Code Q&A: Conductor Feed Through

July 19, 2012

Your most pressing National Electrical Code (NEC) questions answered

Q. What are the requirements when running conductors through one panel cabinet to feed another panel?

A. Cabinets, cutout boxes, and meter socket enclosures can be used for conductors as feeding through, spliced, or tapping off to other enclosures, switches, or overcurrent devices where all of the following conditions are met [312.8]:

The total area of the conductors at any cross section doesn't exceed 40% of the cross-sectional area of the space.
The total area of conductors, splices, and taps installed at any cross section doesn't exceed 75% of the cross-sectional area of that space.
A warning label on the enclosure identifies the disconnecting means for feed-through conductors.

About the Author

Mike Holt

Mike Holt is the owner of Mike Holt Enterprises (www.MikeHolt.com), one of the largest electrical publishers in the United States. He earned a master's degree in the Business Administration Program (MBA) from the University of Miami. He earned his reputation as a National Electrical Code (NEC) expert by working his way up through the electrical trade. Formally a construction editor for two different trade publications, Mike started his career as an apprentice electrician and eventually became a master electrician, an electrical inspector, a contractor, and an educator. Mike has taught more than 1,000 classes on 30 different electrical-related subjects — ranging from alarm installations to exam preparation and voltage drop calculations. He continues to produce seminars, videos, books, and online training for the trade as well as contribute monthly Code content to EC&M magazine.