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Old 05-09-2012, 10:12 PM   #1
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Correct cable for 10/2 in NM conduit


I'm running several circuits from one end of the house (panel) to the other. The house is primarily CMU construction so I'm running these new circuits in a PVC conduit alongside the house. I only need 2 or 3 15/20 amp circuits and plan to use #10 from the panel through the conduit due to run length (>70ft). I'll move to #12 from the far end of the conduit to receptacles (the conduit comprises most of the distance).

My question is: what type of cable should I be using for this? I know I need THWN but I'd prefer not to end up with extra JBs and splices at each end of the conduit. If Romex was THWN it'd be perfect to cut off the sheathing for the conduit section but it isn't so that's not to code. I've seen tray cable that specifies THWN for it's conductors but have a feeling it's gonna be a real pain to cut all the insulation away from 60ft of it. I figure something probably exists for this purpose and I just don't know what it's called.

Thanks.

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Old 05-09-2012, 10:18 PM   #2
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Correct cable for 10/2 in NM conduit


Is this conduit open ended, as in a chase or is it terminated at either or both ends in a box? Cable can't be run in conduit but for a few exceptions, such as using the conduit as a chase from one area to another, or between floors. Short lengths of conduit can be used for protection for cable, such as in an area where the cable could be damaged....garage, basement....etc. And for my information...what is "CMU"?

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Old 05-09-2012, 10:21 PM   #3
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Correct cable for 10/2 in NM conduit


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Originally Posted by greg619 View Post
I'm running several circuits from one end of the house (panel) to the other. The house is primarily CMU construction so I'm running these new circuits in a PVC conduit alongside the house. I only need 2 or 3 15/20 amp circuits and plan to use #10 from the panel through the conduit due to run length (>70ft). I'll move to #12 from the far end of the conduit to receptacles (the conduit comprises most of the distance).

My question is: what type of cable should I be using for this? I know I need THWN but I'd prefer not to end up with extra JBs and splices at each end of the conduit. If Romex was THWN it'd be perfect to cut off the sheathing for the conduit section but it isn't so that's not to code. I've seen tray cable that specifies THWN for it's conductors but have a feeling it's gonna be a real pain to cut all the insulation away from 60ft of it. I figure something probably exists for this purpose and I just don't know what it's called.

Thanks.
Romex is not permitted in a wet location regardless of whether it is stripped or not. THW or THWN is acceptable for what you want to do.
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Old 05-09-2012, 10:21 PM   #4
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Correct cable for 10/2 in NM conduit


THWN wire or THHN wire dual rated as THWN. But you will need a breaker panel at the other end of the conduit if you have the 10 gauge wire protected with a 30 amp breaker so you can protect each set of conductors with the proper amperage.
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Old 05-09-2012, 10:27 PM   #5
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Correct cable for 10/2 in NM conduit


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Originally Posted by Missouri Bound View Post
Is this conduit open ended, as in a chase or is it terminated at either or both ends in a box? Cable can't be run in conduit but for a few exceptions, such as using the conduit as a chase from one area to another, or between floors. Short lengths of conduit can be used for protection for cable, such as in an area where the cable could be damaged....garage, basement....etc. And for my information...what is "CMU"?
CMU = Concrete Masonry Unit
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Old 05-09-2012, 10:40 PM   #6
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Correct cable for 10/2 in NM conduit


Missouri Bound: Yes the conduit is open ended. Both ends terminate inside / under the house. If I have to splice individual THWN to romex at each location then I will do so (inside of boxes). CMU: concrete masonry unit (ie. concrete block)

electures: My description actually said just that. My question is: is there a bundled cable that would allow me to strip off said section and install without the need for JBs and splices at each end? (I realize I could run conduit or individual THWN from the panel to the conduit but I'm trying to avoid that.)

rrolleston: I was originally going to put a panel at the other end but only have 3 circuits so am considering just running the 6 conductors necessary. It would be much cleaner if I could find an appropriate cable bundle to use for each of the 3 circuits which is why I'm asking. I know I "can" just put the 6 THWN conductors (plus grounds) with appropriate termination boxes but I'm trying avoid that on the panel end.

Diagram to clarify:

______ -------conduit (THWN)-----romex to receptacles
--------| ==|===========|===>
Panel--| ==|===========|===>
--------|==|===========|===>
---------- Jct A -------------- Jct B

At Jct B I plan to have a box and connect my #10 conductors from the conduit to #12 to feed my receptacles. At Jct A, however, I'd like to avoid the extra box and just run cable from the panel into the conduit. If there is a tray cable (or other) that is typically used for this that I can simply strip the sheathing off of for the conduit section that would be stellar. Or, if there is a bundle that is ok to run in wet conduit locations that would be great too. rroleston: you may have been alluding to this but is there a name for the bundled THWN (or dual rated THHN)?

Thanks.
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Old 05-09-2012, 10:52 PM   #7
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Correct cable for 10/2 in NM conduit


Well.......here's my take on this. If you used the pvc as protection for part of the cable run I don't see a problem. But when you make a splice you need a junction box, and then a cover. Your "under the house" location is also a wet location, so you can't use romex, you must use UF. Now if you terminate the conduit at both ends with boxes you can't use a cable, you would need thwn. I can't think of another way to explain it, does that help?
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Old 05-09-2012, 10:59 PM   #8
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Correct cable for 10/2 in NM conduit


There is no code that says you cannot pull NM(Never allowed in wet locations, even in conduit) or UF Cable in conduit(other than a waste or labor), but you must have a large enough conduit to meet wire fill, which for cables is usually fairly large
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Old 05-09-2012, 11:26 PM   #9
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Correct cable for 10/2 in NM conduit


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There is no code that says you cannot pull NM(Never allowed in wet locations, even in conduit) or UF Cable in conduit(other than a waste or labor), but you must have a large enough conduit to meet wire fill, which for cables is usually fairly large
I stand corrected.
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Old 05-09-2012, 11:52 PM   #10
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Correct cable for 10/2 in NM conduit


Fill isn't an issue I ran 2 1/2" conduit "just in case" I wanted to pull for a subpanel.

Sounds like I'll be stuck with boxes at each end. Thanks for clearing this up. And thanks for the tip on UF under the house (from what I've seen, it seems like this one gets broken a lot.)
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Old 05-09-2012, 11:55 PM   #11
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Correct cable for 10/2 in NM conduit


If you are going to put boxes at each end of the conduit you may as well pull individual wires. You can greatly reduce the size of the conduit by pulling THWN rather than UF.
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Old 05-10-2012, 12:05 AM   #12
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Correct cable for 10/2 in NM conduit


UF cable meets your requirements, but you're not going to have fun pulling two 10/2 UF cables through any size conduit. The most normal solution to this would be to run the conduit from the panel all the way to a box on the inside of the house at the other end, and pull THWN. Then transition to NM cable at the box.
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Old 05-10-2012, 12:11 AM   #13
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Correct cable for 10/2 in NM conduit


The conduit is already run (had a trench for plumbing dug and decided to plan ahead rare, I know). Individual THWN wins at this point. If only I could put a subpanel under the house... pain in the butt to reset breakers but would save me some coin on the wire.

Thanks guys. Have a good one.
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Old 05-10-2012, 12:12 AM   #14
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Correct cable for 10/2 in NM conduit


missed the part where you already ran the 2 1/2"
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Old 05-10-2012, 09:16 AM   #15
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Correct cable for 10/2 in NM conduit


Quote:
Originally Posted by greg619 View Post
Missouri Bound: Yes the conduit is open ended. Both ends terminate inside / under the house. If I have to splice individual THWN to romex at each location then I will do so (inside of boxes). CMU: concrete masonry unit (ie. concrete block)

electures: My description actually said just that. My question is: is there a bundled cable that would allow me to strip off said section and install without the need for JBs and splices at each end? (I realize I could run conduit or individual THWN from the panel to the conduit but I'm trying to avoid that.)

rrolleston: I was originally going to put a panel at the other end but only have 3 circuits so am considering just running the 6 conductors necessary. It would be much cleaner if I could find an appropriate cable bundle to use for each of the 3 circuits which is why I'm asking. I know I "can" just put the 6 THWN conductors (plus grounds) with appropriate termination boxes but I'm trying avoid that on the panel end.

Diagram to clarify:

______ -------conduit (THWN)-----romex to receptacles
--------| ==|===========|===>
Panel--| ==|===========|===>
--------|==|===========|===>
---------- Jct A -------------- Jct B

At Jct B I plan to have a box and connect my #10 conductors from the conduit to #12 to feed my receptacles. At Jct A, however, I'd like to avoid the extra box and just run cable from the panel into the conduit. If there is a tray cable (or other) that is typically used for this that I can simply strip the sheathing off of for the conduit section that would be stellar. Or, if there is a bundle that is ok to run in wet conduit locations that would be great too. rroleston: you may have been alluding to this but is there a name for the bundled THWN (or dual rated THHN)?

Thanks.
To my knowledge, no. What ever cable is used, it has to be rated for a wet location. Your diagram will work though. Panel -> JB -> conduit (with individual conductors) -> JB -> romex -> boxes. Can you run the cabling inside the dwelling, or put install a subpanel?

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Last edited by electures; 05-10-2012 at 09:20 AM.
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