NEC Wire Ampacity Reference (Table 310.16)

NEC Table 310.16 is the go-to reference for allowable ampacities of insulated conductors not more than three current-carrying conductors in a raceway, cable, or earth. The values below are for copper conductors at 75 degrees C insulation rating, which is the standard for most residential and commercial installations.

Copper Conductor Ampacity (75 degrees C, up to 3 conductors)

Wire Gauge (AWG)	Ampacity (75C)	Common Use
14 AWG	20A	Lighting circuits, general outlets
12 AWG	25A	General outlets, small appliances
10 AWG	35A	Dryers, water heaters (small)
8 AWG	50A	Electric ranges, dryers
6 AWG	65A	Sub-panels, AC units
4 AWG	85A	Sub-panels, large AC units
3 AWG	100A	Service entrance (small), sub-panels
2 AWG	115A	Service entrance, large sub-panels
1 AWG	130A	Service entrance
1/0 AWG	150A	Service entrance, feeders
2/0 AWG	175A	Service entrance
3/0 AWG	200A	Service entrance (200A service)
4/0 AWG	230A	Large service entrance
250 kcmil	255A	Commercial feeders
300 kcmil	285A	Commercial feeders
400 kcmil	335A	Commercial feeders

Key Rules to Remember

80% Rule for Continuous Loads: NEC 210.20(A) requires that branch circuit conductors have ampacity not less than 125% of the continuous load plus 100% of non-continuous load. In practice, if you have a continuous load, multiply it by 1.25 before looking up the wire size.

Aluminum Derating: Aluminum conductors have lower ampacity than copper of the same gauge. For aluminum at 75C, subtract roughly 20-25% from the copper values, or go up 2 wire sizes (e.g., use 2/0 aluminum where 1 AWG copper would work).

Conduit Fill: These values assume no more than three current-carrying conductors. If you have more, apply the adjustment factors in NEC Table 310.15(C)(1).

Reference

NEC Table 310.16, 2023 edition. Always verify with your local adopted code version and having a licensed electrician review your work.