Screw Type Main Bonding Jumper

[hill900505]

Hey everyone,
I got a question about a service disconnect panel with the grounded conductors bonded to the enclosure using a green screw provided.
A separate EGC grounding bar is bolted in the enclosure.My confusion is that the main bonding jumper connects grounded conductor, EGC and service disconnect enclosure together. Since the grounded conductor is connected to enclosure by the green screw. The EGC bus bar is connected to the enclosure(bolted together). Is it legal to use the enclosure as the bonding path between the EGC bus bar and the neutral bar? I know it is a common practice but wouldn't the paint affect the bonding path? Also, sometimes the enclosure comes with a strap instead of a screw, do we treat this strap the same as a screw?

 

[augie47]

That is pretty much the "standard" for panels and both the factory "green screw" or strap is considered an adequate main bonding jumper.
There is no problem connecting your equipment grounding conductors to the ground bar attached to the cabinet.

 

[kwired]

If you were to install your own bonding jumper, removing paint at contact points would be necessary. Those jumpers that come with the panel whether just a screw or a strap are listed to do the job when installed according to instructions. Those instructions never mention removing paint though. Also the hole the screw threads into is usually a formed hole that has more meat for the screw threads to engage into and not just regular panel wall thickness with a drilled and tapped hole in it.

 

[hill900505]

Thanks guys for the replies. Is it correct to say that if a bonding screw/strap is provided or used as Main Bonding Jumper. The EGC to Neutral connection is made through the enclosure conductive path?

 

[kwired]

Thanks guys for the replies. Is it correct to say that if a bonding screw/strap is provided or used as Main Bonding Jumper. The EGC to Neutral connection is made through the enclosure conductive path?

Yes. Same goes for using metal raceways leaving that enclosure as the EGC for the circuits they contain. Locknuts on the raceway terminations bite through the paint to ensure bonding, so pre removal of paint is not necessary.

 

[infinity]

Thanks guys for the replies. Is it correct to say that if a bonding screw/strap is provided or used as Main Bonding Jumper. The EGC to Neutral connection is made through the enclosure conductive path?

And that path can only be for the EGC fault current to flow back to the neutral. You cannot connect a neutral to the EGC bus and use the enclosure as part of the neutral current path.

 

[hill900505]

Got it!!! Thank you so much.