The shop building on a property I want to buy was built in 2005 but not wired until 2006. The building is metal with a wood framed interior office and bathroom.

It appears to be wired with Romex and has been carefully structured with the outlets at the 5' high purlin. All of the other runs are taken up to the 10' or higher to go across and appear to be captured with clamps or plastic ties to the metal structure and protected by the material similar to running down a wood post, etc. The load balance appears to be ok, with separate circuits for the items that require them, etc.

On the area above the office, the wires are stapled to the floor along the steel wall, but the floor is storage area.

Is this an acceptable situation for an outbuilding of this type? Does it matter whether or not the proposed use of the building is as a shop, or for storage, or for animals or a combination thereof?

I am wondering what would be necessary to fix it if it is not ok for some identified use. For example, could the romex be rerun in plastic conduit or raceways anything like that to make it acceptable if it is not ok as is.

Update: I am so sorry I left this info off - this is an outbuilding on an acreage with a separate house with attached garage, not commercial. This building is a playroom/shop/horse stable/whatever building. I don't know exactly how it will be used yet. I expect that the building is not to code, but I don't know. It looks like someone tried pretty hard to get it right. No one seems to know who did the work, nor how many owners ago. The building has water, electrical 125 amp service panel tied to the main house (outside of the house not in its panel. There is a breaker in the panel for the house and another for this special use building, both served by the same meter although separate meters could be installed easily. The building has a concrete foundation with water and sewer plumbing installed in the floor. It is not insulated except the office and bathroom 20 x 8 is insulated, heated with space heater and air conditioned. It also has a water heater (small)).

  • The romex should protected up to 8'. Are there perminant stairs to the storage upstairs? If so the wiring needs protection on the floor and up to 7'
    – Ed Beal
    Jul 12 '18 at 17:04
  • Does running the wire inside an upright C-purlin qualify as protected? The C purlins are open side of the C facing upwards and the cable is laying in it for about 8 to 10 ft with cable ties holding them together, but nothing to the structure otherwise.
    – JayDubyah
    Jul 12 '18 at 17:22
  • In order to protect the nm I would have to disconnect and string the NM through an 8' or longer conduit of metal or sch 80 pvc conduit above the first cable clamp above the outlet, right? Or do they have to be conduit from the box up with appropriate boxes and fittings? I need to determine how much has to be done before I proceed. I know the inspector will have the final say, but I don't want to under estimate and then have offered too much.
    – JayDubyah
    Jul 12 '18 at 17:31
  • It also looks like a 30 amp run has an outside outlet that has rigid sch 80 conduit to the outdoor box but it only goes to the floor of the storage loft area. Then it is run along the steel girder to the other wall and along the C purlin to the wall where the box is located then down without protection inside the opening between the wall and the C-purlin. There are permanent steps starting at about 4 ft with movable lower steps with 13" rise - almost two steps at once
    – JayDubyah
    Jul 12 '18 at 17:36
  • I will assume that the stairs will be considered permanent. The wires should have been protected.
    – JayDubyah
    Jul 12 '18 at 17:41

Determining whether NM cabling is permissible can be surprisingly difficult.

In my opinion, if this is an outbuilding to a residence, it's cut and dried:

334.10 Uses Permitted. Type NM, Type NMC, and Type NMS cables shall be permitted to be used in the following:

(1) One- and two-family dwellings and their attached or detached garages, and their storage buildings.

As long as you don't go afoul of 334.12 Uses Not Permitted (service conductors, embed in concrete, wet locations, etc.) NM is OK for single family dwellings, garages, outbuildings.

However, in reality there can be complications. Again in my opinion there should not be in this simple case, but often there are complications, disputes, disagreements, etc. For other than single family dwellings / outbuildings, the actual rules are convoluted involving building code construction type classifications, occupancy classifications, and the NEC. Electricians, engineers, architects, and inspectors trip up on and argue over this stuff all the time.

In your situation, my concerns would be

  • safety
  • issues with buyer's inspection when you sell in the future

With respect to safety, properly installed, NM in a metal building is code compliant and generally safe, there's no reason for concern just because there's NM. If it isn't installed in a manner such that it's protected from the sharp edges of the metal, that can be a concern. The stuff that's stapled to the floor that's being used for storage sounds like a legitimate concern, but should be fairly easy to correct.

With respect to a future sale, since the NM is code compliant, you shouldn't have to worry about much. You only have to worry about a future home inspector, working for a prospective buyer, that doesn't understand the rules. The buyer's home inspector may think NM is not permitted in metal buildings and put that on his inspection report for the buyer.

If that happens, you can only try to refute the buyer's inspection report. You could show them the applicable code section. You could have your own inspector or engineer write up a formal report explaining why NM is OK. You also may be able to refer to the permit and inspection records for the property with the local code enforcement.


The shop building on a property I want to buy was built in 2005 but not wired until 2006. The building is metal with a wood framed interior office and bathroom.

So I am assuming this building is a commercial building. What does the AHJ have to say about and what does the municipality say about how this property is zoned and classified. 2006 was 12 years ago and things can change in that time. the NEC has had 4 revisions but I don't think this is a code question.

There are certain commercial property classifications that allowed romex and there are municipalities that allow those type of buildings in certain zones. So run it by them and see what they have to say.

  • I suspect outbuildings to a single-family dwelling unit would not be considered "commercial buildings" by any sane AHJ, but I'm not sure what the OP's situation is, either... Jul 12 '18 at 23:04
  • Yes it is residential, please see update - so sorry for not including info.
    – JayDubyah
    Jul 13 '18 at 21:50
  • I was hoping to be somewhat enlightened when my inspection report comes back so that I know what to look for and how much I should anticipate is required to bring it up to 'legal' status (I will want to sell again someday.)
    – JayDubyah
    Jul 13 '18 at 21:52

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