ECN Forum Forums Code Related Discussion NEC & other Code issues Romex in pipe

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?

Why would anyone go to the trouble to strip NM when it is so much easier to pull in single conductors?

[This message has been edited by electricman2 (edited 09-09-2004).]

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

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.

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.

"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.

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!).

How you

How you "properly terminate" an NM cable in a conduit ??????

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.

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.
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Tom Horne