Code Q&A

May 19, 2011

Q. When can power distribution blocks be installed in junction boxes?

A. Power distribution blocks installed in junction boxes over 100 cu. in. must comply with the following [314.28(E)], as shown in the Figure:

Installation. Be listed as a power distribution block.
Size. Be installed in a box not smaller than required by the installation instructions of the power distribution block.
Wire-bending space. The junction box is sized so that the wire-bending space requirements of 312.6 can be met.
Live parts. Exposed live parts on the power distribution block aren't present when the junction box cover is removed.
Through conductors. Where the junction box has conductors that don't terminate on the power distribution block(s), the through conductors must be arranged so the power distribution block terminals are unobstructed following installation.

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.