Scraping Paint Code?

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whiplash68

New member
Hello,

New member here. Our Company is an OEM for the water/wastewater industry. We also design and build our own control Systems and panels. Our panel shop is UL-508A approved.

I?m not sure if this is the right forum but I have an ongoing issue with our shop foreman regarding the service ground lug of control panels. He currently taps and bolts the ground lug right on the painted back panel (next to the service main breaker). I finally noticed he doesn?t (and learned he never has) scraped or grinds the paint off the back panel prior. To me it seems like common sense which is why I never took notice.

I am looking for documentation in the NEC and/or UL that is specific to control panel grounding. I do see some articles referencing the NEC 250-96 but this seems to be regarding conduit grounding and not necessarily industrial control panel service power grounding.

Any help on this would be greatly appreciated.

Thanks!
Steve
 

kwired

Electron manager
Location
NE Nebraska
Last part of 250.12

or be connected by means of fittings designed so as to make such removal unnecessary
.

Using certain washers may not require removal of paint.

What is the thickness and number of threads engaged in the tapped hole? IIRC there is a point where this would be acceptable and no paint removal is necessary.

You did mention that you are a UL shop. I don't know what rules you have to follow but do know that you do not always need to follow NEC.
 
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Rockyd

Senior Member
Location
Nevada
Occupation
Retired after 40 years as an electrician.
Last part of 250.12

.

Using certain washers may not require removal of paint.

What is the thickness and number of threads engaged in the tapped hole? IIRC there is a point where this would be acceptable and no paint removal is necessary.

You did mention that you are a UL shop. I don't know what rules you have to follow but do know that you do not always need to follow NEC.

250.8(A)(5) & (6) is the verbiage I believe you're looking for.
 

Rockyd

Senior Member
Location
Nevada
Occupation
Retired after 40 years as an electrician.
Is that some prehistoric life form?:)

If I recall correctly isn't it in the UL as IEEE as KDER 514 B? Someone with the correct books will have the answer for you...I just do NEC for the most part.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I don't believe it is required by UL at all. The threads provide adequate engagement especially with the correct washer. Grinding the paint is unnecessary IMO.

The word "paint" does not appear in the UL508a standard.
 

mbeatty

Senior Member
Location
Illinois
The only requirements I could find state that there must be an effective ground fault path. We use the external toothed washers to ensure a good ground connection.
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
250.12 Clean Surfaces.
Nonconductive coatings (such as paint, lacquer, and enamel) on equipment to be grounded shall be removed from threads and other contact surfaces to ensure good electrical continuity or be connected by means of fittings
designed so as to make such removal unnecessary.
 
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