Is there anything wrong with running several 12/2 NM cables thru a 16 ft. PVC sleeve? I know it's OK to sleeve one cable (e.g. down a basement concrete wall). But is there a problem with running several cables in one sleeve as long as I comply with conduit fill limitations? Because of the outer jacket of NM cable, could there be extra heat trapped in the long PVC sleeve when there are other NM cables bundled in there as well? Thanks for any help with this.
Bundling & Sleeving NM Cable in PVC
- Thread starter joemly
- Start date
- Status
wireguy8169
Senior Member
- Location
- Southern Maine
Check out 334.12 (B) this may apply.
You will get different opinions on this. The only two that matter are yours (because you are liable for your work) and an inspector's (who's blessing you may or may not get).
Personally, I see nothing wrong with the installation and wouldn't think twice about it but there WILL be dissenting opinion.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
You must watch conductor fill and you need to derate.
jxofaltrds
Inspector Mike®
- Location
- Mike P. Columbus Ohio
- Occupation
- ESI, PI, RBO
300.19(c) ?????
Does apply in your installation?
Does apply in your installation?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I agree with the derating but the jury is still out on the fill for a sleeve. Is there a specific code article that requires a fill calculation? Chapter 9 Notes to the tables #(2) seems to apply.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
You are right. The derating should be all that is needed since the conduit is not meant for repulling-- why it isn't I am not sure.
wireguy8169
Senior Member
- Location
- Southern Maine
Schd 80
Schd 80
Would this need to be schedual 80 pvc? I was reading in 334.12 the means of protection and when it list PVC it specifically list Sch 80, it then goes on to say or other approved methods, so is that the kicker that kinda leaves it up to the AHJ or another section of the code?
Schd 80
Would this need to be schedual 80 pvc? I was reading in 334.12 the means of protection and when it list PVC it specifically list Sch 80, it then goes on to say or other approved methods, so is that the kicker that kinda leaves it up to the AHJ or another section of the code?
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I would say no unless the schedule 40 is subject to damage.
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
Derating is a must. Keep in mind NM is not allowed outside. So just where are you running this ?
glene77is
Senior Member
- Location
- Memphis, TN
Perhaps you are not sleeving, but nippling ?
Check 310.15
Exception No. 3: Derating factors shall not apply to conductors
in nipples having a length not exceeding 600 mm (24 in.).
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Sleeve or nipple, would it matter? Either way more than 24" derating applies, 24" of less then it doesn't unless I'm missing your point.
The sleeve is going thru a crawl space that's all closed in -- it's part of the basement of the house.
Thank you for all your replies. The reminder about derating ampacity for multiple wires in a conduit is very helpful. That pretty much answers my question, because I don't want to have to run 10/2 Romex for basic 20 amp circuits. So I'm not going to use the sleeve, and will run each 12/2 separately.
Thank you again.
- Status