20A

20A is a designation used in electrical engineering to indicate a current rating of twenty amperes. It appears on circuit breakers, fuses, outlets, extension cords, and other equipment to specify the maximum continuous current the device is designed to carry. The 20A rating is part of standards used to protect wiring from overheating and to ensure safety in electrical installations.

In residential North American electrical systems, 20A circuits are common alongside 15A circuits. A 20A circuit is typically protected by a 20A breaker and is wired with copper conductors of at least 12 AWG; conductors smaller than 12 AWG (for example 14 AWG) are not allowed on 20A circuits. The common receptacle used on a 20A circuit is the NEMA 5-20R, which is designed to accept 20A plugs and is also compatible with standard 15A plugs.

Theoretical maximum power on a 20A circuit depends on voltage. At 120V, a 20A circuit can deliver up to about 2,400 watts. At 230V, the same current rating would permit up to about 4,600 watts. In practice, actual usable power depends on the specific wiring, protective devices, and connected loads, and it should never exceed the rating of the circuit or individual components.

Across other contexts, 20A may also appear on fuses, power strips, or equipment labeling to denote the maximum current they can safely handle. The designation is simply a rating and must be observed to maintain electrical safety.