Short nipples

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JoeNorm

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Let's say I have a gutter with a panel directly above it. If I use short nipples as wireways do I need lock nuts on both sides of each enclosure? If the answer is yes that means 4 locknuts per nipple? Code reference, please.

Also wondering if each nipple needs a ground wire run through it if there are conductors within. There would be a groundbar in the gutter but does each nipple need a ground? I have a recollection of a code saying each pipe needs a ground wire, is this true for short paths between enclosures?

thanks
 
Yes, in general, you need locknuts on both sides of the enclosure. As far as what else may be required and the code reference will depend on the situation, IE voltage, concentric KOs, whether these are service conductors, etc.
 
2nd question, 300.3(B) and 300.3(B)(1). Probably some other variables, but these would be good starters.
 
I agree locknuts on both sides of the KO are required. If you used a chase nipple or a short piece of running thread with no space between the enclosure and wireway then IMO one locknut on the chase nipple or one on each side with the running thread would be sufficient.
 
infinity said:
I agree locknuts on both sides of the KO are required. If you used a chase nipple or a short piece of running thread with no space between the enclosure and wireway then IMO one locknut on the chase nipple or one on each side with the running thread would be sufficient.
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Suppose you already had bonding bushings on both ends of the nipple. Would you also need locknuts for the exterior of the enclosures on the nipple for the mechanical purpose of the locknuts?
 
Carultch said:
Suppose you already had bonding bushings on both ends of the nipple. Would you also need locknuts for the exterior of the enclosures on the nipple for the mechanical purpose of the locknuts?
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Are you saying bonding bushings with no locknuts? If you had a locknut on the outside then yes only a metal bushing could be on the inside. That was the SOP for deck boxes with the RMC buried in the concrete for decades. We would put a locknut on end, insert in KO, steel bushing on inside, tighten locknut on the outside.
 
Thanks for the replies. After reviewing the code I am still unclear on this. For the first question it just says the enclosure and raceway has to be made continuous. It doesn't say exactly how that's done and how locknuts are to be used. Am I missing something?
 
infinity said:
Are you saying bonding bushings with no locknuts? If you had a locknut on the outside then yes only a metal bushing could be on the inside. That was the SOP for deck boxes with the RMC buried in the concrete for decades. We would put a locknut on end, insert in KO, steel bushing on inside, tighten locknut on the outside.
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No. I'm aware that metal bushings (but not plastic bushings) can double as the locknuts inside the enclosure, and serve the mechanical purpose of the locknuts on the inside of the enclosure. Sometimes it is a necessity when you have a thick plastic box, and not enough connector threads remaining for both the locknut and bonding bushing to attach.

What I'm asking about, is whether the locknuts between the two enclosures would be needed. The inner locknuts on the nipple assembly, that would face outward toward the exterior of the enclosure walls, that the OP was originally asking about.
 
I don't see any general rule in the NEC that specifically requires two locknuts at a conduit termination.
 
Maybe in the eyes of interpretation. Referenced again in 250.92(B) and 250.97(2). And if you consider the language in 250.97(3) where the fitting is shouldered? It seems pretty cut and dry to me why you would use 2.
 
But say bonding is not an issue, such as because there is a bonding bushing used.
I would refer you back to post #3 where 300.10 and 300.11 are referenced. My humble interpretation of those two sections imply that it will take 2 locknuts to accomplish this. Please provide reference where only 1 is acceptable?
 
Greentagger said:
But say bonding is not an issue, such as because there is a bonding bushing used.
I would refer you back to post #3 where 300.10 and 300.11 are referenced. My humble interpretation of those two sections imply that it will take 2 locknuts to accomplish this. Please provide reference where only 1 is acceptable?
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The bonding bushing takes care of the 300.10 issue and with a short nipple between two fixed enclosures, a single locknut inside each enclosure securely holds the conduit in place, and in addition the xxx.30 section for that raceway also require a strap or other securing and supporting device.

This become a judgement call. There is no general code reference that requires two locknuts. There are specific requirements in some of the Chapter 5 Articles, for example 551.47(B) and 552.48(B).
 
I wonder why fittings have shoulders on them, some be it small, but all fittings have some type of shoulder on them? Maybe to comply with 300.11(A).? I wonder if that would be similar or the same as a rigid nipple having 2 lock nuts, 1 on the inside and 1 on the outside? Noted on the steel tubing installation guide that 2 lock nuts would satisfy 300.11(A). Food for thought.
 
It has double lock nut and plastic bushing to the left. Single lock nut inside enclouser and plastic bushing on the right. No locknut outside of enclouser right. Maybe legal but bad workmanship in my eyes.
 
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