Illustrated Catastrophes: Dangerous Curves Ahead!
All references are based on the 2026 edition of the NEC.
Dangerous Curves Ahead!
This UF cable looks like it was squeezed in a vise to make that bend. The bend is way too sharp. Section 340.24 requires bends in UF cable to be made so the cable is not damaged. Any bends must be made so the curve radius of the inner edge of the bend is not less than five times the diameter of the cable. For flat (elliptical) cables, the minor dimension can be used when bending on the flat side. For example, a 0.195 in. × 0.415 in. cable needs a bending radius of 0.195 in. × 5 = 0.975 in. when bending on the flat side. This translates to a bend with a diameter of 1.95 in. For comparison, a standard golf ball has a diameter of approximately 1.68 in.
Another problem is all of the limited energy (communication) cables that are secured to the UF cable. Section 300.13 prohibits using cable wiring methods as a means of support for other cables, conductors, raceways, or nonelectrical equipment. For limited energy cables, Sec. 720.30(D) also prohibits using cable wiring methods as a means of support for cables, raceways, or non-electrical equipment.
What’s Not Wrong Here?
There are so many violations here that it may be easier for me to explain what’s right with this installation rather than what’s wrong. But let’s stick with the normal format and focus on what’s wrong. None of the NM cables are secured within 12 in. of the box as required by Sec. 334.30. The yellow 12/2 NM cable curling up to the right side is not mechanically secured to the box as required by Sec. 300.14. The equipment grounding conductor (EGC) of that same 12/2 cable is wrapped back around the cable jacket and is not connected to the EGCs of the other cables or to the metal box as required by Sec. 250.148. The missing cover for the box is a violation of Sec. 314.25. Lastly, there is a knockout seal missing from the bottom knockout on the left side of the box. Section 110.12(A) requires unused openings to be closed in a manner that affords protection substantially equivalent to the wall of the equipment.
About the Author
Russ LeBlancRuss 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.
