Code Q&A: Surface Extensions

Q. What is the Code rule regarding the installation of surface extensions from a box or box cover?

July 5, 2018

Q. What is the Code rule regarding the installation of surface extensions from a box or box cover?

See the answer below.

This answer is based on the 2017 NEC.

A. Surface extensions can only be made from an extension ring installed over a box [Sec. 314.22].

Exception: A surface extension can be made from the cover of a box if the cover is designed so it’s unlikely to fall off if the mounting screws become loose. The surface extension wiring method must be flexible to permit the removal of the cover and provide access to the box interior, and equipment grounding continuity must be independent of the connection between the box and the cover.

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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.