NM cable in EMT

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bphgravity

Senior Member
Location
Florida
Re: NM cable in EMT

It is not going to matter very much what we say. The inspector is the AHJ and will have the final word. I know it is a common practice to install cable systems inside conduit, but I still hold that it is a violation. I would ask for specific code reference or actual code interpretation from the inspector in any case. It is the least he can do.
 
R

roger deas

Member
Location
North_Carolina
Re: NM cable in EMT

Let's look at some definitions.

Article 100 RACEWAY
(shortened) An enclosed chanel of metal or nonmetallic materials designed expressly for holding wires, cables, or bussbars.
Raceways include, electrical metalic tubing

Nonmetalic-Sheathed Cable

A factory assembly of two or more insulated conductors having an outer sheath of nonmetalic material.

EMT
An unthreaded thinwall raceway of circular cross section designed for the physical protection and routing of conductors and cables

RMC
worded the same as EMT

PVC
Only mentions conductors not cables

Mark, by the wording of EMT and RMC your installation would be legal.

PVC
No, go figure. ;)

Roger
 
B

bphgravity

Senior Member
Location
Florida
Re: NM cable in EMT

roger, 344.22, and 358.22 clearly state that "cables shall be installed where such use IS PERMITTED by the respective cable articles. Nowhere in Article 334.10 does it say NM can be installed within these raceways. If you look at Article 336.10 for Type TC, # 2 allows TC in raceways. Other cable systems are indeed allowed. NM and UF are two that are not.
 
don_resqcapt19

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Re: NM cable in EMT

I agree with bph on this one. The xxx.22 sections in the raceway articles say you can't use the cable in the raceway unless specifically permitted in the appropriate cable article. Tom B. has indicated that this was not the intent of the xxx.22 sections, but it is what the words say. Maybe this will be resolved in the 2005 code.
As far as the original question, in my opinion all outside conduits are wet locations and NM cable is not permitted in a wet location.
Don
 
R

roger deas

Member
Location
North_Carolina
Re: NM cable in EMT

Don, and Bph, I don't see the word "specifically" in any of the xxx.22 articles. With that said, I don't see where article 334 prohibits this in anyway.

If it were prohibited, why did 400.8(6) make a point of wording this prohibition in that article and 334 didn't prohibit in that article?

Roger
 
B

bphgravity

Senior Member
Location
Florida
Re: NM cable in EMT

Well, everyone certainly has their own interpretation of the code's intent, I'm just glad I am finally on the side of DON! :eek: I still suggest ensuring local codes and the AHJ will approve since this is not a clear matter. It sounds like a good proposal topic.
 
russ

russ

Senior Member
Location
Burbank IL
Re: NM cable in EMT

I don't mean to try to have the last word, but no reply is ok with me.
334.15 Exposed Work
334.15(B) Protection from Physical Damage. The cable shall be protected from physical damage where necessary by conduit, electrical metallic tubing, schedual 80 PVC (BLA BLA BLA) or by other means.
This sentence seams to stand on its own, and never puts a limt on the length of the raceways mentioned.

Russ

[ March 25, 2003, 02:36 PM: Message edited by: russ ]
 
J

jackie

Member
Location
Texas
Re: NM cable in EMT

339-3-4 and 336-18 and ul green book will tell you that cable ties are approved for outside use and for securing cables.I hope this helps.
 
goldstar

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
Re: NM cable in EMT

Bphgravity,

:eek: I do not think or have ever thought that you or anyone in this forum has come off as being rude nor would I expect that anyone would think that of me. This is a great place to have these discussions whether we are right or wrong about the topics we discuss. The great thing about this forum is that you can usually get some great answers to specific situations within a 24 hour period and from rather knowledgeable people.

Anyway, back to supporting NM cable. If you sleeve NM cable inside a length of EMT for protection in an unfinished area and use a "from-to" connector like the one Iwire posted, as long as you have the EMT properly supported to the wall why should there be an issue as to whether the NM cable is properly supported ? Wouldn't you consider this done in a neat and workmanlike manner ?

With respect to ty-wraps, why do they make them ? Aren't you supposed to be able to ty-wrap cables together ? Are they made only for control panel bundling of wires ? If I had a straight NM cable run of about 50' and realized that I had to make another 50' run, would it be wrong of me to ty-wrap another NM cable to the one I just stapled to a joist or should I staple the new NM cable over the one I just ran ?

The AC contractor runs his condenser lines out the side of the house and down to the compressor. He wraps the condenser lines in Armor-flex and ty-wraps them together along with the control wiring from the blower unit. As long as the condenser lines are going to be enclosed in a piece of aluminum leader what would be wrong with ty-wraping a UF cable to the condenser line ? If he has to make a repair to the condenser line not only would he have to cut off my ty-wraps but his also.

Please tell me what you would do to make this installation correct.
 
M

markf

Member
Location
Colorado
Re: NM cable in EMT

WOW! I really started a good one and I thank all of you for your interpretations. 90-4 does give the AHJ "interprative" powers. (sorry if there are spelling errors) However I always thought the AHJ had to at least quote a reference from "the Book". This guy can't even do that. Sounds like we're at his mercy though, so we'll play the game his way.

This is a great forum for discussing ideas and problems. Thanks for all of the comments and suggestions.

Mark
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Re: NM cable in EMT

Originally posted by russ:
334.15 Exposed Work
334.15(B) Protection from Physical Damage. The cable shall be protected from physical damage where necessary by conduit, electrical metallic tubing, schedual 80 PVC (BLA BLA BLA) or by other means.
This sentence seams to stand on its own, and never puts a limt on the length of the raceways mentioned.
Russ
Click to expand...
I agree 100%

Don, you mentioned to me that you do not do "rope" jobs so maybe you do not run into this.

A very common application for us is MC or NM in a suspended ceiling (I am from MA we can still run NM in suspended ceilings) and use a change over to come down the wall in raceway to outlets and switches.

This practice is not limited to branch circuits, 200 amp feeder in MC above a ceiling change over to raceway with MC Connector/Conduit Coupling/EMT Connector drop down the wall to a panel. We work all over New England so we take inspections from many different inspectors and this is never questioned. Either all these inspectors are blind or this is not a violation.

I do not under stand the support argument, the wire is in a raceway how much more support can you get, what is going to happen to the wire?

The change over fitting provides strain relief and the wire will be supported within 12" of there anyway.
 
B

bphgravity

Senior Member
Location
Florida
Re: NM cable in EMT

Bob, the point you are missing about support is not when installed in a raceway. I believe the code does not allow it, but that doesn't matter. If you run a peice of conduit from one box to the next with an approved means of connection, and support the conduit properly, than it is a raceway. What my point is, using a peice of conduit for protection and stubbing it into a wall or into a floor does not make it a raceway, therefore, the securing and supporting of the cable must be conformed to. So the point is not how supported or secured the cable is , the point it is what you are calling a raceway.
 
B

bphgravity

Senior Member
Location
Florida
Re: NM cable in EMT

Post Script, the code says "protected by conduit" not protected by a raceway. Conduit may be used as a raceay, but by itself it is not.
 
don_resqcapt19

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Re: NM cable in EMT

Bob,
I personally don't see anything wrong with the practice, I just see it as a code violation. I think that Charlie Trout, also said in one of the NECA-NEIS code question of the day answers that NM cannot be installed in a raceway.
Don
 
roger

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
Re: NM cable in EMT

Don, 334.15(b) does allow NM to be installed in listed surface metal or non metalic raceway, regardless of the "conduit as raceway" conversation here.

I still think if it were not allowed it would be specifically stated. I mean how many articles contain the term "shall not" or specifically address uses not permitted like 400.8(6).

Would you think this was an oversite or that as Tom said, it was never the intent, therefor not addressed one way or the other? Now are we reading the "not being allowed to run NM in conduit" into the article because some others have published their oppinions.

Roger
 
L

larry dimock

Member
Location
Washington
Re: NM cable in EMT

I'm not intending to change the subject, but if you do judge that it's OK to run NM or UF in any conduit, remember that the conduit-fill limitations will apply, especially to conduit lengths over 2 feet. Are you really going to stick with code and use 3/4" or even 1" conduit for a single 12-2NM? There is an NEC section about calculating the fill based on the LONG width of the cable. What is that for 12-2, 1/2"? 5/8"?
 
roger

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
Re: NM cable in EMT

Larry, that would be chapter 9 note (9). Thats a good point, why would this be mentioned if it were not allowed? This note has nothing to do with note (4).

CM, with enough lube and a tugger it's no problem :)

I really don't know why I'm arguing for this, I don't use NM except for temporary wiring. :roll:

Roger
 
H

hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
Re: NM cable in EMT

Mark:
Yes 90.4 does allow the AHJ to judge what is safe or not in a given siduation. But 90.5 tell him what he is allowed to change and what is not allowed to be changed! This is why these two articals are placed together...
 
D

dan19403

Member
Location
Pennsylvania
Re: NM cable in EMT

Originally posted by goldstar:
Bphgravity,

:eek: I do not think or have ever thought that you or anyone in this forum has come off as being rude nor would I expect that anyone would think that of me. This is a great place to have these discussions whether we are right or wrong about the topics we discuss. The great thing about this forum is that you can usually get some great answers to specific situations within a 24 hour period and from rather knowledgeable people.

Anyway, back to supporting NM cable. If you sleeve NM cable inside a length of EMT for protection in an unfinished area and use a "from-to" connector like the one Iwire posted, as long as you have the EMT properly supported to the wall why should there be an issue as to whether the NM cable is properly supported ? Wouldn't you consider this done in a neat and workmanlike manner ?

With respect to ty-wraps, why do they make them ? Aren't you supposed to be able to ty-wrap cables together ? Are they made only for control panel bundling of wires ? If I had a straight NM cable run of about 50' and realized that I had to make another 50' run, would it be wrong of me to ty-wrap another NM cable to the one I just stapled to a joist or should I staple the new NM cable over the one I just ran ?

The AC contractor runs his condenser lines out the side of the house and down to the compressor. He wraps the condenser lines in Armor-flex and ty-wraps them together along with the control wiring from the blower unit. As long as the condenser lines are going to be enclosed in a piece of aluminum leader what would be wrong with ty-wraping a UF cable to the condenser line ? If he has to make a repair to the condenser line not only would he have to cut off my ty-wraps but his also.

Please tell me what you would do to make this installation correct.
Click to expand...
TO ANSWER THIS

With respect to ty-wraps, why do they make them ? Aren't you supposed to be able to ty-wrap cables together ? Are they made only for control panel bundling of wires ? If I had a straight NM cable run of about 50' and realized that I had to make another 50' run, would it be wrong of me to ty-wrap another NM cable to the one I just stapled to a joist or should I staple the new NM cable over the one I just ran ?


YES, IT WOULD BE ILLEGAL -- DON'T KNOW THE SECTION OFF THE TOP OF MY HEAD BUT YOU ARE NOT ALLOWED TO SECURE 1 CABLE TO ANOTHER CABLE -- EVEN THOUGH IT IS DONE ALL THE TIME
 
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