ECN Forum Forums Code Related Discussion NEC & other Code issues EGC attachment

I think that is pretty clear that paint needs to be removed.... Outdoor grey painted panels will have paint also in any hole for grounding or bonding meathod. Short of re-painting the surface, after contact is made,(which I think is a bad idea... see 110.12(C)) something like NOAL-OX, Zinc paste or the stuff I posted a picture of to protect against corrosion on the electrical connection is required, depending on environment. IMO If in an indoor panel, I think its a non-issue... Outdoor panel in salt air, different story.


Either way, I think a treaded connection in a thin can for a large lug w/ a large conductor like a bonding jumper is not mechanically strong enough for the purpose. And personally tend not to even trust the connection provided with panels connected by a 10/32. I don't know my own strength and tend to over-torque them...

Earl, the more correct question would be "what section prohibits it?" the NEC is a permissive code.

That is what you should do, so how do you ignore 250.12?



Now, if the fitting is designed to penetrate the paint then the finish is compromised anyways isn't it, so what happens to 300.6 now?


You can not eliminate one requirement for another.

If the enclosure is soley protected by enamel, you would be with in your rights to have the installer paint over this area after the lug, bar, or what have you is installed.

90.4 obligates you to enforce all the code, it doesn't allow you to ignore sections of it or add to it.


Roger



[This message has been edited by Roger (edited 11-20-2005).]

I am not ignoring or adding to the code. In my opinion, the attachment of a lug to the thin metal of an enclosure like a panel box cannot be made securly enough to provide a low impedance grounding path. In my small area of jurisdiction, my opinion counts to the degree as already discussed. In another inspector's opinion this grounding method may be OK, I don't know. I could have my opinion changed by evidence to the contrary, but I don't see such evidence presented here, only opinions.

I will say this: I have approved using grounding clamps to building steel (a much thicker metal) by using the method you have described. Threaded holes (with at least two complete threads) or bored holes using corrosion resistant bolts with locknuts are OK with me, so long as the paint is removed, and the metal is protected from corrosion afterwards.

earlydean,
So I assume that you do not permit the use of listed equipment grounding bars. Their only connection to the panel is the threads of the two 10-32 screws. A lug bolted on to a clean (bare metal) would have less impedance than the listed ground bar.
Don

Don,

Of course I would accept a listed ground bar installed in accordance with that listing. I have stated I would already. Listed assemblies have been tested for their effectiveness.
110.3 contains the rules I must follow.
Please note as well 110.2 which gives the AHJ the authority to judge what is acceptable or is not.

My point is that a lug bolted to the bare surface of the panel would be a far superior connection than that provided by the two 10-32 screws that provide the current path for the listed equipment grounding bus.
Don

110.2 is aimed at the AHJ, I do not know who the AHJ is in CT but I will be surprised if each local inspector is in fact the AHJ.

I imagine like MA that would be the State.

By the way along with MA and RI I am also licensed in CT. I had to take a separate code update for my CT license, what a pain.

Bob

E57 agan are yu saying a tapped hole is not a good electrical connection and what code reference do you make not allowing a tapped hole as long as not a sheet metal screw. Why do you insist on violating 300.6.

Early:

Again you are ignoring the manufactures instructions and UL listing. The manufacture provides you with tapped holes for both the ground bar and bonding the neutral. The instructions do not instruct you to sand the panel. In fact in a discussion I had with a Hoffman Engineer he explained to me that they had a grounding kit and that if sanding of the paint were done then the warranty would be null and void.

Rescapt:

Not necessarily. I just had a transformer that was installed 2 years ago and we relocated it. I noticed where the inspector at the time had required gouging the crap out of my electrical equipment had been done that rust had built up. Surely, you would admit that when the electrical panel rusts out around a bonding connection you have defeated the simple defination of bonding. Perminent. It does not say perminent until it rusts out.