Non-metallic Sheathed Cable

[planas]

Non-metallic-Sheathed Cable Type "NM-B"
can be used inside of conduits (metal or pvc)
for a High Rise commercial building (6 Fl or
higher)?

 

[don_resqcapt19]

Re: Non-metallic Sheathed Cable

Why would any one want to install NM cable in a raceway system??????? In my opinion the wording of the ".22" section of the raceway articles prohibits the use of cables in raceway systems unless specifically permitted in the cable article.
Don

 

[pierre]

Re: Non-metallic Sheathed Cable

Hello planas

I see you are an engineer, and maybe have not had the pleasure of pulling wire in pipe, especially up (or down) 6 stories. I agree with Don that it is not allowed in the NEC, also would be a big waste of time and money.

Pierre

 

[a.wayne3@verizon.net]

Re: Non-metallic Sheathed Cable

Aside from the labor aspect 334.30 does not allow nm to be in conduit.....any thoughts ??????

 

[pierre]

Re: Non-metallic Sheathed Cable

Hello Allen

Like Don has said, the xxx.22 of the raceway articles states that the cable articles have to permit the installation, I do not see that in the cable articles, so I say that it is not allowed, your xxx.30 may be used to substantiate that. My understanding of this is that the raceway CMP made this change and the cable CMP did not catch it, and that is to be addressed in the next cycle.

Pierre

 

[roger]

Re: Non-metallic Sheathed Cable

OK, at the risk of starting a war, I disagree that it is not allowed. Let's take article 334.12. (any xxx.12 in cable articles) Time was spent to list "Shall Not" uses, and installing in conduit is not listed.

I know I sound like a broken record but, I will point out again that article 400.8(6) specifically address this, and if the intent was the same for NM it would be addressed in article 334 in simular wording.

I don't see how 334.30 would prohibit this.

I echo Don's question and Pierre's points, I wouldn't see any reason to do this as a designed method.

Roger

 

[jim dungar]

Re: Non-metallic Sheathed Cable

Almost a thread jack.

How about UF cable in underground PVC?(do to mix up 1 guy bought 8/3 UF and the other guy buried 650' of 2" PVC)

The NEC 340.10(1) specifically says UF cable can be installed "...under ground, including direct burial..." (my emphasis).

If not direct burial the only other method is raceway isn't it?

 

[jro]

Re: Non-metallic Sheathed Cable

I disagree, NM cable can be installed in conduit NEC 334.15 (B), but agree that using NM in conduit to wire the 6 story building is a waste of time and money.

 

[bphgravity]

Re: Non-metallic Sheathed Cable

The way I look at it is that if NM is used, that becomes your wiring method. All rules and requirements for this method must be met. When you install NM inside conduit, you havent changed your wiring method, just the location of the wiring method and therefore unable to comply with the requirements of the NM section of the code. Using conduit for protection doesnt make it a raceway unless it is complete from termination to termination. The use of conduit with individual conductors is a wiring method and only the rules for the conduit need to be met. Individual conductors must be installed in a raceway of some kind.

I dont really see a problem with installing NM cable in conduit. As long as the conduit is secured and terminated properly, the NM should be supported and secured just fine.

I also dont see anything in the report of proposals on clarifing this issue from the code making panel that covers the NM section.

 

[tom baker]

Re: Non-metallic Sheathed Cable

Just a note on the xxx.22 section comments. I heard at a IAEI metting a cmp member, state that the cmp made a mistake on this section, there intent was not to limit NM or any cable in a raceway. What they wanted was where cable can't be used to be specified, it came out backwards, and will be corrected for the 05 cycle.

However why would you want to install NM in a raceway. First of all the raceway fill would be enormous! And the extra labor to strip off the jacket.

[ July 04, 2003, 04:40 PM: Message edited by: tom baker ]

 

[a.wayne3@verizon.net]

Re: Non-metallic Sheathed Cable

Roger I cited 334.30 (having been tagged for this exact installation) It specificaly states that nm be secured within 12 inches of cabinet / box / fitting

 

[pierre]

Re: Non-metallic Sheathed Cable

Reading the responses, I understand it was an oversight by the 2 CMP's, and I have also heard (probably at the same IAEI meeting as Tom)that it is to be addressed. For arguments sake, lets say NM is 'permitted' to be installed in a raceway, except for physical protection reasons, I cannot understand why anyone would want to.

Pierre

 

[iwire]

Re: Non-metallic Sheathed Cable

To keep it going I have not seen anyone mention that you can run multiple NM cables through EMT (or any raceway) unstriped into the top of an enclosure for up to 10' without more than a bushing where you enter the EMT as long as you are secured within 12" of the end of the raceway.


2002 NEC 312.5(C)

Exception: Cables with entirely nonmetallic sheaths shall be permitted to enter the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 450 mm (18 in.) or more than 3.0 m (10 ft) in length, provided all the following conditions are met:
(a) Each cable is fastened within 300 mm (12 in.), measured along the sheath, of the outer end of the raceway.
(b) The raceway extends directly above the enclosure and does not penetrate a structural ceiling.
(c) A fitting is provided on each end of the raceway to protect the cable(s) from abrasion and the fittings remain accessible after installation.
(d) The raceway is sealed or plugged at the outer end using approved means so as to prevent access to the enclosure through the raceway.
(e) The cable sheath is continuous through the raceway and extends into the enclosure beyond the fitting not less than 6 mm (1/4 in.).
(f) The raceway is fastened at its outer end and at other points in accordance with the applicable article.
(g) Where installed as conduit or tubing, the allowable cable fill does not exceed that permitted for complete conduit or tubing systems by Table 1 of Chapter 9 of this Code and all applicable notes thereto.

So yes you can run NM in EMT 312.5(C) exception and 334.15(B) and no you can't run NM in EMT 358.22.

Clear as mud.

Bob

Oh I forgot to ask, why in the world would you want to run NM in the EMT?

Do you mean just short sections for physical protection, which is OK or the whole job which is up for debate?

[ July 04, 2003, 04:18 PM: Message edited by: iwire ]