Underlined text indicates a change in the rules for the 2017 NEC.
Q. What are the NEC rules regarding mechanical continuity of raceways and cable sheaths?
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A. Raceways and cable sheaths must be mechanically continuous between boxes, cabinets, and fittings [300.12].
Exception No. 1: Short sections of raceways used to provide support or protection of cable from physical damage aren’t required to be mechanically continuous [250.86 Ex 2 and 300.10 Ex 1].
Exception No. 2: Raceways at the bottom of open‑bottom equipment, such as switchboards, motor control centers, and transformers, aren’t required to be mechanically secured to the equipment.
When raceways are stubbed into an open‑bottom switchboard, the raceway, including the end fitting, can’t rise more than 3 in. above the bottom of the switchboard enclosure [408.5].
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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.