ECN Forum Forums Photo Discussion Forums Photos for General Discussion Exposed NM Cable

1/2" plywood over the NM Cable would appear to an exhibitor a fine place to drive a nail to put up a flyer.

I think to cite the physical damage aspect of the NM cable without also including the physical damage aspect of PVC40 conduit would be a half measure.

NEC352.12 - Rigid Nonmetallic Conduit, "Uses not Permitted"....
"(C) Physical Damage. Where subject to physical damage unless identified for such use."

NEC352.10, "Uses Permitted"
(F) Exposed. For exposed work where not subject to physical damage if identified for such use.

Unless it's PVC80 it's a violation, & it looks like that feeder has an even better chance of getting clobbered than the Romex.

Arround here,for protection ,they would want it either boxed ,such as a stud space,below and on top to the 8',then covered with plywood or wall board or when using rnc,it must be sch 80.

Nema Standards Publication RV 2-2004
Application and Installation Guidelines for Nonmetallic-Sheathed Cables

"Currently, Types NMC and NMS are not commercially available, but Type UF-B can be substituted for NMC."

It does not say that NM-B is restricted to dwellings. What is does say has me a little confused, as this information is not in the NEC. Remember this document is not adopted by all jurisdictions, so is not necessarily enforceable.

"Use of Type NM-B in multifamily and other structures is restricted to buildings of 5 stories or less."

"Nonmetallic-Sheathed Cable, when used in Structures other than dwellings, must be concealed within walls, floors, or ceilings that provide a thermal barrier of material that has at least a 15-minute finish irating. as identified in listings of fire resistance rated assemblies."

As an inspector, this document provides some interesting information, but I would be hard pressed to say that in a commercial installation I would not allow NM cable to be installed exposed where it is protected from physical damage - whatever physical damage may be.

For anyone interested, read the disclaimer that is provided with this document.

Pierre

PCBelarge wrote:

I could have used one of the other NEC standards, but, chose to go with the physical damage issue. But, it probably would have been better to approach it from the perspective of 110.3.

Or I could have used 334.10(3). Which is identical to the information in the NEMA publication.

The NEC handbook provides a better description of the building types than Annex E.


The building in question here (wooden barn) is obviously in the Types III, IV, V category (more than likely Type V). So... Both the NEMA publication and the NEC seem to be in sync. They both allow NM cable in buildings other than dwellings. But, the difference is... in dwellings it can be installed exposed, but, in "other than dwelling units" that are not constructed of "non-combustible" material... it would seem NM has to be concealed. This is not what I see as I do inspections.

So... Glenn confused!

Personally, I don't see why there is a "lower" standard for dwelling units. I think it should be concealed everywhere unless the "exposed" NM is in an unoccupied attic or crawlspace. Which would essentially mean that it is "concealed" for all practical purposes.

Sometimes (like in this case) I am trying to figure out where the NEC language came from... which in this circumstance is obviously NEMA. Or maybe this is a chicken and egg scenario.

Edited for spelling errors. I guess that’s what happens when you are typing fast.

[This message has been edited by safetygem (edited 12-13-2004).]

Not that I didn't have enough information in my last post... but... I almost forgot to thank electure!

electure wrote:

Thanks! Sometimes I get caught up in the moment when doing an inspection and miss some obvious things!

I'll address the next time I go out to the site.

I'll go with iWire on the NM-C.