What's Wrong Here?

What’s Wrong Here? Hint: A Close Call at the Ceiling

Jan. 26, 2023

Think you know how this installation violates the NEC?

Hint: A close call at the ceiling

NM cable installed directly beneath metal corrugated roof

A few more inches left or right could have spelled disaster for this NM cable installed directly beneath the metal corrugated roof. There is one long screw that penetrated the roof in very close proximity to this cable. Section 300.4(E) prohibits cables, raceways, and boxes from being installed less than 1½ in. from the lowest portion of the metal-corrugated roof decking. I’m assuming the piece of cardboard folded around the NM cable where the cable crosses the metal I-beam was an attempt to provide some type of protection from abrasion or pinching of the cable. There are much better options than cardboard for providing protection for cables including bushings, grommets, and protective raceway sleeves.

About the Author

Russ LeBlanc | Owner

Russ started in the electrical trade as an apprentice in 1985. He worked his way up to become a Journeyman Electrician and then eventually became a Master Electrician and Licensed Construction Supervisor. In 1999 Russ become an Electrical Instructor for The Peterson School of Engineering in Massachusetts where he developed his passion for teaching, and quickly became Department Head of Electrical Instruction. Russ has taught thousands of apprentices, electricians, engineers, inspectors, and other electrical professionals during his career as an instructor. He continues to provide electrical professionals with Electrical Code seminars, Arc-Flash Awareness training seminars and educational material through his LeBlanc Consulting Services in North Reading, MA whose specialty is educating electricians. He has been an active member of the NFPA Electrical Section and has authored hundreds of National Electrical Code proposals and comments which have become Code rules to improve the safety for the electrical industry. Russ is also an IAEI certified Electrical Inspector.

Please visit www.russleblanc.net for more information.