Wires in conduit

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  #1  
Old 01-12-11, 09:36 PM
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Wires in conduit

I am helping a friend who is starting back up on an existing project. He has 8 pairs of white and black wires run through about 20' of conduit. What is the easiest way to match up the white and blacks for each circuit? He didn't mark any of them.
 
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  #2  
Old 01-12-11, 10:07 PM
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Assuming all the same gauge twist a black and white together on one end and check for continuity on the other.
 
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Old 01-13-11, 06:28 AM
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Rays way is the most foolproof. Sometimes you can also tug on one end while someone watches the other end of the conduit.

Did your friend consider ther derating issues before installing that many conductors in the conduit?
 
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Old 01-13-11, 11:15 AM
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8 Pairs of wires? With 16 wires I hope he ran a good sized pipe.
 
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Old 01-13-11, 07:02 PM
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Originally Posted by palmcoast View Post
I am helping a friend who is starting back up on an existing project. He has 8 pairs of white and black wires run through about 20' of conduit. What is the easiest way to match up the white and blacks for each circuit? He didn't mark any of them.
If the white wires are all neutrals, it doesn't matter much which white wire you pair with a black wire as they all terminate in the neutral bus anyway. For only 20 feet of conduit, I like the tug method pcboss mentioned.
 
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Old 01-13-11, 07:50 PM
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Originally Posted by CasualJoe View Post
If the white wires are all neutrals, it doesn't matter much which white wire you pair with a black wire as they all terminate in the neutral bus anyway. For only 20 feet of conduit, I like the tug method pcboss mentioned.
Actually it does matter. Code requires circuits in conduit to be grouped.
 
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Old 01-13-11, 08:00 PM
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Originally Posted by Tolyn Ironhand View Post
Actually it does matter. Code requires circuits in conduit to be grouped.
But, aren't all 16 wires in the same conduit?
 
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Old 01-14-11, 11:35 PM
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My miistake, it is actually a total of 4 white, 4 black and 1 ground in a 3/4" conduit.
 
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Old 01-15-11, 08:50 AM
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Originally Posted by CasualJoe View Post
But, aren't all 16 wires in the same conduit?
Yes, they are. I can't recall the code reference but I believe 2008 cod requires circuits in the same pipe to be grouped together. (IE: hot with it's neutral or hots together.)

My miistake, it is actually a total of 4 white, 4 black and 1 ground in a 3/4" conduit.
Your good then.
 
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Old 01-15-11, 11:54 AM
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I am not trying to argue, but looking for clarification. Now we are at 4 white conductors, 4 black conductors and 1 green grounding conductor in a single 3/4" conduit. At the panel, each white terminates on the neutral bar, each black terminates at a single pole breaker and the grounding conductor terminate at the ground bar (my assumption). Assuming the other end is a junction box and all conductors are the same size, what difference does it make which white conductor is paired with a specific black conductor? OR....is the code reference requiring that each pair at each end by ty wrapped together to form a group? I have a 2008 Analysis of Changes book, I'll see if I can find anything on this.
 
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Old 01-15-11, 02:20 PM
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Black and White Pairs

Would matching pairs be necessary when using arc fault breakers? I am thinking yes. What do the pros think?
 
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Old 01-15-11, 05:44 PM
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Originally Posted by Wirepuller38 View Post
Would matching pairs be necessary when using arc fault breakers? I am thinking yes. What do the pros think?
I'd say yes to that question too because each neutral conductor has to terminate on the same breaker as the hot conductor it is the match too. But what we were discussing is different, all the neutral conductors go to the neutral bar.
 
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Old 01-15-11, 06:06 PM
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Originally Posted by Tolyn Ironhand View Post
Yes, they are. I can't recall the code reference but I believe 2008 cod requires circuits in the same pipe to be grouped together. (IE: hot with it's neutral or hots together.)



Your good then.
300.20
(A) Conductors Grouped Together. Where conductors
carrying alternating current are installed in ferrous metal
enclosures or ferrous metal raceways, they shall be arranged
so as to avoid heating the surrounding ferrous metal
by induction. To accomplish this, all phase conductors and,
where used, the grounded conductor and all equipment
grounding conductors shall be grouped together.

Exception No. 1: Equipment grounding conductors for
certain existing installations shall be permitted to be installed
separate from their associated circuit conductors
where run in accordance with the provisions of 250.130(C).

Exception No. 2: A single conductor shall be permitted to
be installed in a ferromagnetic enclosure and used for skineffect
heating in accordance with the provisions of 426.42
and 427.47.
 
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Old 01-15-11, 07:11 PM
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Originally Posted by Danny7633 View Post
300.20
(A) Conductors Grouped Together. Where conductors
carrying alternating current are installed in ferrous metal
enclosures or ferrous metal raceways, they shall be arranged
so as to avoid heating the surrounding ferrous metal
by induction. To accomplish this, all phase conductors and,
where used, the grounded conductor and all equipment
grounding conductors shall be grouped together.

Exception No. 1: Equipment grounding conductors for
certain existing installations shall be permitted to be installed
separate from their associated circuit conductors
where run in accordance with the provisions of 250.130(C).

Exception No. 2: A single conductor shall be permitted to
be installed in a ferromagnetic enclosure and used for skineffect
heating in accordance with the provisions of 426.42
and 427.47.
Thanks, Danny7633. In the example we were discussing there are 4 white conductors, 4 black conductors and 1 grounding conductor in the same pipe (all the same size I believe). Danny, in your opinion, how would those conductors be properly grouped to comply with provisions of NEC 300.20?
 
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Old 01-15-11, 08:20 PM
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If you wanted to you can pair the branch by fastening the ungrounded to the grounded conductor prior to pulling the wire by a means which would not damage the conductors (tape)

I believe their intent is to make sure the return path is in the same conduit to cancel inductive heating, I believe this to comply with grouping.
 
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Old 01-16-11, 08:25 AM
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Originally Posted by Danny7633 View Post
300.20
(A) Conductors Grouped Together. Where conductors
carrying alternating current are installed in ferrous metal
enclosures or ferrous metal raceways, they shall be arranged
so as to avoid heating the surrounding ferrous metal
by induction. To accomplish this, all phase conductors and,
where used, the grounded conductor and all equipment
grounding conductors shall be grouped together.

Exception No. 1: Equipment grounding conductors for
certain existing installations shall be permitted to be installed
separate from their associated circuit conductors
where run in accordance with the provisions of 250.130(C).

Exception No. 2: A single conductor shall be permitted to
be installed in a ferromagnetic enclosure and used for skineffect
heating in accordance with the provisions of 426.42
and 427.47.
I always took this to mean that A, B, C and the neutrals all had to be in the same raceway. Not A in one conduit, B in another etc.
 
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Old 01-16-11, 09:54 AM
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Originally Posted by Danny7633 View Post
If you wanted to you can pair the branch by fastening the ungrounded to the grounded conductor prior to pulling the wire by a means which would not damage the conductors (tape)

I believe their intent is to make sure the return path is in the same conduit to cancel inductive heating, I believe this to comply with grouping.
I would agree with that. In my opinion, the key phrase here is "If you wanted to". In reality, the spools of wire would be on a rack and the wire is pulled from them making it impractical to individually tape together the conductors in each individual circuit. I am open to any other interpretations. But, in the example, the conduit is only 20 feet long so it would be possible to pull four lengths of white off the spool and four lengths of black off the spool and tape them together into groups before pulling the wire into the conduit.
 
  #18  
Old 01-16-11, 04:23 PM
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Neutrals

all the neutral conductors go to the neutral bar.
This fact is not stated by the OP. I believe it is an assumption.
 
  #19  
Old 01-16-11, 05:12 PM
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I paired them and checked the continuity to match them up. Two circuits were for bedroom ARC fault breakers and two were lighting circuits. Thank you very much for the help.
 
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Old 01-17-11, 06:16 PM
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Originally Posted by Wirepuller38 View Post
This fact is not stated by the OP. I believe it is an assumption.
True, it was an assumption because of no mention of either a GFCI or AFCI in the OP. Where would you have assumed them to go, given the information provided? Now, from the latest post we see that two circuits were indeed AFCI circuits and that two of the white conductors would have to be paired with black conductors.
 
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