Chase nipple

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Dennis Alwon said:
Remember the discussion about 24" raceway and someone brought up the fact that an LB is not a raceway but a fitting so you could have 24" of raceway plus the LB. Well that question was presented at a meeting a a CMP member said the LB was an extension of that raceway so de rating must be used.

I think we need to use common sense here- I know the code doesn't always do this- A chase nipple is no different than any other raceway so why would that be an issue. The reason is for overheating..... JMO
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I agree, but the question of which raceway table applies to the cross sectional area of the chase nipple still has not been answered.
 
Dennis Alwon said:
Why is that info necessary?
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What do you derive the 60% fill from? Are we supposed to get out micrometers and measure them ourselves? What if inspector questions your measurement? Ch 9 tables give us dimensions for the raceways mentioned, there is no question what dimension applies in those instances.
 
Okay I think I see what the issue is but not sure I would loose sleep over the differences. Interesting point tho.....
 
Dennis Alwon said:
Okay I think I see what the issue is but not sure I would loose sleep over the differences. Interesting point tho.....
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Before they put a table in Ch 9 for every raceway type I would have said just base the fill on the trade size like we did with everything else, but since the NEC feels the small difference in size between different sizes of nominal sized raceways makes that much difference that it is necessary to essentially publish an extra chapter in the book to contain all that information... how did we ever get by before they did that??
 
Well, it has to be included in one of the methods, had to argue that RMC is not the one. I would accept it as either the conduit itself. Or as an associated fitting, though I expect to put one bushing on it. Two bushings on an offset nipple.

NEC said:
344.2 Definition.
Rigid Metal Conduit (RMC). A threadable raceway of circular cross section designed for the physical protection and routing of conductors and cables and for use as an equipment grounding conductor when installed with its integral or associated coupling and appropriate fittings. RMC is generally made of steel (ferrous) with protective coatings or aluminum (nonferrous). Special use types are red brass and stainless steel.

344.6 Listing Requirements. RMC, factory elbows and
couplings, and associated fittings shall be listed.
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And while I'm all for strict interpretation, don't read 344.2 too closely or you'll find that RMC is not allowed to be used without a coupling.
 
Volta said:
And while I'm all for strict interpretation, don't read 344.2 too closely or you'll find that RMC is not allowed to be used without a coupling.
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IMHO, all that says is that you cannot use it as an EGC if you do not use the listed couplings and fittings. Not that they have to be there when all it is used for is protection.
Wording like this needs to have parentheses in it to bracket together the logical relationships. :rant:
Otherwise the disputes will never end.
 
GoldDigger said:
IMHO, all that says is that you cannot use it as an EGC if you do not use the listed couplings and fittings. Not that they have to be there when all it is used for is protection.
Wording like this needs to have parentheses in it to bracket together the logical relationships. :rant:
Otherwise the disputes will never end.
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Oh, I think it is pretty easy- the conjunction they chose to use is 'and'.

Anyhow I'm not debating it, and I similarly doubt that you interpret it to mean it isn't a grounding path without a coupling.

I am really saying the opposite, that we should read it precisely as written until something is shown to be silly or unclear, then try to tease out the real intent.
 
Volta said:
=
I am really saying the opposite, that we should read it precisely as written until something is shown to be silly or unclear, then try to tease out the real intent.
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Since they did not put a comma before the "when", the natural scope of the "when" clause is only the second half of the "and". To me, that is precisely how it was written.
It they meant it to apply to both, they should have put the when clause first. :)
 
GoldDigger said:
Since they did not put a comma before the "when", the natural scope of the "when" clause is only the second half of the "and". To me, that is precisely how it was written.
It they meant it to apply to both, they should have put the when clause first. :)
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Maybe, are you saying an that unbroken nipple does not qualify as a grounding conductor; that a coupling is required?
 
Volta said:
Maybe, are you saying an that unbroken nipple does not qualify as a grounding conductor; that a coupling is required?
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Not necessarily. There does not have to be coupling in the middle, but there have to be integral or listed terminating devices on each end for it to be used as a ground. Without something to bond to or to bond it to a box or other component, it is not much use as a ground. And whatever devices serve that function must be listed for that purpose.

Looking at it in the light of first part of the sentence, you can use it as protection for wires with any sort of coupling that provides mechanical integrity. You could even use a plastic coupling if it is allowed in the area where the RMC is running. But if that is all you do, you will only have protection for the wires. To elevate its functioning to be a ground, listed components have to be used from one end to the other of its path.
 
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