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#119137 - 12/07/04 06:42 PM Exposed NM Cable  
Admin  Offline

Joined: Oct 2000
Posts: 3,447
Here's some background. This panel is located in an open sided county fairgrounds building where 4H kids show sheep. Six feet to the left of the panel and you are out from underneath the roof. The white flecks to the left of the panel are staples with little "bits" of paper attached from kids (and probably adults) staple gunning posters, show schedules, etc. to the mounting board. This "rewire" was in response to my request that they repair 40+ year old NM that had significant damage to the sheathing.

To the electrician's credit, he also responded to a concern of the fair board of circuit breakers constantly tripping during the fair, because of overloaded circuits. So... his response was to put each receptacle on its own dedicated circuit. Hence... the massive number of wires coming out of the top of the panel.

I have continuing concerns about the adequacy of this installation. Here in lies the rub. I am an "OSHA" inspector (OK let's not get off topic here with OSHA bashing!) and this installation passed the electrical inspection. I'm not bashing the electrical inspector, because he works for the same agency I work for... but, I'm at a loss to explain how this would comply with the NEC as I understand the applicable sections. And to make it perfectly clear... I am aware that Article 334 allows NM to be installed in "exposed" work.

I don't want to taint anybody's opinion about what I think the violations are, I'd just like to know what the group thinks about this type of installation practice. Am I being too picky? This has ramifications beyond this particular building. I find similar installations frequently in the buildings I inspect. All of the buildings that I inspect are owned by the government (State, County, Local).

One of the other issues that comes up in the long run is... once an installation passes final, then the only (and I do mean only) person that might look at the equipment in the future is going to be someone in my position. The only other electrical inspection that ever happens in any building after a final is when there are significant alterations that require the pulling of a permit. Until that point, the installation can rot in place until a safety inspector happens to come by and finds an serious hazard that may have existed for an extended period of time.

OK. Enough of my soapbox background discussion. Comments? Ideas? Concerns?

- Glenn (safetygem)
[Linked Image]

Tools for Electricians:

#119138 - 12/07/04 09:59 PM Re: Exposed NM Cable  
John Steinke  Offline
Joined: Apr 2001
Posts: 518
Reno,Nv., USA
It seems that your primary concern is the use of NM in this location. I say, "not a problem." Maybe not my first choice, but not a violation.
One caveat: NM must be "protected" where "subject to damage." There also may be an issue over whether certain areas are "wet," as opposed to "damp."
Animals chewing on wire is a concern that would require some additional protection. Fertilizer and cleaning chemicals may eat up EMT, and movement (or the risk of a tractor banging into a pillar) might make NM an attractive choice.

#119139 - 12/07/04 10:42 PM Re: Exposed NM Cable  
electure  Offline

Joined: Dec 2000
Posts: 4,260
Fullerton, CA USA
"Six feet to the left of the panel and you are out from underneath the roof."
Would there be direct sunlight on this NM cable?

Would another concern for damage be the (what appears to me to be) PVc conduit coming in the bottom?

#119140 - 12/07/04 11:09 PM Re: Exposed NM Cable  
NORCAL  Offline
Joined: Sep 2002
Posts: 872
I see traces of rust on the panel which doesnt help the situation either.

#119141 - 12/08/04 02:15 AM Re: Exposed NM Cable  
frenchelectrican  Offline
Joined: Feb 2003
Posts: 939
Wi/ Paris France { France for ...
also i noticed something else about the type of wire it look like 12=3 NM cables and i did count the wire above the breaker box i came up 19 but look like they use mutli circuit set up and i am not too crazy with that.

i just cant find the other NM wire to verify it is full 40 circuit in 42 circuit box

but really if they run multi wire circuit they should use double pole breaker for good reason if they have junction box to split it off i think it will be wise idea to do that

merci, marc

Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)

#119142 - 12/08/04 09:29 AM Re: Exposed NM Cable  
dmattox  Offline
Joined: Oct 2004
Posts: 265
Anaheim, CA
I would consider that at a minimum to be a damp location and probably a wet location. 334.10(A)(1) NM is only allowed in dry locations, but I would be more concerned about the connectors they used. Looks like they are standard 2 screw connectors.

334.15(B) Requires protection from physical damage. If this doesn't need protection when would you? Someone might hit it with a pitchfork [Linked Image]

frenchelectrican, are you saying one needs to use a 2 pole breaker on all 12-3 runs, even if they are 2 separate circuits sharing a neutral?

#119143 - 12/08/04 06:20 PM Re: Exposed NM Cable  
iwire  Offline
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
As long as this is NM-C it is fine.

ARTICLE 547 Agricultural Buildings

547.5 Wiring Methods.

(A) Wiring Systems.
Types UF, NMC, copper SE cables, jacketed Type MC cable, rigid nonmetallic conduit, liquidtight flexible nonmetallic conduit, or other cables or raceways suitable for the location, with approved termination fittings, shall be the wiring methods employed. Article 398 and Article 502 wiring methods shall be permitted for areas described in 547.1(A).

I would be willing to bet NM has been used for years in these types of buildings.

The physical damage issue is entirely subjective and up to the inspector to decide.

ARTICLE 334 Nonmetallic-Sheathed Cable: Types NM, NMC, and NMS

334.15 Exposed Work.

In exposed work, except as provided in 300.11(A), the cable shall be installed as specified in 334.15(A) through (C).

(A) To Follow Surface. The cable shall closely follow the surface of the building finish or of running boards.

(B) Protection from Physical Damage. The cable shall be protected from physical damage where necessary by conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, pipe, guard strips, listed surface metal or nonmetallic raceway, or other means. Where passing through a floor, the cable shall be enclosed in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, listed surface metal or nonmetallic raceway, or other metal pipe extending at least 150 mm (6 in.) above the floor.

The inspectors in this area would pass this no problem it is neat, tight to the building surface and at least 6' off the floor.

Someone might hit it with a pitchfork

I think that is a big what if? [Linked Image]

IMO this is a code minimum installation, sure pipe would be better but not required

Bob Badger
Construction & Maintenance Electrician

#119144 - 12/08/04 07:11 PM Re: Exposed NM Cable  
dmattox  Offline
Joined: Oct 2004
Posts: 265
Anaheim, CA
The pitchfork comment was a joke btw [Linked Image]

Read on to:


547.5(C)(2) Damp or Wet Locations. In damp or wet locations, equipment enclosures, boxes, conduit bodies, and fittings shall be placed or equipped so as to prevent moisture from entering or accumulating within the enclosure, box, conduit body, or fitting. In wet locations, including normally dry or damp locations where surfaces are periodically wased or sprayed with water, boxes, conduit bodies, and fittings shall be listed for use in wet locations and equipment enclosures shall be weatherproof.

Near the edge of a barn would be a damp location to me. And it is probable that someone would use a hose to clean the facilty , least more so than in a house or office building. So IMO it should be weatherproof.

Put it this way, would you guys think this was ok outside a house under a patio cover? To me it seems to be a similar situation, and would never be allowed.

#119145 - 12/10/04 03:02 PM Re: Exposed NM Cable  
safetygem  Offline
Joined: Jan 2002
Posts: 119
Ohio, USA
Thanks for your comments. You have all addressed my basic concerns and seem to have validated my position. [Linked Image] Although it would appear that many of you feel that this would meet the mimimum installation requirements.

In addition to the potential violations each of you mentioned, I'd like to throw out two more. Because of the large number of public buildings where I find NM cable installed in exposed work... I decided to look up the NEMA installation information for NM. In the NEMA's "Application and Installation Guidelines for Nonmetallic-Sheathed Cables", it states that NM cable 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 rating." This requirement is mirrored in NEC 334.10(3).

Also, I would argue that following the NEMA document is a listing and labeling requirement, and therefore deviation is a violation of NEC Article 110.3(B).

You can download for free and read the NEMA application guidelines at:

Also, while we might call this building "agricultural", in reality, it is an assembly occupancy. It primarily houses people, who happen to bring along a few barnyard animals. The building is only used for one week out of the year, but, during that one week thousands of people may pass through while only a couple of dozen animals may be present. I have found people hanging equipment like fans, tools, and other miscellaneous things from NM. They must think this is plastic cable is a clothes line that they can use to hang things. [Linked Image] This (I believe) increases the likelihood of physical damage. And… regardless of whether this is an “agricultural”, “assembly”, or any other type of commercial occupancy… this is definitely not a “dwelling” and therefore I believe the NM must be concealed.

I’m always trying to keep a reasonable perspective when I conduct inspections and want to continue to learn about best practices. If you think I need to rethink my position... I'm always willing consider additional interpretations.

Thanks again for your comments. [Linked Image]

BTW, here is what I put in my original report. I could have "hung my hat" on any of the potential code sections mentioned in this thread, but, I decided to go with the physical damage issue:


Recommended Action: Have a qualified electrician repair, replace, or install the electrical equipment according to the instructions provided and in accordance with NFPA 70-2002, the National Electrical Code (NEC). Nonmetalic-Sheathed Cable (e.g., "Romex") must be installed in accordance with provisions of NEC Article 334. Paragraph 15(B) specifies requirements for its protection in "exposed work."

National Electrical Code, NFPA 70-2002 (Emphasis added)
Article 334 Nonmetallic-Sheathed Cable: Types NM, NMC, and NMS
334.15 Exposed Work.

(B) Protection from Physical Damage. The cable shall be protected from physical damage where necessary by conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetalic conduit, pipe, guard strips, listed surface metal or nonmetalic raceway, or other means. Where passing through a floor, the cable shall be enclosed in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetalic conduit, listed surface metal or nonmetalic raceway, or other metal pipe extending at least 150 mm (6 in.) above the floor.

While "physical damage" to insulation is not defined in the NEC, the NEC handbook has wording describing causes of insulation failure, "the principal causes of insulation failures are heat, moisture, dirt, and physical damage (abrasion or nicks) occurring during and after installation. Insulation can also fail due to chemical attack, sunlight, and excessive voltage stresses." It was noted during this visit that NM cable is located in various locations where the insulation could fail based on these exposures.

NOTE: The fundamental requirement to protect NM cable from physical damage has been in the NEC for more than 45 years. For example, NFPA 70-1959, Section 336-6. Exposed Work, "In exposed work, (b) It shall be protected from physical damage where necessary. " The NEC handbook from 1959 further describes the potential of damage to NM cable, "In northern climates where temperatures of 0 F or below are frequently experienced during the winter, the ordinary types of nonmetallic-sheathed cable, where installed in dairy barns and similar farm buildings, have in some cases deteriorated rapidly, due to the growth of fungus or mold inside the cable." While in several buildings, neoprene covered NM cable was found, several other buildings were still wired with older "Cresflex" type NM cable described in the handbook advisory. It is highly probable that this older wiring has significantly deteriorated and should be replaced as soon as possible and when rewired, the building conductors must be protected by conduit, preferably PVC.

You should have a person evaluate all older wiring according to the provisions of "The NETA Maintenance Testing Specifications." These specifications are written by the International Electrical Testing Association and the latest edition was published in 2001. It is available from NETA in 3 different formats. You can contact NETA on the World Wide web at: or by phone: 888-300-NETA (6382).

Edited to correct UBB code error.

[This message has been edited by safetygem (edited 12-10-2004).]

#119146 - 12/10/04 08:55 PM Re: Exposed NM Cable  
OreElect  Offline
Joined: Mar 2004
Posts: 98
Amendment for 334.15(B)Exposed nm shall be protected where it is installed horizontally below 8 feet above the floor that enters the top or bottom of the panelboard shall be protected from physical damage by conduit,1/2 plywood or 1/2 drywall.

That would not fly here.

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