Code Q&A: Overcurrent Protection Requirements for Appliance Circuits

Aug. 20, 2020

Test your knowledge of the NEC.

Q. What are the NEC branch circuit overcurrent protection requirements for appliance circuits?

See answer below.

A. (A) Branch Circuits.

Branch-circuit conductors must have overcurrent protection in accordance with Sec. 240.4, and the overcurrent protection device rating must not exceed the rating marked on the appliance [Sec. 422.11].

(E) Nonmotor Appliances.

The appliance overcurrent protection device must:

(1) Not exceed the rating marked on the appliance.

(2) Not exceed 20A if the overcurrent protection device rating isn’t marked, and the appliance is rated 13.30A or less, or

(3) Not exceed 150% of the appliance rated current if the overcurrent protection device rating isn’t marked, and the appliance is rated over 13.30A. Where 150% of the appliance rating doesn’t correspond to a standard overcurrent protection device ampere rating listed in Sec. 240.6(A), the next higher standard rating is permitted.

Example Problem: What’s the maximum size overcurrent protection device for a 4,500W, 240V water heater?

Solution: Protection Size = 4,500W ÷ 240V = 18.75A × 150% = 28A

Answer: 28A doesn’t correspond to a standard ampere rating, so use 30A which is the next size up [Sec. 240.6(A)].

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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.