Q. What are the requirements when installing 15A, 125V duplex receptacles on a 20A, 120V circuit?
A. There are many rules found in 210.21(B), which covers receptacle ratings and loading. A single receptacle on an individual branch circuit must have an ampacity not less than the rating of the overcurrent device. FPN: A single receptacle has only one contact device on its yoke [Art. 100]. This means a duplex receptacle is considered two receptacles.
Where connected to a branch circuit that supplies two or more receptacles, the total cord- and plug-connected load must not exceed 80% of the receptacle rating. A duplex receptacle has two contact devices on the same yoke [Art. 100]. This means even one duplex receptacle on a circuit makes that circuit a multi-outlet branch circuit.
Where connected to a branch circuit that supplies two or more receptacles, receptacles must have an ampere rating in accordance with the values listed in Table 210.21(B)(3).
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.