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Code Q&A: Conductors in Parallel

Aug. 22, 2019

Test your NEC knowledge.

Q. What are the Code rules for the installation of single or parallel conductors in cable trays?

See the answer below.

A. To prevent unbalanced current in the parallel conductors due to inductive reactance, all circuit conductors of a parallel set [Sec. 310.10(H)] must be bundled together and secured to prevent excessive movement due to fault-current magnetic forces [Sec. 392.20 (C)].

Single conductors of a circuit not connected in parallel must be installed in a single layer, unless the conductors are bound together [Sec. 392.20(D)].

These materials are provided to us by Mike Holt Enterprises in Leesburg, Fla. To view Code training materials offered by this company, visit www.mikeholt.com/code.

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.