Nec Illustrated Catastrophes 0720 Pr 5f19a51633352

Illustrated Catastrophes: Mismatched Wiring Methods

July 23, 2020

Think you know how these installations violate the NEC?

All references are based on the 2020 edition of the NEC.

Mismatched Wiring Methods

This photo was sent in by Jeremy Roland, vice president of West End Services, Inc., in Richmond, Va. “This was found on a bank-owned property,” says Roland. “We were doing a basic inspection before they put the home on the market. This is a receptacle under a covered porch. The plastic channel goes into the ceiling, so most likely they stripped the end of the NM and fished it down from above. We went no further as it was an inspection only. If we get approval to repair, I’ll send you more details.”We are looking forward to more photos from you, Jeremy. Using NM cable in damp or wet locations is prohibited by Sec. 334.12(B)(4). The metal connector is designed to be screwed into the inside of flexible metal conduit (FMC). Section 300.15 requires fittings and connectors to be used “only with the specific wiring methods for which they are designed and listed.” The type of cover used for the receptacle may have originally complied with Sec. 406.9(A) for damp locations, but now it is broken, so moisture can get inside the receptacle and cause damage.

Subpar Subpanel Feed

This photo was sent in by Eugene Lawrence with E-1 Electric LLC, in New Orleans. “We noticed this load center at a house in New Orleans,” says Lawrence. “We were called out to check on a job done by others. These photos show what we found. They were trying to feed a subpanel. As you can see, the feeder cable coming out of the conduit is connected to an added ‘wrong main’.”This was a great catch, Eugene. The original panelboard is not being used in a manner consistent for which it was designed and listed. Installing extra foot lugs on the bus bars and using circuit breakers from the wrong manufacturer violates the requirements of Sec. 110.3(B). The installers also failed to properly identify the grounded neutral conductor with white or gray as required in Sec. 200.6(B). Installing NM cables in PVC conduit located in an outdoor wet location such as this is a violation of Sec. 334.12(B)(4). Section 300.9 reminds us that “where raceways are installed in wet locations above grade, the interior of these raceways shall be considered to be a wet location.”

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.