Code Q&A: Accounting for Thermal Expansion of Cable Tray

Test your NEC knowledge.

Sept. 9, 2021

Based on the 2020 NEC.

Q. What does the Code require to compensate for the thermal expansion of a cable tray?

See answer below.

A. Expansion splice plates for cable trays must be provided where necessary to compensate for thermal expansion and contraction [Sec. 392.44]. Thermal expansion is often overlooked and can be a problem without the installation of raceway expansion joints. For the raceway to properly serve its function, it must be able to expand, as well as contract, and expansion joints provide the ability to do so.

This Code section gives no guidance on how to determine the need for an expansion splice plate but there is a National Electrical Manufacturer’s Association (NEMA) document available as a free download that may assist. This document is titled; “NEMA VE2, Cable Tray Installation Guidelines.”

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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.