Type 'W' Conductors

[iwire]

This was posted in a long running thread detached garage
and I think it deserves it's own thread.

I have said for many years, yes I have been told that I am stupid, that TW conductors installed in conduit underground is a violation of the NEC unless the conductors have the letter ?U? stamped on them.

Although underground is a wet location in is also underground. A dip tank is a wet location but it is also a hazardous location.

The one thing that I get a lot of argument about is that the ?U? means ?direct burial? but I cannot find anything to back this. In Table 310.13 The only words used is ?underground? in 338.2 the only words used is ?underground? and in 338.10(B)(4)(b) the only word used is ?underground? in 340.2 is the first time we see the words ?direct burial?
In 340.10(1) it clearly states, ?For use underground, including direct burial in the earth.?
Here there is a distinction between ?underground and ?direct burial.? 338.10(B)(4)(b) tells us that USE can be installed in accordance of 340 thus giving us permission to install it as ?direct burial.?

In Article 310 at Table 310.13 we will find only three conductors that are listed for underground installations, ?UF?, ?USE? and ?PFA? 85 degree.
In my opinion any other conductor installed underground is in violation of the NEC whether in conduit or not.

Mike do you not see this as a straight forward issue?

As in 300.5(B)?

Listed for wet locations?

What am I missing here....anyone?

 

[JohnE]

I replied many times in the detached garage thread, but will continue any future responses here. This new thread is a good idea as thread titles are often misleading to what's currently being discussed in them.

 

[tom baker]

Take a look at the UL Cable and Wire Marking Guide.
It explains all the letters, but not sure about U

 

[jwelectric]

This debate started about SE-R being installed in a raceway undergound.
Using 338.10(B)(4)(b) and the UL Wire and Cable Marking Guide I made the statement that SE-R installed in a raceway underground would be a violation. Here is the link to the guide.

http://www.ul.com/regulators/W&CMG_March2006_Final.pdf

I also made the statement as outlined in the first post, I see the NEC states that there is a difference between ?underground? and ?direct burial? as outlined in several different sections. One of these is 340.10(1) For use underground, including direct burial in the earth.
The word including shows that there is a big difference between underground and direct burial.

Now the question stands, Does a conductor or cable installed in a raceway underground have to be listed for underground installations?

 

[ryan_618]

Now the question stands, Does a conductor or cable installed in a raceway underground have to be listed for underground installations?

No, it needs to be listed for a wet location.

 

[jwelectric]

Now the question stands, Does a conductor or cable installed in a raceway underground have to be listed for underground installations?

No, it needs to be listed for a wet location.

Then what is meant by the listings found in Table 310.13 under the header Application Provisions.
Does this have no bearing on how a conductor is to be installed?

 

[iwire]

It tells us which conductors are listed for wet locations which is all that is required of a conductor in a raceway underground.

You said I can install UF in a raceway underground.

Which depth requirement of Table 300.5 would apply?

Conduit or cable?

 

[mpd]

what is your point iwire?

 

[ryan_618]

I'm with Bob. 300.5(B) makes this a slam dunk case.

 

[iwire]

what is your point iwire?

It is a simple question that I was hoping Mike could answer based on his view of underground.

 

[Pierre C Belarge]

There is probably more cross referencing of references here than 1st meets the eye.
There is the definition of location, wet, there is Table 310.13, there is the "UL White Book", there are the UL marking cards, and there is specific conductor/cable types where the manufacturer may be of some help.

Letters such a U and other terms may be specific to a conductor/cable type. Sometimes it takes a little more work than we may want to put forward. That is where a forum like this is a tremendous time saver (sometimes :wink: ).
Take a peak at 310.7 and 310.8 as a start.

 

[George Stolz]

the problem is, 'underground' isn't defined. the ul guide even uses obscure language, noted when i originally posted the link to the guide.

i don't think mike is correct on this, but i don't see a ready way to correct him... there is a hole in the words. he's got a perch... :wink:

don't drink + type,

 

[jwelectric]

You said I can install UF in a raceway underground.

Which depth requirement of Table 300.5 would apply?

Conduit or cable?

It is a simple question that I was hoping Mike could answer based on his view of underground.

I would need more information on this such as is the raceway RMC, IMC or RNC.

Is the installation under 4 inches of concrete or under a highway or raod?

Is this installation under air port runways or is it an installation of 30 volts or less for landscape lights?

Any of this information can be found in Table 300.5.

 

[jwelectric]

the problem is, 'underground' isn't defined. the ul guide even uses obscure language, noted when i originally posted the link to the guide.

i don't think mike is correct on this, but i don't see a ready way to correct him... there is a hole in the words. he's got a perch... :wink:

don't drink + type,

Thank you George.

I love to debate an area that there could be doubt about and this is a real good one that you got me to bite into.

I will soon have an answer from UL as to their take on this and an explanation of their wire and cable guide. Till then, well you know what I will do. :lol:

Good night all

 

[iwire]

You said I can install UF in a raceway underground.

Which depth requirement of Table 300.5 would apply?

Conduit or cable?

It is a simple question that I was hoping Mike could answer based on his view of underground.

I would need more information on this such as is the raceway RMC, IMC or RNC.

Is the installation under 4 inches of concrete or under a highway or road?

Is this installation under air port runways or is it an installation of 30 volts or less for landscape lights?

Any of this information can be found in Table 300.5.

No you don't need more information. :lol:

The question is not what is the actual depth you would bury it.

The question is would you use the depth requirement for cable or raceway when running UF in a raceway?


Simple....don't try to make it hard 'cause it's not. :lol:

 

[jwelectric]

Conduit of course

 

[dlhoule]

Interesting topic: IMO things should be cleared up with a code change.
I can run conduit on the surface of the ground and run anything with a wet location rating in it, but if I bury that same conduit people are telling me that I can't run that same wire. IMHO if you are running conduit outside of a building you should be using wire suitable for a wet location.
This is true either above or below grade level.

 

[jwelectric]

There are a lot of things underground that are not found aboveground. A conduit strapped to the side of a building will be subject to rain, sun and maybe a little bird waste. Conduits and conductors underground could be subject to more deteriorating elements such as fertilizers and petroleum runoff.
I see a big difference between a conductor installed underground and one that is aboveground,

 

[dlhoule]

There are a lot of things underground that are not found aboveground. A conduit strapped to the side of a building will be subject to rain, sun and maybe a little bird waste. Conduits and conductors underground could be subject to more deteriorating elements such as fertilizers and petroleum runoff.
I see a big difference between a conductor installed underground and one that is aboveground,

Good point. So do I. I don't have to dig a trench when it is above ground. :lol: :lol:

Do you think the underground wire will hold up to these things better than RNC? I am really not sure about it. :?

 

[Gmack]

Still not impressed. Bob.

You have based your case on 300.5 Yes?

Well then please explain"

I. General Requirements
300.1 Scope
(A) All Wiring Installations This article covers wiring methods for all wiring installations unless modified by other articles.

I hear that slam dunk again.

Quit dodging the issue of the cable listings and "other" code articles that "modify".