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I'm thinking about installing a new circuit. The panel is on the wall in an unfinished basement. Three questions:

  1. Is the new NM cable going down to and around the panel considered to be "subject to physical damage" (300.4) so it must be protected as described in 334.15(B)?

  2. Does the matter whether the cables are above, below, or on the side of the panel, or how high up it is?

  3. If protection is required, should I sleeve them in EMT up to the floor joist cavity? Are there other solutions that are practical?

I'm in Massachusetts, so NEC 2014 applies with these amendments. After much digging, I haven't found anything explicit in the code. But I'd like to know not only what the NEC will let me get away with, but also what is sensible and good workmanship. I wish I could look at what's already there for guidance, but it looks like this … at least I would like the new work to be done properly.

panel

I'm unsure about how to interpret the following from 334.15(C):

Nonmetallic-sheathed cable installed on the wall of an unfinished basement shall be permitted to be installed in a listed conduit or tubing or shall be protected in accordance with 300.4. Conduit or tubing shall be provided with a suitable insulating bushing or adapter at the point the cable enters the raceway.

Does this mean that if you have NM on the wall in an unfinished basement, then it is considered to be subject to physical damage, and you must put it in listed conduit or tubing unless it is already protected as described in 300.4 (none of which seem relevant, especially since the Massachusetts amendments delete 300.4(D))? Or can it still be unprotected if it is somewhere that is not subject to physical damage (however that is decided)?

Relevant articles in NEC 2014:

300.4 Protection Against Physical Damage. Where subject to physical damage, conductors, raceways, and cables shall be protected. [Goes on with details about going though wood members, though metal members, behind removable panels, parallel to framing members and furring strips, in or under roof decking, in shallow grooves, in insulated fittings, and crossing structural joints.]

334.10 Uses Permitted. Type NM, Type NMC, and Type NMS cables shall be permitted to be used in the following except as prohibited in 334.12 [which does not seem to contain anything relevant]: (1) One- and two-family dwellings and their attached or detached garages, and their storage buildings. […] 

(A) Type NM. Type NM cable shall be permitted as follows: (1) For both exposed and concealed work in normally dry locations except as prohibited in 334.10(3) [which is irrelevant, because my house falls under 334.10(1)]. […] 

334.15 Exposed work. In exposed work, except as provided in 100.11(A), cable shall be installed as specified in 334.15(A) through (C).

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

(B) Protection from Physical Damaga. Cable shall be protected from physical damage where necessary by rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, Type RTRC marked with the suffic -XW, or other approved means. […] 

(C) In Unfinished Basements and Crawl Spaces. Where cable is run at angles with joists in unfinished basements and crawl spaces, it shall be permissible to secure cables not smaller than two AWG or three 8 AWG conductors directly to the lower edges of the joists. Smaller cables shall be run either through bored holes in joists or on running boards. Nonmetallic-sheathed cable installed on the wall of an unfinished basement shall be permitted to be installed in a listed conduit or tubing or shall be protected in accordance with 300.4. Conduit or tubing shall be provided with a suitable insulating bushing or adapter at the point the cable enters the raceway. The sheath of the nonmetallic-sheathed cable shall extend through the conduit or tubing and into the outlet or device box not less than 6 mm (1/4 in). The cable shall be secured within 300 mm (12 in) of the point where the cable enters the conduit or tubing. Metal conduit, tubing, and metal outlet boxes shall be connected to an equipment grounding connector complying with the provisions of 250.86 and 250.148.

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    In my area it only has to be protected in a finished area. I am going off inspectors (who use NEC 2011... kind of) wants. I am sure there are other interpretations though.
    – DMoore
    Commented Apr 9, 2014 at 18:45
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    So in an unfinished area you're not expected to protect at all? My work won't be inspected, so I don't have an inspector's interpretation to go by.
    – Vebjorn Ljosa
    Commented Apr 9, 2014 at 18:48
  • NM cable has to be protected on a wall in both finished and unfinished locations. However, I think there's a loophole, since the wiring is fastened to the plywood. I'm not exactly sure of the code section that covers this, but it's fairly common practice.
    – Tester101
    Commented Apr 10, 2014 at 17:16
  • I am pretty sure that this depends on the local code but, generally, it is OK to leave exposed Romex in unfinished (exposed framing) areas. On a separate note, you don't get to see very many stone walls in the U.S. these days. It's pretty awesome. What year is the house?
    – amphibient
    Commented Apr 10, 2014 at 20:27
  • Thanks.The house is from the 1880s. It's nothing special here in Massachusetts. And there is nothing awesome about a fieldstone foundation: it's messy and leaky.
    – Vebjorn Ljosa
    Commented Apr 10, 2014 at 21:23

2 Answers 2

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It's definitely a interpretation issue with the local inspectors. You can improve the installation in the picture by following the guidelines in 110.26 they may allow the wire within the working space about the panel to be not subject to damage but the water line should be rerouted to be outside the working space described in 110.26 also the wire should be supported per 334.30.

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What I would do, and I’m not kidding, I would find a large, nearby housing development, where they are currently building homes and pretend I’m interested in buying and have look at some samples. Hopefully the electrical services are in the basements and they’re unfinished. Study how the wires are installed for everything down there sump pump receptacles, HVAC equipment, everything and then you’ll know. What you’ll most likely be looking at is a no frills installation, just enough to be approved, no less and no more.

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    If you did that, I would wear a disguise.
    – DMoore
    Commented Apr 12, 2014 at 4:46

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