6

I have built a steel garage kit. All my horizontal NM runs are 9 1/2 feet high, fully secured (with closer spacing than code requires), and where needed I added pieces of steel studs to provide secure attachment and protection. Of 550 feet of NM cabling there is literally just a few inches that are not immediately adjacent to a piece of steel. The problem is the nebulous wording of NFPA 70 334.15(B) "Cable shall be protected from physical damage where necessary....."

In various posts/articles across the web (including this forum) people make statements similar to "wiring over 8 feet is considered protected" yet I can find no explicit statement in the code nor does any writer quote a reference to any such rule. Is there any such code/rule? My inspector says I have to construct coverings over all my horizontal runs - wood or plywood or drywall - to give them 'protection'. Almost 10 feet up in the air. Clearly absurd but I am not sure what the rational rebuttal is. Any suggestions would be appreciated.

Update: should have mentioned, state is CA. I found a document that seems to list all CA modifications to NEC, scanned that but did not see anything relevant. The primary special feature was that I ran oversized conduit to the subpanel and left 2 breaker positions open, so someone someday can pull a bigger feed for a car charger. They like that kind of stuff out here.

Success!! Inspector came today but was not the previous one who is still (I think) officially assigned my permit. Anyway, I had articles printed out as mentioned below, we had an intelligent discussion (which did not seem possible with the other one). Contractors typically put up (unpainted) drywall in garages around here so possibly these guys do not deal with exposed NM much, who can say. But he agreed no mechanical protection needed for NM over 8 ft in the air. Whoopee! Thanks for the extra code reference, I figured the 8 ft number was coming from somewhere.

2
  • ";Where necessary" is not defined in the NEC, has the state or local authority adopted amendments to the NEC? – NoSparksPlease Jul 21 '20 at 13:13
  • 2
    It sounds like you have an inspector that doesn’t like homeowners doing there own work. I have run into this when remodeling a vacation home I owned in a different county than I normally work and when I moved to my current location. I let the inspector feel all important write everything up then ask for the code reference ). most states require the inspector to cite the code reference to write a violation) when they cannot ask them to approve the job on the card or whaT method they use. Next call the chief electrical inspector and lodge a complaint. Until more folks do this it will continue. – Ed Beal Jul 21 '20 at 14:28
1

Voltage application of 8’ is considered protected by elevation. infact live parts can be considered protected above 8’ 50-300v. 8’7” is good for 1000v these are live parts see NEC 110.27.

Beyond that ask the inspector to cite the code reference.

There is no code reference that states all horizontal runs require protection.

Look at the code for a crawl space or a basement attic both are horizontal runs that usually are below 8’ and permitted on surface runs per NEC 334.15.

The exact height for protection from physical damage is not listed and I have provided multiple examples where protection by elevation is allowed and exposed nmb is allowed below the height you have.

3
  • This is helpful. I can start a discussion with these points. But 110.27(B) also talks about preventing physical damage, and does not seem to be exclusive vs. (A)(4). The inspector has unique ideas about how/where damage 'might' come from. – 4thGenCarpenter Jul 21 '20 at 15:33
  • It suggests for live conductors these are not covered wires these are open buss bars for example on equipment , they are quit common on gantry cranes open 480 bars live yes. Again ask her to cite the code reference unless a local code there is not one. – Ed Beal Jul 21 '20 at 15:41
  • 1
    Physical damage is what the inspector is trying to cite 334.15.B protection from physical damage when required, then refers to 300.4 protection from physical damage where subject to physical damage conductors raceways and cables shall be protected. We can keep on going I can show many similar statements but above 8’ even live parts do not have to be guarded from accidental contact because they are not subject to damage , contact because of height. As I said I would push this one inspectors can be jerks but some are really nice and helpful you got the jerk, unless code changed in Ca. – Ed Beal Jul 21 '20 at 17:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.