questionable box support

What’s Wrong Here? Hint: Questionable Box Support

Oct. 26, 2023
Think you know how this installation violates the NEC?

Hint: Questionable box support

I’m not so sure the boxes installed here are properly supported in accordance with the requirements Sec. 314.23(F) Exception No. 2. Specifically, Condition 2 is where the problem seems to be. One unbroken length of IMC or RMC is permitted to support a box for a luminaire where six conditions are met. Condition 1 limits the conduit length to 3 ft beyond the last conduit support. There is no problem with the conduit length here. Condition 2 requires an unbroken length of conduit before the last conduit support to be 12 in. or greater in length, and that portion of conduit must be securely fastened no less than 12 in. from its last point of support. Condition 2 seems problematic for this installation. Condition 3 requires the luminaire to be at least 8 ft above the public sidewalk below. Not a problem here. The luminaires don’t exceed 12 in. as specified in Condition 4. The weight of these luminaires certainly complies with the 20-lb limit of Condition 5. The luminaires appear to be securely threaded into the box as required by Condition 6. All in all, it is a pretty good installation other than questionable compliance with Condition 2.

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 for more information.

Voice your opinion!

To join the conversation, and become an exclusive member of EC&M, create an account today!

Sponsored Recommendations

Comparison Chart

Champion Fiberglass electrical conduit is a lightweight, durable option that provides lasting savings when compared to other materials. Compare elect…

Video Installation Guides

These video guides offer two-minute overviews to the most common Champion Fiberglass installations in easy-to-follow, step-by-step instructions.. Fiel…