Code Q&A

Oct. 12, 2007

When are insulated bushings required on raceway terminations?

Q. When are insulated bushings required on raceway terminations?

A. Where raceways contain conductors 4 AWG and larger, the conductors must be protected from abrasion during and after installation by a fitting that provides a smooth, rounded insulating surface, such as an insulating bushing [300.4(F)]. For IMC and RMC, a metal or plastic bushing must be installed on conduit threads at terminations, regardless of conductor size, in accordance with 300.4(F), unless the design of the box, fitting, or enclosure is such as to afford equivalent protection [342.46 and 344.46].

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.