Q. When does the Code allow Type NM cable to be spliced using NM cable interconnection devices?
See the answer below.
This answer is based on the 2017 NEC.
A. A box or conduit body isn’t required where a listed nonmetallic-sheathed cable interconnector device is used for any exposed cable wiring or for concealed cable wiring in existing buildings in accordance with Sec. 300.15(H) [334.40].
Per UL (QAAV), interconnection devices have been investigated for equivalency to Type NM cable in insulation and temperature rise, and for capability to withstand fault currents, vibration, and mechanical shock that may occur during transport. The interconnects are intended for use with 14 AWG and 12 AWG solid or stranded copper conductors.
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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.