Underground wiring

[sgray]

If I am running wire to a remote garage through schedule 30 PVC, (completely sealed from house to garage) Do i still need to use UF in the PVC or can I run NM?

 

[bphgravity]

Re: Underground wiring

I assume you mean either schedule 40 or schedule 80 pvc.

 

[sandsnow]

Re: Underground wiring

You cannot use Type UF in this instance. It is not listed for use in conduit. The installation you describe requires individual conductors.
Larry LeVoir
City of Irvine,CA

 

[bphgravity]

Re: Underground wiring

I just checked the UL "YDUX.GuideInfo" for UF cable listing and do not see where UF is restricted from installation in conduit.

If you are commenting on the NEC's allowance of UF in conduit, it has been generally agreed that it is not the intent of the code to restrict the use of UF or NM cable from being installed in a raceway

 

[sandsnow]

Re: Underground wiring

I was mistaken, the guide does not restrict it. There needs to be one of those little faces with a foot in it's mouth. I would be curious if UL has investigated it for use in conduit.
If there has been a Formal Interpretation on UF or NM in conduit I would be very interested in seeing it.
How do you calculate wire fill for UF or MN in conduit?
We have always allowed NM or UF to be sleeved in conduit. Generally if the conduit exceeds 10 feet in length it is no longer a sleeve.
From a practical standpoint why would you want to fight it? Single conductors are so much easier to install.

 

[don_resqcapt19]

Re: Underground wiring

Bryan,

If you are commenting on the NEC's allowance of UF in conduit, it has been generally agreed that it is not the intent of the code to restrict the use of UF or NM cable from being installed in a raceway

I don't agree with that statement. There are code "experts" on both sides of that issue. I agree with those experts who say that NM and UF cannot be installed in complete raceway systems.
Don

 

[ryan_618]

Re: Underground wiring

I have the privelege of sitting on the board of directors (Utah chapter IAEI) with one of the gentlemen that serves on CMP 7 (Gaylen Rogers)for the cable wiring method articles. It is his contention that these cable systems cannot be installed in a complete raceway system. There was a tentative amendment to be entertained for the 2005 NEC to allow this practice, but it fell through. Talking with Gaylen, he leads me to beleive that it will be addressed in the 2008 version.

I agree with Don, who is, in my opinion, an expert himself, whether he will admit it or not.

 

[bphgravity]

Re: Underground wiring

My record has been clear on this issue, however, after all considerations, the arguement for not installing UF or NM in a raceway is weak at best. The scope of the NEC is in no way violated by the use of these cabling systems in this method. I believe that from a code purist point of view there is no specific allowance, but a reasonable code user sees that its absolute restriction is not there either.

 

[don_resqcapt19]

Re: Underground wiring

Bryan,
I agree that in most cases the code does not have to provide a specific permission so that something can be done, but it is my opinion that this is one of the rare cases where a specific permission in the cable article is required. I say this only because, the wording in the xxx.22 sections of the raceway articles requires this specific permission.

Cables shall be permitted to be installed where such use is permitted by the respective cable articles.

Don

PS, Ryan, I'm not an expert, just a student.

 

[ryan_618]

Re: Underground wiring

Originally posted by bphgravity:
The scope of the NEC is in no way violated by the use of these cabling systems in this method.

Bryan I agree with your statement, and so does the NFPA, which is why the amendment was being considered. From my understanding, the reason it is not going to be in the 2005 is that the CMP simply ran out of time. By the way, it is also my understanding the cable wiring methods were supposed to be permitted for this use, but the 2 CMP's for cables and raceways simply didn't communicate well enough between them.

 

[sandsnow]

Re: Underground wiring

I answered my own question , unfortunately it does not support my opinion.
Notes 5 and 9 to Table 1 Chapter nine tell you how to size conduit when multi-conductor cables are used.

 

[brentp]

Re: Underground wiring

What would be the reason as to why we cannot install uf in underground pvc?

[ May 05, 2004, 06:58 PM: Message edited by: brentp ]

 

[roger]

Re: Underground wiring

Brent, with all due respect to those who think there is a problem or some subliminal wording that prohibits this, I'll counter and say IMO there is nothing prohibiting or implying this is a code violation.

If there is someone on a CMP that is trying to say this was their intent, then all we can do is hope they will expand their literary skills before they write their next article.

Roger

 

[pierre]

Re: Underground wiring

Don
I concur with Ryan - you are an expert... 'student'
Roger I am very much in support of your last sentence of your last post. I will say that it is not easy to write code that will be semantically and gramatically correct - especially when a forum like this and the others exist, where so many can make comments and nitpick through the verbage.

I will say that part of the thought process of not permitting the cable installation in a raceway is the heat dissapation which is so very important - especially over a period of time.

Pierre

 

[brentp]

Re: Underground wiring

Heat dissapation has to do with EVERY conductor. Why not do a little more derating if I want to put uf in a raceway? Why just not allow it?

 

[bphgravity]

Re: Underground wiring

If heat dissipation is the issue, then why is cable Type FC, MV, MC, and TC allowed? Again, the codes inconsistency tends to show specific permitted use of NM or UF in a raceway is nothing more than an error.

 

[a.wayne3@verizon.net]

Re: Underground wiring

I have to side with bryan. 300 5 d 5 allows cable raceways to be installed under ground ( i have posted this thread before .
Nm is allowed.

 

[drg]

Re: Underground wiring

Nm cannot be ran underground , even if inside RNC this would be considered a wet location........ and NM is not permitted according to 334.12(a) (10) (d)correct???

[ May 06, 2004, 10:08 PM: Message edited by: drg ]

 

[bennie]

Re: Underground wiring

I don't understand what the problem or inconsistency is, this seem interesting. Please elaborate.

 

[ryan_618]

Re: Underground wiring

Originally posted by ryan_618:
Hi Bennie. The debate is this: 352.22 Says that cables may be installed in the raceway (RNC in this case) when the it is permmited by the cable article. The NM cable article (334) makes no such allowance.

So, while I agree with Bryan in that it was an error, I happen to agree with Don's perspective more, because that is what the code says, like it or not. As I noted on one of my posts, the CMP responsible for the mistake has acknowledged to me (perhaps off the record) that it was a mistake, but that doesn't change the wording of the code.

Edited to address my incoherent babbling