Uses not permitted.

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mjf said:
Think warehouse as opposed to residential garage.
Think forklift as opposed to HO step ladder.
Think RMC as opposed to EMT.
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I agree but IMO an authority having jurisdiction can make that call since there is no definition of severe other than the dictionary
 
I'm going to repeat a theory of min on that no on ever seems to understand or agree with.

I assert: It is perfectly proper to take direct experience - the history of a specific job - into consideration when deciding what is an acceptable wiring method. Evidence of damage is enough to invoke the Article 110 requirements for mechanical and corrosion protection, enough to require additional protection.

For example: I once saw EMT run in a groove in a busy commercial driveway. Was EMT allowed for this use? Well, as an existing installation, one could easily see that the pipe was not harmed at all by the heavy truck traffic that crossed over it.

Another example: I saw an industrial plant where a particular section of RMC would be damaged if/when the product jumped off the conveyor. The plant addressed this by passing the conduit through a section of structural tubing for the few feet where this might happen. Perfectly proper IMO.

"Severe damage" is not specifically defined by the NEC, nor is "likely." That's what dictionaries are for.

Let's imagine a receptacle mounted to a column. I'd say that if it was mounted on a face where traffic could strike it, you can require it to be protected. I've seen them protected by placing them on another face of the column, and I've seen them protected by welding stout 'ears' around them.

It comes down to good design. Good design meets code - but the opposite is not always true. Indeed, using the NEC as your design guide often nds in a poor design- and a code violation anyway. How else can we have this conundrum where an Article 300 "permitted" method is seen as being in conflict with Article 110?
 
So...
1) There is no specific to the NEC, usable definition
2) Common sense, opinion, and best guess apply
3) We are at the mercy of the AHJ if it is not obvious


I do not have an actual situation, I was answering a question about if nail plates were needed for EMT in wood studs and I noticed this. It is my opinion this should be a bit more clearly defined. I am certain everyone here could come up with heavy commercial/industrial applications where it would not be such a far stretch to say it is more than probable severe damage may occur but EMT is not at all a violation. Hmm...
 
captainwireman said:
So...
1) There is no specific to the NEC, usable definition
2) Common sense, opinion, and best guess apply
3) We are at the mercy of the AHJ if it is not obvious


I do not have an actual situation, I was answering a question about if nail plates were needed for EMT in wood studs and I noticed this. It is my opinion this should be a bit more clearly defined. I am certain everyone here could come up with heavy commercial/industrial applications where it would not be such a far stretch to say it is more than probable severe damage may occur but EMT is not at all a violation. Hmm...
Click to expand...

It is a judgement call. Considering the ease of installation of nail plates, if I had a doubt I would bang them up where needed. There is nothing wrong with going above and beyond the NEC.
 
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