ECN Forum Forums Code Related Discussion NEC & other Code issues Bushings on RMC

Hello Guys and Gals:

Just wanted to see what the prevailing opinion is concerning 2005 NEC 344.46.

I feel this states that all RMC entering a box, etc. requires a bushing. This is also the way I have always installed RMC.(even when it was called GRC

Several other inspectors disagree and believe the FPN referring to 300.4(F) indicates this is only true for #4 and larger.

I believe the Code panels do not repeat themselves and the FPN is simply a way to give additional information regarding wires #4 and larger and has nothing to do with the requirement for bushings on all RMC.

FWIW The situation is a new installation with multiple 3/4" RMC stubs into the bottom of several panels. The number is close to 50, so it would be a large amount of re-work to install the bushings as these panels are hot and the building is almost ready for occupancy.

Thanks,

Jim

Jim I agree with you.


It seems pretty clear to me that all RMC will have bushings regardless of wire size.

The same can be said off RNC.


and IMC


I can't see how these sections could be misunderstood.

As I read it, a bushing is required for _all_ RMC entering a box, but that for conductors #4 or larger a smoothly rounded _insulating_ surface must be provided. Presumably a _conductive_ bushing is permitted for conductors smaller than #4 as long at it appropriately protects the insulation.

Of course the font of all knowledge (google) provides a discussion of the solution in Mike Holt's forum: http://www.mikeholt.com/cgi-bin/codeforum/ultimatebb.cgi?ubb=get_topic;f=11;t=008514;p=

Arlington Adjustable Throat Liner http://www.aifittings.com/m_6.htm

-Jon

The head electrical inspector for this state(not mine) has determined that bushings are not required for smaller than #4.

Everyone else I spoke with about this agrees with us.

Thanks for the confirmation, guys!
Jim

The #4 threshhold is specifically for EMT and other such raceways.

RMC, IMC, etc. require bushings up and down their range: there are no exceptions: 344.46.

300.4F Handbook detail lays this all out.