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Code Q&A: NEC Requirements for Branch-Circuit Conductor Ampacity

Feb. 8, 2024

Test your knowledge of the NEC with this challenging question.

Courtesy of www.MikeHolt.com. Based on the 2023 NEC.

Question: Branch-circuit conductors supplying a single continuous-duty motor shall have an ampacity not less than _____ rating.

a) 125% of the motor’s nameplate current

b) 125% of the motor’s full-load current

c) 125% of the motor’s full locked-rotor

d) 80% of the motor’s full-load current

See answer below.

Answer: b) 125% of the motor’s full-load current

According to Sec. 430.22, "Condusctors that supply a single motor used in a continuous duty application shall have an ampacity of not less than 125% of the motor’s full-load current rating."

These materials are provided by Mike Holt Enterprises in Leesburg, Fla. To view Code training materials offered by this company, visit www.mikeholt.com/code.

About the Author

Mike Holt

Mike Holt is the owner of Mike Holt Enterprises (www.MikeHolt.com), one of the largest electrical publishers in the United States. He earned a master's degree in the Business Administration Program (MBA) from the University of Miami. He earned his reputation as a National Electrical Code (NEC) expert by working his way up through the electrical trade. Formally a construction editor for two different trade publications, Mike started his career as an apprentice electrician and eventually became a master electrician, an electrical inspector, a contractor, and an educator. Mike has taught more than 1,000 classes on 30 different electrical-related subjects — ranging from alarm installations to exam preparation and voltage drop calculations. He continues to produce seminars, videos, books, and online training for the trade as well as contribute monthly Code content to EC&M magazine.