity)

Ampacity is the maximum current a conductor can carry continuously under the conditions of use without exceeding its temperature rating.

NEC Allowable Ampacities (Copper, 30°C Ambient)

Based on Table 310.16. Not more than three current-carrying conductors in raceway.

AWG	60°C (TW, UF)	75°C (THHW, THWN)	90°C (THHN, XHHW-2)
14	15 A	20 A	25 A
12	20 A	25 A	30 A
10	30 A	35 A	40 A
8	40 A	50 A	55 A
6	55 A	65 A	75 A
4	70 A	85 A	95 A

Correction Factors

• Ambient Temperature: If ambient exceeds 30°C, ampacity must be derated.
• Bundle Count: If more than 3 current-carrying conductors are bundled, ampacity drops (4-6 conductors = 80%).
• Continuous Load: For continuous loads (≥3 hours), circuits must be sized for 125% of the load.