310.4 and the powers that be.

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chris kennedy

chris kennedy

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Location
Miami Fla.
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60 yr old tool twisting electrician
I started an install today that requires adding two more 2" EMT runs to an existing rack of four. Each EMT contains or will contain three 3/0 and the EMT is the EGC.

These are/will be parallel conductors.

The the project PM looks up at the first 150' run and says I can't use set screw fittings, he just got a pdf spec requiring compression.(after contract is signed???)

I tell him I have to match existing as per this:

310.4 Conductors in Parallel.
(C) Separate Cables or Raceways. Where run in separate cables or raceways, the cables or raceways with conductors shall have the same number of conductors and shall have the same electrical characteristics.
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So if I have 4 raceways existing with set screw fittings and add 2 with compression fitting, do my raceways have the same characteristics???
 
chris kennedy said:
So if I have 4 raceways existing with set screw fittings and add 2 with compression fitting, do my raceways have the same characteristics???
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IMO, Yes they do. I believe they are talking about the materials that are used
 
chris kennedy said:
I started an install today that requires adding two more 2" EMT runs to an existing rack of four. Each EMT contains or will contain three 3/0 and the EMT is the EGC.

These are/will be parallel conductors.

The the project PM looks up at the first 150' run and says I can't use set screw fittings, he just got a pdf spec requiring compression.(after contract is signed???)

I tell him I have to match existing as per this:


So if I have 4 raceways existing with set screw fittings and add 2 with compression fitting, do my raceways have the same characteristics???
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I say the "characteristics" would be the same. How far are "You" or the inspector gonna take the word Characteristics? I mean are you gonna loosen a screw on the existing set screw coupling to make sure you know the exact amount of turns it was tighten or weigh each piece of EMT to make sure it's exactly the same(ok thats over board :) ) so that "THE" characteristics are the same? I don't think so. EMT, ran parallel as close as possible should be fine. JMO.
 
iwire said:
I agree with you Chris, it says what it says.
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So does that mean it must have the same number of bends, same number of couplings and connectors? I'll assume # of straps is not important:grin:
 
Dennis Alwon said:
So does that mean it must have the same number of bends, same number of couplings and connectors? I'll assume # of straps is not important:grin:
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Yes to all of the above. Any of the above changes can change the impedance of the conduit run.

Also the code requires what ever spacing you have chosen to be maintained.
 
I can't see why there would be a difference between the two couplings. Are they are worried wether one is a bettter fitting to provide a ground path? There is no spec on it that I know of and there are an awfull lot of differing opinions on this forum on the subject.
 
iwire said:
That is not relevant, the words say 'the same'.
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nothing is ever the same,close but not exact.The metal itself is not likely to be the same.The other fittings are not likely to even match each other in tightness.Ithink this spec is going too far for no reason.My opinion only
 
iwire said:
That is not relevant, the words say 'the same'.
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The words say that the conductors must be the same length too and that is not possible so the words prohibit the use of parallel conductors. This is a code section that needs a lot a work.
 
iwire said:
Chevy check this out, it is posted in the front of the NEC forum. #5
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Ok but if you gonna post a message(quote) with examples of how people are breaking the rules then you shouldn't delete a message when one doesn't comply with that. The message that was deleted didn't insert symbols to imitate letters like your example shows. The symbols in question could have been a million different things. Not our fault you guys bring the construction mind set to the forum. So if I say this *(^$, you are gonna think its any four letter cuss word....great. So you "Moderators" are like an AHJ and the way "YOU" interpret things is the way it goes. We are all in trouble. :)
 
don_resqcapt19 said:
The words say that the conductors must be the same length too and that is not possible so the words prohibit the use of parallel conductors. This is a code section that needs a lot a work.
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I agree with you on both points 100%.
 
chevyx92 said:
So you "Moderators" are like an AHJ and the way "YOU" interpret things is the way it goes. We are all in trouble. :)
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Well, we may all be in trouble. :D

Roger
 
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