Nipple rule

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Dbronx

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I have a 18 X 18 junction box and I want to nipple down into a panel. I want to use a LR out of junction box then and then 16 inch pvc conduit. The total lenght is 21 inches, I was told the 25 inch nipple rule can not because the use of a LR.
 
Are you asking about conduit fill {60% for nipples 24" or less} or derating {nipples more than 24"}.
 
IMO, the LR would count as part of the 24" nipple maximum length. However, it is not clear in the NEC- that would be an ahj call.
 
Dennis Alwon said:
IMO, the LR would count as part of the 24" nipple maximum length. However, it is not clear in the NEC- that would be an ahj call.
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There you go being logical again. :D

I'm not so sure that you will find the words in the NEC to make that opinion enforceable.
 
infinity said:
There you go being logical again. :D

I'm not so sure that you will find the words in the NEC to make that opinion enforceable.
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I don't think the words are there to go against his opinion either.

If anything you have a conduit body that really has no fill limitation other than the fill of the connected raceways, as long as the conduit body has no splices or taps in it anyway, and two separate nipples both less than 24 inches. You also have a length of conductors in raceways or bundled or combination of both that is still less than 24 inches total.

I say fill it to 60% and don't bother with ampacity adjustments, both are allowed.

Add; One potential fill condition for the conduit body may be bending space for larger conductors.
 
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The OP said the total length is 21" so for most of the info in this thread the point is moot. :roll:

We still don't know exactly what the question is. :D
 
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iwire said:
You mean other than the fact one is listed as a raceway or nipple and the other is listed as a conduit body?
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Exactly. Replace conduit body with junction box - we still have two short nipples with a box or conduit body between them. A conduit body and a junction box are the same when it comes dealing with raceway fill or ampacity adjustments, you could also interchange them with a cabinet, cut out box, meter socket, outlet/device box, or handhole enclosure for that matter, and it still won't change your conduit fill or ampacity adjustments.

So conduit fill IMO is definitely going to fall into the 60% rate for nipples shorter than 24". Ampacity adjustments, could be trickier, but if total length of "bundled" conductors is still 24" or less I don't think adjustments are necessary.
 
There is no provision to permit a 60% fill of the conduit body. See 314.16(C)(1). (assuming the conduit body is of the same trade size as the conduit)
 
don_resqcapt19 said:
There is no provision to permit a 60% fill of the conduit body. See 314.16(C)(1). (assuming the conduit body is of the same trade size as the conduit)
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I think assuming same trade size as the conduit - 314.16(C)(1) sends you to ch9 table 1 for fill. If the raceway can take the fill why can't the conduit body, it is kind of an extension of the raceway, yet is also not a raceway.
 
kwired said:
I think assuming same trade size as the conduit - 314.16(C)(1) sends you to ch9 table 1 for fill. If the raceway can take the fill why can't the conduit body, it is kind of an extension of the raceway, yet is also not a raceway.
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Because it is not a nipple. :D
 
A conduit body is not a nipple. Therefore, you cannot use the 24" nipple rule.

However, with that logic there is no reason you could not wire something up using a series of 24" nipples and conduit bodies of any length as long as you derated properly inside the conduit bodies, but no derating would be required inside the nipples.
 
kwired said:
I think assuming same trade size as the conduit - 314.16(C)(1) sends you to ch9 table 1 for fill. If the raceway can take the fill why can't the conduit body, it is kind of an extension of the raceway, yet is also not a raceway.
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I think we are back to the debate about how many and what size conductors can go in a conduit body.
 
Can I fill a 100 foot run of RMC to 60% if there is a coupling every 24"? Do I have 100' of RMC or do I have 50 - 24" nipples?

If I hit a conduit body with no splices or taps, is it a continuation of a raceway or "nipple" or is it "something other than a raceway or nipple between two raceways and/or nipples?

If I replace conduit body with a junction box, is the fact that I still have nipples on either side of whatever is in the middle changed any?




This is starting to sound like inappropriate material here:)
 
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