grounding with brass screws

[jb64]

I am an electro-mechanical technician who builds and wires industrial assembly machinery. Recently, I was told that when I install the ground lug on the power panel that I am required to use a brass screw. Also I scrape the paint off of the panel so that the ground lug is against the bare metal. This same person says that is unnecessary as the screw makes the ground. I disagree with him but I have found nothing in the NEC to affirm or refute my position. Is my colleague right?

 

[Jim W in Tampa]

Re: grounding with brass screws

I am an electro-mechanical technician who builds and wires industrial assembly machinery. Recently, I was told that when I install the ground lug on the power panel that I am required to use a brass screw. Also I scrape the paint off of the panel so that the ground lug is against the bare metal. This same person says that is unnecessary as the screw makes the ground. I disagree with him but I have found nothing in the NEC to affirm or refute my position. Is my colleague right?

On scraping part yes but know of no reason for brass screws.

 

[winnie]

See NEC 250.12 This is generally read as requiring the removal of paint from _contact surfaces_, or require the use of fittings that make the removal of paint unnecessary.

A common fitting used to make paint scraping unnecessary is a 'paint piercing grounding washer'.

Most 'grounding screws' (eg. those used in junction boxes) are simply green screws with a head that grips wire well, probably steel.

-Jon

 

[dlhoule]

Re: grounding with brass screws

I am an electro-mechanical technician who builds and wires industrial assembly machinery. Recently, I was told that when I install the ground lug on the power panel that I am required to use a brass screw. Also I scrape the paint off of the panel so that the ground lug is against the bare metal. This same person says that is unnecessary as the screw makes the ground. I disagree with him but I have found nothing in the NEC to affirm or refute my position. Is my colleague right?

On scraping part yes but know of no reason for brass screws.

I think Jim meant you are right on scraping part; not your colleague.

I also agree with Jon on 250.12. And if you are not tapping that hole there is absolutely no doubt about it: unless using fitting designed for the purpose you must scrape the paint.

 

[iwire]

Re: grounding with brass screws

I am an electro-mechanical technician who builds and wires industrial assembly machinery.

The NEC may not apply.

It sounds like NFPA 79 Electrical Standard for Industrial Machinery would be the correct standard.

 

[paul]

Re: grounding with brass screws

The NEC may not apply.

It sounds like NFPA 79 Electrical Standard for Industrial Machinery would be the correct standard.

I was thinking along the same lines.