Code Q&A: NEC Requirements for Installing MC Cable Attics or Roof Spaces

July 27, 2023

Test your knowledge of the NEC.

Q. What are the NEC requirements when installing MC cable in accessible attics or roof spaces?

See answer below.

A. Type MC cable installed in accessible attics or roof spaces must comply with Sec. 320.23.

Author’s Comment: On the Surface of Floor Joists, Rafters, or Studs. In attics and roof spaces that are accessible, substantial guards must protect cables installed across the top of floor joists, or across the face of rafters or studding within 7 ft of the floor or floor joists. If this space is not accessible by permanent stairs or ladders, protection is required only within 6 ft of the nearest edge of the scuttle hole or attic entrance [Sec. 320.23(A)].

Author’s Comment: Along the Side of Framing Members [Sec. 320.23(B)]. When Type MC cable is installed on the side of rafters, studs, or floor joists, no protection is required if the cable is installed at least 1¼ in. from the nearest edge of the framing member where nails or screws are likely to penetrate [Sec. 300.4(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.