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Old 08-17-2013, 01:32 AM   #1
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NM cable in PVC electrical conduit


I installed a 1.5" diameter 10' piece of the gray PVC electrical conduit on the side of a floor joist in the basement.

I plan on running four 12/2 NM cables through it. Is this OK? Basically using it as a raceway. Both ends are open.

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Last edited by tommyxv; 08-17-2013 at 09:32 AM. Reason: fixed diameter size
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Old 08-17-2013, 02:02 AM   #2
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NM cable in PVC electrical conduit


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Originally Posted by tommyxv View Post
I installed a 2" diameter 10' piece of the gray PVC electrical conduit on the side of a floor joist in the basement.

I plan on running four 12/2 NM cables through it. Is this OK? Basically using it as a raceway. Both ends are open.
I belive it can be ok but the gotcha is the derating due you are bundling them so the derating factor do kick in so you may loose some of the amp capaity rating.

I have to take a look at the NEC code for excat numbers due I am used on French side but for sure you will loose of them unless you put a second one inch PVC conduits then you can able use full rating of the NM cable.

Merci,
marc

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Old 08-17-2013, 02:39 AM   #3
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NM cable in PVC electrical conduit


Here the update I did check the Art 310.15 (B) (3).(a)

4 to 6 CCC's = 80%
7 to 9 CCC's = 70%
10 to 20 CCC's = 50%


Note : the ground ( bare ou green do not count as CCC's at all ) conductors are not included on this one.

So 4 X 2 NM CCC's = 8 which therfore it will be at 70% rating and my chart for #12 NM at 90C is 25 or 30 amps depending on the chart table it being used ( this is used for derating ONLY .,,, )

So 25 amp X 70% = 17.5 amps.

Or 30 amps X 70% = 21 amps.

NOTE: this is a derated verison so most NM-B cables gernally will have 90C rated conductors but if you have older cable like plain jane NM then it will be restricted to 60C rating so that will pretty much seal it.

But the cable itself is rated 60C for ampacity purpose.

As long it is not hevey loaded you are allright with it.

Merci,
Marc
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Last edited by frenchelectrican; 08-17-2013 at 06:21 AM. Reason: add correction on the error on NEC part ( got it crossed with French codes )
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Old 08-17-2013, 09:00 AM   #4
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NM cable in PVC electrical conduit


Quote:
Originally Posted by tommyxv View Post
I installed a 2" diameter 10' piece of the gray PVC electrical conduit on the side of a floor joist in the basement.

I plan on running four 12/2 NM cables through it. Is this OK? Basically using it as a raceway. Both ends are open.
Yes, that is acceptable. You might want to consider running four 12-3 cables to get twice as many circuits, the neutrals would not count as current carrying conductors in that application.

Last edited by stickboy1375; 08-17-2013 at 09:03 AM.
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Old 08-17-2013, 09:19 AM   #5
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NM cable in PVC electrical conduit


Thank you for all that info. It is all brand new 90C NM cable.

It's actually 1 1/2" conduit.

3 cables are 12/3 for 3 way switches (same circuit)
2 cables are 12/2 for wall receptacles (2 circuits)




Normally I would staple the NM to the side of the joist, but these runs were going over duct work and it was much easier to run it this way. One end up and to 5' of this conduit will be enclosed in a ceiling if that matters.
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Old 08-17-2013, 09:20 AM   #6
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NM cable in PVC electrical conduit


I wouldn't lose any sleep over that installation.
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Old 08-17-2013, 09:47 AM   #7
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NM cable in PVC electrical conduit


My question is WHY do this at all??? Cable stackers would look just as good, probably be easier, and also easier to add cables later.

Does it pass though a barrier or wall somehow?
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Old 08-17-2013, 09:48 AM   #8
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You might want to consider running four 12-3 cables to get twice as many circuits, the neutrals would not count as current carrying conductors in that application.
Thing is if this is for home runs then AFCI would likely be required, and we know how easy 2-pole AFCIs are to get, and how cheap they are.
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Old 08-17-2013, 10:13 AM   #9
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NM cable in PVC electrical conduit


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Originally Posted by Speedy Petey View Post
My question is WHY do this at all??? Cable stackers would look just as good, probably be easier, and also easier to add cables later.

Does it pass though a barrier or wall somehow?
No, it just goes over duct work (two trunk lines) and the main steel I beam. Getting into your arms, tools, etc in that area to fasten cable or those stackers would be very difficult. Plus I already had the conduit on hand. As long as it's not against code or a fire hazzard, I can deal with it.

Last edited by tommyxv; 08-17-2013 at 10:15 AM.
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Old 08-17-2013, 11:02 AM   #10
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NM cable in PVC electrical conduit


Quote:
Originally Posted by tommyxv
I installed a 1.5" diameter 10' piece of the gray PVC electrical conduit on the side of a floor joist in the basement.

I plan on running four 12/2 NM cables through it. Is this OK? Basically using it as a raceway. Both ends are open.
It is not a raceway, it is a sleeve. No more than four 12/2,s are fine.
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Old 08-17-2013, 11:11 AM   #11
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NM cable in PVC electrical conduit


Thanks for the replies. I will continue to route those cables to thier destinations then. I was waiting to see the responses in case I had to remove the conduit.
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Old 08-17-2013, 04:00 PM   #12
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NM cable in PVC electrical conduit


Quote:
Originally Posted by Speedy Petey View Post
Thing is if this is for home runs then AFCI would likely be required, and we know how easy 2-pole AFCIs are to get, and how cheap they are.

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Old 08-17-2013, 04:29 PM   #13
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NM cable in PVC electrical conduit


Why would I need an AFCI?
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Old 08-17-2013, 05:21 PM   #14
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NM cable in PVC electrical conduit


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Why would I need an AFCI?
Depends on what code cycle you are on and what areas the circuits are for.
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Old 08-17-2013, 07:47 PM   #15
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NM cable in PVC electrical conduit


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And these meet code how??

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