What is the maximum rating (as a percentage of the branch circuit rating) of any one cord-and-plug connected utilization equipment on a 15-amp branch circuit?

What is the maximum rating (as a percentage of the branch circuit rating) of any one cord-and-plug connected utilization equipment on a 15-amp branch circuit?

• A. 80%
• B. 60%
• C. 100%
• D. 120%

Answer: (A)

The limit is 80% of the branch-circuit rating for any one cord-and-plug connected utilization equipment. This 80% rule gives a safety margin for loads that may run for extended periods, helping keep conductors and overcurrent devices from overheating and preventing nuisance trips. On a 15-amp circuit, 80% equals 12 amps, which is about 1,440 watts at 120 volts. So the maximum rating for a single cord-and-plug connected device on that circuit is 12 amps (80% of 15 amps).

The limit is 80% of the branch-circuit rating for any one cord-and-plug connected utilization equipment. This 80% rule gives a safety margin for loads that may run for extended periods, helping keep conductors and overcurrent devices from overheating and preventing nuisance trips. On a 15-amp circuit, 80% equals 12 amps, which is about 1,440 watts at 120 volts. So the maximum rating for a single cord-and-plug connected device on that circuit is 12 amps (80% of 15 amps).