Type 'W' Conductors

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JohnE

Senior Member
Location
Milford, MA
Gmack said:
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".


I'm not sure which issue you are addressing. Conductors with a "W" designation, SE cables, or something else?

I didn't hear your slam dunk, sounded more like rattling off the rim.
 

iwire

Moderator
Staff member
Location
Massachusetts
Gmack said:
Still not impressed. Bob.

How will I survive. :p

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

Gmack please do not mix these threads I separated them for a reason.

This thread has to do with single conductors, not cables at all.

You want to hammer me on the cables do so in the detached garage thread.


Gmack said:
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.


What article modifies 300.5(B) in regards to single conductors?

He throws, its a swish and he scores from 3 point land. :lol:
 

Gmack

Banned
Location
Michigan
Im just catching up with this and the other thread.

Bob, you cited someone else for not explaining:

230.30 Insulation
Service-lateral conductors shall be insulated for the applied voltage.
Exception: A grounded conductor shall be permitted to be uninsulated as follows:
(1) Bare copper used in a raceway.
(2) Bare copper for direct burial where bare copper is judged to be suitable for the soil conditions.
(3) Bare copper for direct burial without regard to soil conditions where part of a cable assembly identified for underground use.
(4) Aluminum or copper-clad aluminum without individual insulation or covering where part of a cable assembly identified for underground use in a raceway or for direct burial.

I posted that code days back. Whats to explain under exception [4]?

I even said that we were talking about a detached garage with SE cable. I provided OEM links for SE and could not find "any" identification for use in a raceway underground. ZIP!

Well if its no good for a service underground in a raceway its no good for a feeder to a detached gararge either.

Exception [4] must have been on the CMP mind to require a identification/listing/labeling etc for what would seem "common sense"

Feeding and pulling SE cables meant for above ground use without conduit in an extended "underground conduit" would be beneath us all here as professionals in such a learned community.

Its fun and educating and all the rest but really your side has blundered on the EC's nightmare.

Identification,Listing and Labeling AND the NEC itself.
 

iwire

Moderator
Staff member
Location
Massachusetts
Gmack I am not going to talk about SE cable in this thread.

This thread is about single conductors with 'W' in their designations such as:

TW

THWN

RHW

etc.

If you want to talk about the SE cables lets do that in the detached garage thread. :)
 

Gmack

Banned
Location
Michigan
OK Bob,

Like I said I was just catching up and I thought you moved the debate from "detached garage" to here.

My mistake.

I guess then I dont yet know what all the fuss is about. :?:

BTW, I was not "hammering you". Just exhorting.
 

Gmack

Banned
Location
Michigan
Yep, this thread is straight forward.

A wet location is:

Location, Wet. Installations under ground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather.

NEC 2005 Commentary:

It is intended that the inside of a raceway in a wet location or a raceway installed underground be considered a wet location. Therefore, any conductors contained therein would be required to be suitable for wet locations.

See 300.6(D) for some examples of wet locations and 410.4(A) for information on luminaires installed in wet locations. See patient care area in 517.2 for a definition of wet locations in a patient care area.

Conductors in conduit "underground" must be suitable for wet locations and not have/bear a "specific" U listing.

.
 

iwire

Moderator
Staff member
Location
Massachusetts
Gmack said:
BTW, I was not "hammering you". Just exhorting.

Either is perfectly acceptable.

If I give it out (and I do :wink: ) I have to be able to take it.

Gmack said:
Yep, this thread is straight forward.

.......................Conductors in conduit "underground" must be suitable for wet locations and not have/bear a "specific" U listing.

Well than you and I agree leaving only Mike that thinks these conductors must be listed for 'underground'. 8)
 

jwelectric

Senior Member
Location
North Carolina
As most know I will do what I can to keep a debate alive looking for that 1000 post thread.

This thread along with the debate of SE-R installed underground would be a good thread to make the 1000 post.

To stay in line with this thread I have a couple of sections of the NEC that might have some bearing on this.

Some have made the comment that 338 and 340 are for direct burial conductors although 310.7 addresses direct burial conductors.

338.2 defines a USE conductor as an underground conductor and nowhere in 338 does it refer to the USE conductor as a conductor for direct burial.

340.10(1) states
For use underground, including direct burial in the earth. For underground requirements, see 300.5.
Notice it is not referring us to table 300.5 but to the section which would include (B) listed for use in wet locations. This section also mentions both "Direct Burial" and "Underground" as being two separate places.
310.9 Corrosive Conditions
Conductors exposed to oils, greases, vapors, gases, fumes, liquids, or other substances having a deleterious effect on the conductor or insulation shall be of a type suitable for the application.

Who can say just what the PH level of the soil is 6 to 24 inches under the earth.
This is why I have posted Table 310.13 and the Application Provisions listed in the table.

Then we have the UL?s letter designations assigned to wire. If it is listed for direct burial it will be marked ?FOR DIRECT BURIAL,? ?DIRECT BURIAL,? ?DIR BUR? or ?DIR BURIAL? and for underground use it will be marked with a ?U?

These things cannot be squelched by 300.5(B) as this section does nothing more than say that a conductor installed underground in a raceway or enclosure must be listed for a wet location.
If the only requirement was for the conductors to be listed for a wet location then I would install THW conductors to a gas pump and 501.20 could be deleted form the code book.

It will take something more that 300.5(B) to convince me that the other sections of the code and UL?s listing does not come into play in some way with underground conductors.
:)
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Location, Wet is a defined term (Art 100) and it includes underground locations. Single conductors listed in Table 310.13 are only permitted to be installed per a Chapter 3 wiring method [300.3(A) ? the exception is irrelevant in this discussion].

Various raceways are permitted underground per Chapter 3 and there is no general prohibition against Table 310.13 single-conductors.

Cables and conductors in underground locations shall be listed for ?Wet Locations.? [300.5(B)]

Therefore, single conductor cables listed for Wet Locations are permitted in underground locations in raceways installed per Chapter 3.

QED

Note: 300.5(B) is really unnecessary to the current discussion since ?underground locations? are automatically included in ?wet locations.? (We didn't need to wait until 2005 to discover it was OK) ? The ?U? designation is only a special case which permits direct burial and its lack is not a general restriction on "W" only conductors.

This is why we need ?Rules of Interpretation? beyond 90.4. We often try to give "general" application for specific rules -or vice versa, we may try to limit general rules to only specific applications.
 

jwelectric

Senior Member
Location
North Carolina
rbalex said:
QED

Note: 300.5(B) is really unnecessary to the current discussion since ?underground locations? are automatically included in ?wet locations.? (We didn't need to wait until 2005 to discover it was OK) ? The ?U? designation is only a special case which permits direct burial and its lack is not a general restriction on "W" only conductors.

Then why does UL make these statements

When evaluated for direct burial use, the product is marked ?FOR DIRECT BURIAL,? ?DIRECT BURIAL,? ?DIR BUR? or ?DIR BURIAL.?

U ? Underground use

Does not UL see the two as being different? :?:
 
Mike
Reading through the UL Marking Guide, I see very little use of "U". I, from my limited experience have only seen "U" used with SE cable (USE).

Direct Burial I have seen more often. I do not think that UL sees this as two distinctly different terms, but may have adopted "U" when the manufacturer used the term for USE... just hypothesizing.

Conductors with the "W" in the lettering scheme can be used in raceways "underground" or any other wet location. I would not be concerned about soil conditions for conductors installed in raceways underground if the soil conditions are not favorable, I would be concerned about the raceway's suitability itself first.
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
jwelectric said:
Then why does UL make these statements

When evaluated for direct burial use, the product is marked ?FOR DIRECT BURIAL,? ?DIRECT BURIAL,? ?DIR BUR? or ?DIR BURIAL.?

U ? Underground use

Does not UL see the two as being different? :?:

Oh there are MANY things about UL Standards I can?t explain ? and since you were so kind to provide the link I?ll give you a few examples:

Like on Page 17 the Designator ?W? for Table 310-13 conductors only means ?Moisture Resistant;? yet the Example at the bottom RHW means ?Thermoset Insulation, 75?C Wet?

Again on Page 17 ?U? indeed means ?Underground use;? but on Page 7, the Table for Wire and Cable Markings, NONE of the wires listed under Article 310 use the ?U? designator.

Where the ?U? designator is used is for Cables NOT Wires.

When you continue on with the notes to Table 1, you find on Page 14:

DIRECT BURIAL
?Yes? indicates that the wire or cable has been evaluated for direct burial in the earth. Generally not marked on the product. Notes in the tables indicate the following:
(50) When evaluated for direct burial use, the product is marked ?FOR DIRECT BURIAL,? ?DIRECT BURIAL,? ?DIR BUR? or ?DIR BURIAL.?
rbalex italics added

The fact is SE, USE and UF (cables) don?t really belong in Table 310-13 at all since they are wiring methods in and of themselves similar to Type TC or MC.

The UL Standards are like the Code, it has inconsistencies, unintended consequences, misprints, etc and when we make interpretations based on them they create some strange and usually unnecessary problems.
 

jwelectric

Senior Member
Location
North Carolina
Now I have an answer that I can accept. Here is a reply I got from UL

Hi -

Since these descriptions are not clear to you, I'm going to revisit the wording with a view towards improving it. Perhaps the following will help:

1. ''Underground" and "Direct Burial" are not necessarily the same. "Underground" can mean installed in, and protected by, conduit. Underground in conduit is a wet location and a wet rated wire is permitted there. Direct burial, besides wet location, also allows for the cable to be placed directly in the ground, with no conduit protecting it, and backfilled with dirt (including any rocks that may be present) - which means these cables must be able to withstand abuse more than they would if they were protected by a conduit.

2. The "U" really stands for direct burial. The cables where the "U" is used, such as USE and UF, are inherently permitted to be directly buried so the "direct burial" marking is not used. On the other hand, a Type TC Tray Cable is not normally rated for direct burial - that is an optional rating. So in that case the "direct burial" marking is needed.

I hope the above rambling is clearer than the Marking Guide. If not, please give me a call.

Regards,

Austin

*******************************************

Austin D. Wetherell
Principal Engineer (PDE) - Wire & Cable
Underwriters Laboratories Inc.
Melville, NY Office
:)
 
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