All references are based on the 2017 edition of the NEC.
A CALL TO "ARMS"
This sign certainly got my attention as I was driving by. Unfortunately, it was for all the wrong reasons. It wasn’t the business name or the type of business that caught my eye. Instead, it was the poor design of the electrical installation used to illuminate the sign that got me excited enough to stop and take a closer look.
Those long bending “arms” extending out from the sign are PVC conduits that the installer used to support the lampholders. This is unquestionably a violation of Sec. 352.12(B), which states PVC conduit cannot be used “for the support of luminaires or other equipment not described in 352.10(H).” Lampholders are not described in Sec. 352.10(H). Conduit bodies are described in that Section of the Code. Section 352.10(H) reiterates that even these conduit bodies shall not be permitted to support luminaires or other equipment. The effects of gravity, wind, and snow will eventually cause these conduits to break or snap apart at the joints. Broken conduits with energized wires sticking out will then create a dangerous situation. This installation needs a complete do-over before that potential disaster becomes a reality.
PVC GROWING PAINS
This is an all-too-common sight. Broken PVC conduits on the outside of buildings can be spotted just by walking down the street or driving through town. In most of the problematic installations I spot, it’s often the installer who failed rather than the conduit itself.
The lack of expansion fittings as required by Sec. 352.44 is a common problem. The installation in the photo is another fine example of what can happen when electricians forget to install these important components in the conduit run. After several cycles of thermal expansion and contraction due to changes in air temperature and the heating effects of the sunlight, without a PVC expansion coupling to accommodate the length change of the conduit, the installation starts to self-destruct. Clips bend and break, couplings come unglued, and conduit bodies can break because of the extreme forces imposed on the conduit from the expansion and contraction. Per Table 352.44, a 100-ft run of PVC conduit installed where there will be a 75°F temperature change will experience a length change of more than 3 in. Section 352.44 requires expansion fittings where the length change of the conduit will be ¼ in. or more.
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.