Insulated bushings

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iceman2610

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I engaged in a discussion about the NEC with a friend the other day. We disagreed on the requirements of the use of insulated bushing nuts. He believed that any conduit or fitting (including a romex connector) 3/4" or larger required an insulated bushing nut. I understand the code (section 300.4(f)) to require an insulated bushing on conduit fitings only to protect conductors of 4 AWG and larger, and sections 342.46, 344.46, & 362.46 to require a bushing on all conduit entering a box unless the box or fitting is designed to provide the same protection. I do not believe EMT fittings or Romex connectors require a bushing nut unless it would contain a 4 AWG or larger conductor.


Anyone with any thoughts on this matter.
Code:
 
Re: Insulated bushings

I agree that 4 AWG and bigger should have a bushing installed on the threads of conduit, this is what I have read in the NEC code book myself and understood,
when I went to put a bushing on some 2 AWG coming from a SE cable into the main panel the guy in charge got all hyper and said that we never use them on SE cable !!!!

So I said when would you use them ???

He never really answered because he don't know were they should be used and is a dope about such issues,

The best I can say is 4 Awg and larger wire would require a bushing on the threads of the conduit.
 
Re: Insulated bushings

Agreed, 4 awg and larger. Bushings should be used with any size wire with IMC and RMC
where it enters a box, fitting, or other enclosure
unless the box, fitting, or enclosure affords the
equivalent protection.
 
Re: Insulated bushings

Don't know why;

300.4(F) requires INSULATED bushing(s) for 4 AWG and larger.

344.46 and 342.46 requires a bushing on all conduit ends unless the box (usually hubbed boxes) provide the smoothness ( non abrasion ).

358. does not have a .46 .

So, non-insulated bushings on IMC and RMC conduits with less than size 5 AWG conductors is permitted, but a bushing is still required.
 
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