Code Q&A

Nov 8, 2004 11:03 AM, By Mike Holt

Q. When is an insulating bushing required on raceway fittings?

A. Where raceways containing conductors 4 AWG and larger enter an enclosure, 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)].

Rigid nonmetallic conduit male-adapter termination fittings are sometimes considered to provide the required smooth rounded insulating surface. But check with the authority having jurisdiction (352.46).

One last thing: insulating bushings aren’t required where a raceway terminates in a threaded raceway entry that provides a smooth, rounded, or flared surface for the conductors. An example would be a meter hub fitting or a Meyer’s hub-type fitting [300.4(F) Ex.].

Got a Code question for Mike? Send it to him at mike@mikeholt.com.