Identify an appropriate size of wire for a 20 amp circuit.

For a 20 amp circuit, the appropriate wire size is 12 AWG (American Wire Gauge). This wire size is commonly used for circuit breakers rated at 20 amps according to the National Electrical Code (NEC). The selection of wire size is critical because it must be able to safely handle the current without overheating, which can pose fire hazards.

12 AWG wire has a sufficient ampacity for a 20 amp circuit, meaning it can carry the current effectively without exceeding its maximum temperature rating. In practical applications, using 12 AWG ensures that the wire can handle continuous loads and provides a margin of safety.

Wire sizes larger than 12 AWG, such as 10 AWG, may also work for 20 amps but are typically not required for this specific circuit load and are less common. On the other hand, sizes below 12 AWG, such as 14 AWG or 16 AWG, do not meet the minimum requirement for a 20 amp circuit and would be unsafe, as they could overheat and potentially lead to electrical fires if subjected to this amount of current.