Fig. 1. Examples of EMT uses not permitted by the NEC.

Stumped by the Code? NEC Requirements for Using and Installing EMT

Aug. 9, 2023

Answering your NEC questions

Mike Holt

Courtesy of www.MikeHolt.com

All questions and answers are based on the 2023 NEC.

Q: Under what conditions can EMT not be used and installed?

A: According to Sec. 358.12, EMT is not permitted to be used under the following conditions:

(1) Where subject to severe physical damage.

(2) For the support of luminaires or other equipment (Fig. 1).

Q: What is the minimum and maximum EMT trade size permitted?

A: The minimum and maximum EMT trade size permitted is stated in Sec. 358.20.

(A) Minimum. EMT smaller than trade size ½ is not permitted.

(B) Maximum. EMT larger than trade size 4 is not permitted.

Q: What are the requirements for securing and supporting EMT?

A: Section 358.30 gives the requirements for securing and supporting EMT.

EMT must be securely fastened in place and supported in accordance with (A) and (B).

(A) Securely Fastened. EMT must be securely fastened within 3 ft of every box, cabinet, or termination fitting, and at intervals not exceeding 10 ft.

Author’s Comment: Fastening is required within 3 ft of termination, not within 3 ft of a coupling.

Exception No. 1: When structural members do not permit the raceway to be secured within 3 ft of a box or termination fitting, an unbroken raceway can be secured within 5 ft of a box or termination fitting.

(B) Horizontal Runs. EMT installed horizontally in bored or punched holes in wood or metal framing members, or notches in wooden members at intervals not greater than 3 ft, is considered supported, but the raceway must be secured within 3 ft of termination (Fig. 2).

Fig. 2 Section 356.30)B) requirements for horizontal EMT runs. — **Fig. 2** Section 356.30)B) requirements for horizontal EMT runs.

These materials are provided 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.