NM cable in EMT

[iwire]

Re: NM cable in EMT

Wow, this post has gone a lot of places, here is the original post

Posted By MarkF

Here's an old question that has been around for years. We are installing alot of air conditioner circuits for a local AC contractor. Most of the time we are able to get the circuit through the basement directly to the back of the disconnect. However, there are times that we have to run an additional 10-30 feet on the outside of the house. The local AHJ has demanded that we install a j-box on the outside and convert to THWN conductors. He has admitted that this is not in the code book (NEC) but he read an article on it and the writer "suggested" that NM not be run in conduit because it is not Wet of damp location rated.

Has anyone run into this before? I have been an electrician since 1973 and this is a first for me.

Thanks for your comments

Mark

I would have to agree this would be a wet or damp location, I have not found raceways to stay dry when outside, no matter how carefully installed.

As to running NM or UF in EMT

NEC 2002 358.22 "Cables Shall be permitted to be installed where such use is permitted by there respective code articles"

340.10(4) When installed as Non metallic sheathed cable....shall comply with article 334

334.15(B)Protection from physical damage.

IMO to be code compliant all you have to do is say "I am protecting it from physical damage"

Certainly that was what the original post was doing and that would be what I do when I come down the surface of a wall down to a outlet.

I do not think anyone wants to run NM or UF in raceways or sleeves just for the fun of it.

334.15(B) does not say a maximum length that you can do this.

I hope they make this more clear in 2005 as it was clear in the 1999 book.

 

[bphgravity]

Re: NM cable in EMT

Dan, I believe there are two ways to interprete the NEC. One way is what I call LOOSE INTERPRETATION. This philosophy believes that if the code does not specifically say it shall not be done, than it is allowed. The other way is STRICT INTERPRETATION. This philosophy believes that if the code does not speciffically say it shall be done, than it can not be done. Some people read the code looking for restriction on the installation, some read it to find the allowances. Its a fine line. In most cases, as an installer, you are trying to find every possible way to do a job in a safe, high quality, and productive manner. As an instructor or AHJ, you are more interested in the actual NEC word for word. When I give my continuing education courses or teach for the apprenticeship program, these students are required to know exactly what the code requires, because that is what is on electrical exams, and this is what AHJ enforce. I then continue to encourage looking at code as a startng point and to always work above it. I never suggest or even hint that you can "beat the code", or "find a loophole" because the code is unclear or an error was made from edition to edition. So for example, I can tell you that 300.11(C) prevents you from suporting cables from other cables by means of a "tie-wrap". This is what I have to teach my students. Now as a contractor, I may feel that using tie-wraps in this manner is just as effective as straps or staples, and practice these methods. I can go on to argue that "tie-wraps" are not listed for use as support, but for a means to bundle. We can go on and on. This is why I stated twice in this one topic that it really comes down to the local AHJ. Many of my posts are not directed to the several memebers of this forum that certainly don't need my input or education. They are really for the untrained and uneducated that are coming to this forum to learn something completely new and to locate something in the code thay never looked at before. I feel it is important to be careful not to provide information to these persons that is not completely accurate. Other times, I am simply trying to inspire conversation and discussion about an issue. I really do not see a major safety concern with this topic and feel that the effort that has been put into this topic would have been better spent elswhere on more important issues, so I will leave it at that. Thanks for your time.

 

[mikeackley]

Re: NM cable in EMT

I have a curiosity question related to this topic ? my actual experience with residential/NM cable is limited. As I read 334.15(B) ? Protection from Physical Damage, listed are all the various raceways types permitted to protect NM cable. In there I find the words "...listed surface metal or nonmetallic raceway, or other metal pipe..." Wow, on the surface that appears to be most liberal. Does this really mean that one is permitted to sleeve NM-B where passing through a floor with a chunk of water pipe???

[ April 10, 2003, 10:55 AM: Message edited by: mikeackley ]