According to NEC, what is the smallest wire size for a 20 amp circuit?

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Multiple Choice

According to NEC, what is the smallest wire size for a 20 amp circuit?

Explanation:
Sizing conductors to the circuit’s overcurrent protection is the key idea. NEC requires the conductor’s ampacity to be at least the rating of the overcurrent device on the circuit. For a 20-amp circuit, the conductor must be able to carry 20 amps. Among common copper options, 14 AWG is rated for 15 amps, so it cannot be used on a 20-amp circuit. 12 AWG copper is rated for 20 amps, making it the smallest size that meets the requirement. Using larger sizes like 10 AWG or 8 AWG is allowed but not necessary to meet the 20-amp limit; they’re simply bigger than needed. In typical residential wiring (NM-B), 12 AWG is the standard minimum for a 20-amp circuit.

Sizing conductors to the circuit’s overcurrent protection is the key idea. NEC requires the conductor’s ampacity to be at least the rating of the overcurrent device on the circuit. For a 20-amp circuit, the conductor must be able to carry 20 amps. Among common copper options, 14 AWG is rated for 15 amps, so it cannot be used on a 20-amp circuit. 12 AWG copper is rated for 20 amps, making it the smallest size that meets the requirement. Using larger sizes like 10 AWG or 8 AWG is allowed but not necessary to meet the 20-amp limit; they’re simply bigger than needed. In typical residential wiring (NM-B), 12 AWG is the standard minimum for a 20-amp circuit.

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