NM B in Conduit?

[nine4gmc]

Can I run a circuit from my sub panel in the 30x30 unattached building using NM B 12-2 for lighting in 1/2" conduit? My walls are bare metal, existing wiring is separate wires in conduit from the sub panel to junction boxes at the ceiling and there are six 8' long T12s hanging from the ceiling with 14-2 NM B drooped over to the junction boxes. All receptacles are conduit with separate wires. I want to add another light circuit across the center of my building on a separate switch for smaller lights when I don't need the over heads on. I have a **** load of new 12-2 NM B reason I ask. I would also like to run a pair of NM B to the other side of my shop for a 240v and two 120v circuits on that wall if it's allowed.

Thanks in advance.

 

[alfredeneuman]

1ea - 12/2 NM requires 3/4" conduit. It's measured at it's greatest dimension, and at 53% fill (for 1 wire in conduit) is too large to fit in a 1/2".

2ea - 12/2 would require 1" conduit. (@31% fill)

That's the price you pay when you run NM in conduit

 

[nine4gmc]

So what about yanking the jacket off the NM B? Is that no bueno?

 

[Charles (in GA)]

The wires inside are not marked, only the jacket, so they cannot be used individually.

Charles

 

[MoonRise]

So what about yanking the jacket off the NM B? Is that no bueno?

No bueno.

If you want to run individual wires in conduit, get some THHN (or similar).

NM-B is cable, and is to be used as-is with the outer jacket protecting the inner conductors. Can't strip off the outer jacket and try and use the inner 'wires' stand-alone fashion. NG. Or en espanol, NB.

 

[nine4gmc]

Gotcha and my last(I think) question, the lights are hanging and there is a NM B 14/2 drooped from them to the junction boxes on the building center frame. Is that normal? The inspector passed it and I didn't think to mention but since we are on the topic somewhat, anyone?

 

[rockwithjason]

if they are more than 8ft above the floor you are ok

 

[nine4gmc]

Yes they are, thanks for all the help guys!

 

[nine4gmc]

OK I managed to think of one more stupid question. Can I pull a separate single 12ga red wire through 3/4" conduit along with one 12-2 NM B to have 4 wires and make my 240v and 120v outlets on the other wall?

 

[wyliesdiesels]

OK I managed to think of one more stupid question. Can I pull a separate single 12ga red wire through 3/4" conduit along with one 12-2 NM B to have 4 wires and make my 240v and 120v outlets on the other wall?

First off u cant use wires in separate cables to make up a circuit.

And u wouldnt have enough wires doing that- only 3.

Your making this harder than it has to be.

Just use some THWN and be done with it.

 

[nine4gmc]

Sorry to make this hard for you Wylie, I was just trying to work with what I had on hand. I now see that the NM B will not work for my intended purposes so I will look for another route.

Will THHN work? I just scored all this for $20 off CL minutes ago. Those were 500' rolls so there should be enough wire there to do what I need if it will work.

 

[Falcon67]

FWIW - I have put a lot of NM in conduit and it's just easier using 3/4", without regard to fill etc. You can do it in 1/2 but it's a pain to thread even a straight run, let alone any bends.

 

[wyliesdiesels]

Sorry to make this hard for you Wylie, I was just trying to work with what I had on hand. I now see that the NM B will not work for my intended purposes so I will look for another route.

Will THHN work? I just scored all this for $20 off CL minutes ago. Those were 500' rolls so there should be enough wire there to do what I need if it will work.

Not making it hard on me...I could care less. Just trying to help u...

What gauge is the wire?

Yes THHN is what u need!

Thats a total score for $20! Nice find!

 

[alfredeneuman]

Wow!!

$200+worth for wire for $20.

It looks like 5 rolls of #12 and almost a full roll of #10

 

[nine4gmc]

Not making it hard on me...I could care less. Just trying to help u...

What gauge is the wire?

Yes THHN is what u need!

Thats a total score for $20! Nice find!

Thanks Wylie

Wow!!

$200+worth for wire for $20.

It looks like 5 rolls of #12 and almost a full roll of #10

That's exactly what it is, the ad mentioned that it sells for about $55 per roll new and all he wanted was $20 for the entire lot. He also gave me two new packs of 12ga wire with about 50' lengths in each but it was soft multi strand wire like for automotive use. I gotta get with my scrap guy this week, he has a bunch of new/like new conduit holding for me then I will run my circuits.

Finally

 

[wyliesdiesels]

Almost seems like it was stolen.

Why so low?

 

[nine4gmc]

He was an older guy(I'm 42) looked/seemed honest, he said he got it for a job a long time ago and that was leftovers and he no longer did that type of work, just cleaning out his shed. He also mentioned he ran this same wire direct burial to his shed and powers a light and a table saw and other small tools with it.

When I first read the ad, I was getting excited and thinking what to offer for the whole lot(thinking he wanted $20 per roll) but I read it again before contacting him and then he confirmed when we spoke. He kept mentioning I could scrap it for more but I assured him it would be put to use. I told him the timing could not have been more perfect!!!

 

[nadogail]

He may have run NM or NM-B underground.

It maybe has not failed him yet, that still does not make NM or NM-B approved for the purpose.

And wrong, even if it seems to work, is still wrong.

Your choices are: Good, Fast, and Cheap. You may pick only two of the three.

 

[nine4gmc]

Ok now that I have the correct wire, the THHN 12ga, how many can I run in 1/2" conduit? Can I run the 4 wires needed for a 240v circuit or would it be better to go with 3/4"? Do I even need 4 wires or can I ground the outlets to the junction boxes and only run 3 wires?
Sorry for all the questions and thank you for the answers.

 

[wyliesdiesels]

He was an older guy(I'm 42) looked/seemed honest, he said he got it for a job a long time ago and that was leftovers and he no longer did that type of work, just cleaning out his shed. He also mentioned he ran this same wire direct burial to his shed and powers a light and a table saw and other small tools with it.

When I first read the ad, I was getting excited and thinking what to offer for the whole lot(thinking he wanted $20 per roll) but I read it again before contacting him and then he confirmed when we spoke. He kept mentioning I could scrap it for more but I assured him it would be put to use. I told him the timing could not have been more perfect!!!

*facepalm* That wire isnt rated for direct bury as im sure u know....

Ok now that I have the correct wire, the THHN 12ga, how many can I run in 1/2" conduit? Can I run the 4 wires needed for a 240v circuit or would it be better to go with 3/4"? Do I even need 4 wires or can I ground the outlets to the junction boxes and only run 3 wires?
Sorry for all the questions and thank you for the answers.

I would do 3/4" at least.

And u dont need a ground wire if youre using EMT or any type of metal conduit except FMC/greenfield...

U dont need to pig tail a ground IF the outlets are self grounding....but the outlets you will be using most likely arent self grounding...so just do the pig tail to the box.

 

[nine4gmc]

*facepalm* That wire isnt rated for direct bury as im sure u know....



I would do 3/4" at least.

And u dont need a ground wire if youre using EMT or any type of metal conduit except FMC/greenfield...

U dont need to pig tail a ground IF the outlets are self grounding....but the outlets you will be using most likely arent self grounding...so just do the pig tail to the box.

I was pretty sure that wire was not made for direct burial. I mentioned my conduit issue with the NM B and he said he didn't even use conduit in his shed.

Reason I asked about the 1/2" conduit, I just picked up 11 sticks from my scrap guy for free, well sorta, I gave him 20lbs of scrap metal for it so it was more of a trade but it cost me nothing. If I can run two hots and a neutral in that 1/2" and just ground the outlets to their boxes, that's what I will do. The boxes, conduit and connectors are all metal.

Thank you guys for all the help, I know just enough about residential wiring to get me in trouble. I mean, I could definitely get it to work but it would not be up to any codes unless it was an accident...

 

[wyliesdiesels]

Yes 3 #12s will be fine in 1/2".

And for your future reference, u can view or print these charts:

http://sparkyjohn.com/pipefill/pipefill.pdf

 

[nine4gmc]

Thanks Wylie, I googled it the following day and saw I could run 9 in there but don't need that many nor know how anyone could actually pull 9 though a 1/2 conduit but glad to know it can be done. Thanks Again for all your help!

 

[pattenp]

Thanks Wylie, I googled it the following day and saw I could run 9 in there but don't need that many nor know how anyone could actually pull 9 though a 1/2 conduit but glad to know it can be done. Thanks Again for all your help!

Caveat to the 9 wires in 1/2" is that when you use more than 3 current carrying conductors you have to derate the ampcapacity.

 

[toplessHO]

*facepalm* That wire isnt rated for direct bury as im sure u know....



I would do 3/4" at least.

And u dont need a ground wire if youre using EMT or any type of metal conduit except FMC/greenfield...

U dont need to pig tail a ground IF the outlets are self grounding....but the outlets you will be using most likely arent self grounding...so just do the pig tail to the box.

please dont advertise that when life safety is an issue.
run a ground wire in all conduit metal or not and pigtail all grounds
just plain good common sense

and FYI if the flex is less than 6 ft you dont need it then either
again just good sense work habits

 

[alfredeneuman]

Caveat to the 9 wires in 1/2" is that when you use more than 3 current carrying conductors you have to derate the ampcapacity.

......but with 9 - #12s you can still use them at 20 Amps after derating.
That's the limit though.

 

[wyliesdiesels]

please dont advertise that when life safety is an issue.
run a ground wire in all conduit metal or not and pigtail all grounds
just plain good common sense

and FYI if the flex is less than 6 ft you dont need it then either
again just good sense work habits

Seriously, unless the conduit becomes separated its not an issue.

And the jackets of FMC/greenfield, MC and AC is no longer allowed to be used as an EGC...

 

[nine4gmc]

So what is the largest amperage circuit I can run with 12ga in 240v and 120v? The length of the run would be about 40' from subpanel to outlet. I'd like to run everything in one 1/2" conduit from one side of the shop to the other.

Since I have all the THHN now, running a green ground wire is no problem so I guess it would be 3 hots, 2 neutrals and a ground for a total of 6 wires in the conduit.

 

[wyliesdiesels]

20a.

Due to 240.4(d) #14, #12, and #10 are limited to 15a, 20a, and 30a respectively...

 

[nine4gmc]

Ok, and the neutral has to be the same size as the hots correct? Like, I can not run two 10ga hots and a 12ga neutral and ground for a 30a right? I would need two 10ga hots, a 10ga neutral and a 12ga ground for a four wire 240v 30a?

I have the 10ga black, I need to pick up a small roll of 10ga white I guess so i can run a 30a outlet.

 

[alfredeneuman]

The ground wire (if you decide to run one) needs to be #10 also, and is to be either green or bare. Taping it green is a violation

 

[nine4gmc]

damn, ok.

So now I am up to two 10ga hots, a 10ga neutral, a 10ga ground, a 12ga hot, neutral and ground. I'm looking at four 10ga and three 12ga now... UGH.

I may just run a 120v 20a circuit to the far side and use the existing 240v 30a outlet in the middle of the shop with an extension cord if needed(rarely).

 

[wyliesdiesels]

Remember, you can share ONE EGC between multiple circuits....it needs to be #10 in your case...

And u can omit the EGC if u really needed to....

So 3 #10s and 2 #12s...

Heres a table for sizing EGCs:

http://www.safecoelectric.com/images/resources_pdf/NEC2008 Table 250.122.pdf

 

[nine4gmc]

I'm starting to get this, bare with me.

 

[wyliesdiesels]

Youll get it.

Dont beat yourself up over it.

It takes time and a good memory...

Just the reason why an apprentiahip is usually 4-5yrs..