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Posted By: aldav53 Romex in pipe - 12/11/01 06:56 AM
I can't see any reason why you can't run romex in emt even when using compression fittings? Seems safe to me.
Posted By: sparky Re: Romex in pipe - 12/11/01 11:01 AM
To be compliant, the notes to chap 9 should be met. also compression insinuate wet/damp location, so the wire would have to follow suit.
[Linked Image]
Posted By: Redsy Re: Romex in pipe - 12/11/01 12:09 PM
I had an argument with the "Pro" at sell-all supply house. I maintain that if conduit is installed in a wet location, the interior or that conduit is a wet location, and wiring should be rated accordingly. He looked at me like I was from Mars, and insisted that the PVC conduit made it a dry location. Then he told me that he should know, because he is an electrician. (Don't ask me questions bud, just give me my UF)!!
BTW,
Also there may be other issues about complete raceway systems.
Posted By: rkukl Re: Romex in pipe - 12/11/01 11:13 PM
Its common practice in my area to see the following. “Appropriately” sized PVC buried to supply a separate building with the PVC stubbed into the basement with a fitting “male adapter” and sometimes a bushing and the same at the other end. Then to have SER cable pulled in and run to the panel and sub-panel in the out building. I think that this is ok, one reason is that the conductors in the SER are XHHW rated for wet locations. What do the rest of you think?
Posted By: resqcapt19 Re: Romex in pipe - 12/12/01 12:45 AM
Redsy,
The new code makes it very clear that you can't use NM in an underground conduit.
"300.5(D)(5) Listing. Cables and insulated conductors installed in enclosures or raceways in underground locations shall be listed for use in wet locations."
Don(resqcapt19)
Posted By: aldav53 Re: Romex in pipe - 12/12/01 06:44 AM
Still seems like NM would be fine in conduit as long as it is a weatherproof installation. THHN wire is allowed so why not NM.
Posted By: Joe Tedesco Re: Romex in pipe - 12/12/01 07:57 AM
THHN is not permitted to be used in a wet location. See Table 310-13

[This message has been edited by Joe Tedesco (edited 12-24-2001).]
Posted By: Redsy Re: Romex in pipe - 12/12/01 01:49 PM
Don,
My application was actually above ground, outdoors. I still say the interior is a wet location. I don't think the previous code was as clear on this. I often see NM run in PVC up the side of a house to get circuits in the attic for distribution throughout the second floor. I believe UF would be acceptable.

rkukl,
I would say that SER is not approved for underground use. Even in conduit. It may be debatable, especially now with the wording of 300.5 (D)(5), but I believe USE would have been be the proper method. See 338.2


[This message has been edited by Redsy (edited 12-12-2001).]
Posted By: sparky66wv Re: Romex in pipe - 12/12/01 02:38 PM
What about THHN with a THWN listing?

Or said another way... I've never seen THHN without a THWN listing...
Posted By: aldav53 Re: Romex in pipe - 12/12/01 03:16 PM
THHN is allowed underground in ridgid pipe wrapped with pipe wrap, isn't this considered damp or wet location?
Posted By: Bill Addiss Re: Romex in pipe - 12/12/01 06:56 PM
Al,

I think if you look closely at the wire you will see that it says both THHN and THWN meaning it is approved as both.

Bill
Posted By: motor-T Re: Romex in pipe - 12/12/01 09:39 PM
Bill:
Is Romex rated both thhn and thwn ? I know stranded wire is rated both but I think Romex is only rated for dry locations. Ergo, pvc under ground would be considered a Wet-location. No ?
Posted By: Nick Re: Romex in pipe - 12/13/01 01:50 AM
Quote
THHN is allowed underground in ridgid pipe wrapped with pipe wrap, isn't this considered damp or wet location?
Where do you find that this is allowed?
Posted By: Bill Addiss Re: Romex in pipe - 12/13/01 04:22 AM
-T

>>Is Romex rated both thhn and thwn ? I know stranded wire is rated both but I think Romex is only rated for dry locations. Ergo, pvc under ground would be considered a Wet-location. No ?<<

You're correct. I think we're talking about 2 different things here at the same time. I was saying to Al, that, what we commonly call THHN is also (always?) labelled and rated THWN if you look at the wire. Maybe that was why He thought THHN would be allowed in conduit outside and underground.

Bill

[This message has been edited by Bill Addiss (edited 12-12-2001).]
Posted By: Redsy Re: Romex in pipe - 12/13/01 12:10 PM
Isn't it the clear plastic coating on THHN/THWN that makes the W possible in THWN?.

BTW,
Does a conduit installed above ground outdoors require wiring rated for wet locations? I say yes. Supply house man says no.

[This message has been edited by Redsy (edited 12-13-2001).]
Posted By: Bill Addiss Re: Romex in pipe - 12/13/01 01:42 PM
Redsy,

I don't know about the plastic covering, but I read in an NEC Handbook that the intent was that the interior of a conduit (outside) be considered a wet location. I've also heard that from a UL rep when it was brought up at a local meeting.

Bill
Posted By: aldav53 Re: Romex in pipe - 12/13/01 03:27 PM
Responding to Nick,
Why wouldn't THHN be allowed underground, if it is completely weatherproof. How else would you run circuits underground not using UF?
Posted By: sparky66wv Re: Romex in pipe - 12/13/01 03:51 PM
THWN is allowed... And I'm betting dollars to donuts that your THHN is also marked THWN and therefore compliant...



[This message has been edited by sparky66wv (edited 12-13-2001).]
Posted By: resqcapt19 Re: Romex in pipe - 12/13/01 03:52 PM
aldav53,
There is no such thing as a dry underground conduit. You must us a wet location wire. Air moves in and out of the conduit carrying with it water vapor. When the air cools in the conduit the water vapor condenses out leaving water in the conduit. Over a period of time the conduit will fill with water.
Don(resqcapt19)
Posted By: Redsy Re: Romex in pipe - 12/13/01 04:57 PM
aldav,

The whole point is, underground conduits are not weatherproof at all. The "W" is required in the designation if it is to be installed in a wet location. Look at table 310.13 and notice that all (except MI) conductors allowed in wet locations have a "W" in the (Type Letter) column.
Posted By: aldav53 Re: Romex in pipe - 12/14/01 03:16 PM
When I say THHN, I mean THHN and THWN. I just wanted to make the point that they both are OK to use in wrapped ridgid pipe underground.

[This message has been edited by aldav53 (edited 12-14-2001).]
Posted By: sparky Re: Romex in pipe - 12/14/01 10:29 PM
Quote
Air moves in and out of the conduit carrying with it water vapor. When the air cools in the conduit the water vapor condenses out leaving water in the conduit
My first encouter with a wic used on an outside Rigid run made this clear.
Posted By: Nick Re: Romex in pipe - 12/15/01 04:10 AM
As stated above THHN is not allowed in a wet location. Also as stated above most of us have not seen THHN that was not also rated THWN.
Again as stated above underground conduit is a wet location. It doesn’t matter if it’s PVC, Rigid or what ever. If you had conductors marked THHN only it would be a violation to install them in underground conduit.
Posted By: electure Re: Romex in pipe - 12/15/01 12:59 PM
(Chiming in)
The individual conductors in type NM may be rated as THWN, but the overall cable assembly is not rated for wet locations. The paper filler will wick water like crazy.
THHN/THWN is not rated as wet location because of the nylon coating N. It is rated by the W. Type TW and type THW are both rated for wet locations, and don't have the nylon jacket.
Posted By: aldav53 Re: Romex in pipe - 12/22/01 02:59 PM
Electure, what do you mean when you say the paper in the NM cable will wick, even if it does get wet, the W rating on the jacket of the NM wire itself should protect it from the wet location.. right?
Posted By: resqcapt19 Re: Romex in pipe - 12/22/01 07:21 PM
aldav53,
It doesn't matter what the wire type is in the NM cable. 336-4(a) restircts NM cable to normally dry locations.
Don(resqcapt19)
Posted By: sparky66wv Re: Romex in pipe - 12/23/01 04:17 AM
And yes, I've seen it wick moisture and cause a volt-tic to give false "off" readings on live cable. (I learned the easy [non-violent] way by noticing that said cable was feeding a burning lamp...)

I must say that NM cable in conduit (outdoors) is one of the most common violations here... usually stuffed in 1/2" pipe (and sometimes with plumbing ells!)...

How'd they do it?
Posted By: aphares Re: Romex in pipe - 12/23/01 05:13 AM
2002 NEC should clear this up.
334.12 Uses not permited.
Types NM,NMC, and NMS
(A)d. Where exposed or subject to excessive moisture or dampness.
Definition of wet location covers, (Instalations underground.)
Posted By: electure Re: Romex in pipe - 12/23/01 02:52 PM
Al,
Take apiece of NM cable. Put one end in a bucket of water. Come back the next day and the other end will be wet.
Posted By: dons Re: Romex in pipe - 12/24/01 05:10 AM
ohhh water cooled conductors.....no derating
Posted By: aldav53 Re: Romex in pipe - 12/24/01 04:23 PM
Some very good points on why not to use NM wire in EMT, they do make sense.
Of course, here in Arizona we don't have to worry much about moisture.
(Also just wanted to point out, you can use NM in EMT for mechanical protection in a dry invironment).
Posted By: frodo Re: Romex in pipe - 12/30/01 07:11 PM
hi,
ok how about this...an fs box is mounted on an exterior wall of a single family dwelling...once the cable enters the fs box it is stripped and then the conductors are run in a pvc conduit to a shed...120VAC...

where is the problem?

how about a sub panel in a attached garage with a 2" piece of pvc sch 40 extended into the cieling, filled with several 12/2, 12/3, 3C/6?

is this legal?

-regards

frodo
Posted By: amp-man Re: Romex in pipe - 12/31/01 05:27 AM
Frodo,

If that PVC conduit runs underground, then there's a problem if the conductors are not THWN. I dunno if NM-B conductors are dual THHN/THWN, and I'm too comfortable to get up, go to the garage, and look.

On the 2" PVC running from a surface mount panel to the attic space--look at table 310.15(B)(2)(a) "Adjustment Factors for More Than Three Current-Carrying Conductors in a Raceway or Cable". If the length of the pipe is more than 24", these factors must be applied (310.15(B)(2)(a).

Also, in Annex B, Table B.310.11 gives adjustment factors for more than 3 current-carrying conductors in raceway or cable with load diversity. Because of the load diversity, you don't have to give up as much ampacity. I think you'd have a tough time getting an AHJ to agree to this approach (load diversity) in a dwelling occupancy.

Cliff
Posted By: Glenn Re: Romex in pipe - 12/31/01 01:55 PM
Cliff,
Have you read the italics, the second line, under ' Annex B - - - - '?
Posted By: Redsy Re: Romex in pipe - 12/31/01 03:53 PM
I believe the basic answer is:

1)NM cable is not approved for wet locations, regardless of the conductors on the inside. The covering will absorb moisture and due to the wicking phenomena, the paper filler will draw moisture into whatever enclosure the NM terminates in.
2)If any conduit is installed in a wet location,(outdoors or underground) the interior of that conduit is also a wet location. Therefore no NM.
Posted By: aldav53 Re: Romex in pipe - 12/31/01 04:36 PM
Most all the breaker panels on homes here in Arizona are mounted on the outside of the house in a weatherproof panel, (a wet location during the short monsoon season) which means all romex terminations are in a wet location. umm..
Posted By: aldav53 Re: Romex in pipe - 01/04/02 12:38 AM
Any comments about the outdoor breakers panels?
Posted By: Redsy Re: Romex in pipe - 01/04/02 02:37 AM
I'll give it a try-

Conduits in wet locations may fill with water and if underground, will probably never dry out. If NM cable is inside, the jacket will become saturated and the paper filler will transmit moisture to the termination points. An outdoor breaker panel will probably never fill with water and has 90% of the jacket & paper removed anyway. It seems unlikely that enough moisture will be present to cause any problems.
But that's just my opinion.
BTW,
I don't like the idea of outdoor residential panels anyway. Are they that common, guys?
Posted By: aldav53 Re: Romex in pipe - 01/04/02 05:25 AM
I never really thought outdoor breaker panels outside were a great idea either, but never-the-less probably 99% here in AZ are outdoor. They are "all in one" type - meter and breakers combined in one panel.
Posted By: resqcapt19 Re: Romex in pipe - 01/04/02 01:20 PM
If they are in a 3R type enclosure, the wiring and terminations are not supposed to be getting wet. The NEMA test requirement for 3R panel is the entire top, and all exposed sides are sprayed with water at 5 psi for one hour at a rate to cause water to rise 18" in a straight sided pan placed beneath the enclosure. The evaluation is: no water shall have reached live parts, insulation or mechansims. If the panel is a NEMA 4 or 4X then the same test is used but the evaluation is: no water shall have entered the enclosure.
Don(resqcapt19)
Posted By: mustangelectric Re: Romex in pipe - 09/09/04 11:36 PM
question on the subject of NM in undergound systems..if you REMOVE the jacket of an NM cable and use the wires in a underground system..is this a violation other than the wires are NOT marked as required?

i admit to stripping short pieces of NM to feed an AC unit or outlet.

are the conductors in NM rated THWN?
Posted By: electricman2 Re: Romex in pipe - 09/10/04 12:32 AM
Why would anyone go to the trouble to strip NM when it is so much easier to pull in single conductors? [Linked Image]

[This message has been edited by electricman2 (edited 09-09-2004).]
Posted By: mustangelectric Re: Romex in pipe - 09/10/04 02:18 AM
electricman2,
have you ever been short of material?

the key word was SHORT..i am not talking about anything more than 6 feet..

that was the point of the question..what is the concensus or opinions on the use of the CONDUCTORS CONTAINED IN NM cable..they are thhn aren't they? they are not marked as to size, type, manufacturer etc. or have any temp ratings..

i could make a Billion dollars replacing all the NM cable that is outside the building..

i am not saying it is right..but people will continue to use it..

thanks

mustang
Posted By: gfretwell Re: Romex in pipe - 09/10/04 04:11 AM
The problem with using NM-b is you really don't know what the conductors are insulated with. They are listed as a dry location wiring method so the manufacturer has no obligation to use a "w" type insulation.
Considering the way companies work, if they could save a penny a box using cheaper wire they will.
Posted By: macmikeman Re: Romex in pipe - 09/13/04 02:25 AM
Hi gang, Does anyone know what the "r" means in type ser cable?. I cannot find type ser cable in table 310-13, and article 338 has cable types se and use. 2nd question I have is type ser actualy an se type cable?. Reason bieng is I have often seen it passed while installed underground in pvc, and I have a customer who wants to get an existing 100 amp panel fed this way upgraded by replacing the feeder to a larger size, (conduit is 2" pvc sch 40), but I have not sent any quote back because I don't want to do the job if it isn't the right way to go.
Posted By: gfretwell Re: Romex in pipe - 09/13/04 03:56 AM
"SER" is actually Type SE cable style SER or simply style R as opposed to the regular style U. Maybe it means "round" since it usually is?

You follow the regular SE rules.
Posted By: energy7 Re: Romex in pipe - 09/21/04 12:15 AM
My two cents:
NM as a wiring method (cable, no conductors!) is not to be "mixed" with other methods. i.e. don't run in EMT. Overheating is the problem. And isn't that the main factor in many of the NEC 70 art.'s.
As for what NM is: most of the conductors are not marked; NEC 336 indicates that it is a 60 degree cable assembly. One piece that I have did have conductor marking: "TW" (60 deg. conductor, what do you know!).
Posted By: interom Re: Romex in pipe - 09/21/04 03:25 AM
How you

How you "properly terminate" an NM cable in a conduit ??????
Posted By: Norstarr Re: Romex in pipe - 09/27/04 04:09 AM
I believe if you strip nm-b cable you will find that there is no marking on the conductors. They are thhn but because it is not stamped into the conductor you cannot run a long piece into a box, strip the outer sheathing and then continue it through another conduit. This would create a violation of 310.11 (Marking)
NM-B cable is not permitted in a wet location because it is not dual rated. The conductors inside are thhn which means "thermoplastic (t) 60 degree C rating (h) +30 degrees (h) making it rated at 90 degrees C and nylon jacketed (n). Rated for dry and damp locations only.
The inspectors in my area will not permit romex to be installed in a short piece of emt going to the back of an AC disconnect for that reason. Either UF or a raceway with wet location rated conductors.
Hope this helps to clear things a little.
Posted By: tdhorne Re: Romex in pipe - 09/27/04 11:21 PM
Quote
I would say that SER is not approved for underground use. Even in conduit. It may be debatable, especially now with the wording of 300.5 (D)(5), but I believe USE would have been be the proper method. See 338.2

Type SE cable is suitable for use underground but type USE is unsuitable for use inside buildings becuase the jacket is not fire retardent. The U in the type designation is to indicate that the cable is not suitable for use in buildings.
--
Tom Horne
Posted By: cpal Re: Romex in pipe - 09/27/04 11:35 PM
Type USE that does not contain additional insulation designators such as XHHW, RHW, and MTW, is not subjected to the UL vertical flame test and therefore is unsuitable for interior use. The NEC in 338.10 allows up to 6 feet of the USE only to terminate in buildings.

The following is from the UL listing guide for wire and cables

This category covers service entrance cable designated Type SE and Type USE for use in accordance with Article 338 of ANSI/NFPA 70, “National Electrical Code” (NEC).
Service entrance cable, rated 600 V, is Listed in sizes 14 AWG and larger for copper, and 12 AWG and larger for aluminum or copper-clad aluminum. Type SE cable contains Type RHW, RHW-2, XHHW, XHHW-2, THWN or THWN-2 conductors. Type USE cable contains conductors with insulation equivalent to RHW or XHHW. Type USE-2 contains insulation equivalent to RHW-2 or XHHW-2 and is rated 90°C wet or dry. The cable is designated as follows: Type SE — Indicates cable for aboveground installation. Both the individual insulated conductors and the outer jacket or finish of Type SE are suitable for use where exposed to sun. Types USE and USE-2 — Indicates cable for underground installation including direct burial in the earth. Cable in sizes 4/0 AWG and smaller and having all conductors insulated is suitable for all of the underground uses for which Type UF cable is permitted by the NEC. Types USE and USE-2 are not suitable for use in premises or aboveground except to terminate at the service equipment or metering
equipment. Both the insulation and the outer covering, when used, on single and multiconductor Types USE and USE-2, are suitable for use where exposed to sun.
40


Charlie
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