The smallest branch circuit conductors that can be used for a 1-pole circuit breaker in a 120/240-volt panelboard are how many AWG?

For a single-pole circuit breaker in a 120/240-volt panelboard, the National Electrical Code (NEC) specifies that a minimum size of No. 14 AWG copper conductor is acceptable for circuits rated up to 15 amps. This is because No. 14 AWG wire can handle a maximum of 15 amps under standard configuration, making it suitable for typical household circuits that often use 15-amp breakers.

If the circuit requires a 20-amp breaker, the conductor size must increase to No. 12 AWG to ensure safe operation and prevent overheating. Choosing the appropriate wire size is crucial for maintaining effective electrical systems and ensuring that the wiring can carry the expected load without overheating or failing.

Conductors that are larger than No. 14 AWG, like No. 10 or smaller sizes, would be acceptable but would typically exceed the minimum requirements for circuits protected by 15-amp breakers. Thus, while larger wires might be used for specific applications or higher loads, the smallest acceptable size for a 15-amp circuit remains at No. 14 AWG.