Adding Ground Bus to 1960s Panel

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I assumed it was a service panel because of the one EGC on the neutral bar. But that may be a bad assumption... Don't see many EGCs, and don't see a green bonding screw, so not sure what it is. If this is fed from a feeder with the conduit as the EGC, that crow foot bonding wedge is a great solution for obtaining a wire type EGC to go to the ground bar.
 
In a legalistic sense, the ground bars for most panelboards are only recognized, so they can only be used in accordance with the manufacturers instructions for the panel board in the way UL says they can.
 
electrofelon said:
For a very very long time I hope. Even when using a matched ground bar and panel, I usually drill and tap new holes and move it because I don't like where they put the factory holes.
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This is problematic because two threads of engagement is required and a lot of panelboards are not 1/16" thick. The nubs you see for ground bars in panelboards are special punched so the material removed is used to thicken where the screw is located. If you drill your own holes they are not 1/16 inch thick unless the metal is that thick.
 
petersonra said:
This is problematic because two threads of engagement is required and a lot of panelboards are not 1/16" thick. The nubs you see for ground bars in panelboards are special punched so the material removed is used to thicken where the screw is located. If you drill your own holes they are not 1/16 inch thick unless the metal is that thick.
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Sue me! 😇
 
petersonra said:
This is problematic because two threads of engagement is required and a lot of panelboards are not 1/16" thick. The nubs you see for ground bars in panelboards are special punched so the material removed is used to thicken where the screw is located. If you drill your own holes they are not 1/16 inch thick unless the metal is that thick.
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What if your bar has two mounting screws? :unsure:

I've mounted these in many other enclosures besides cabinets for panelboards as well, I do remove paint before mounting or often use just galvanized non painted enclosures and then no paint removal needed.
 
petersonra said:
This is problematic because two threads of engagement is required and a lot of panelboards are not 1/16" thick. The nubs you see for ground bars in panelboards are special punched so the material removed is used to thicken where the screw is located. If you drill your own holes they are not 1/16 inch thick unless the metal is that thick.
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I had an argument with Don about this a while back in which I pointed out two things:
1) Actually most panelboard enclosures are 1/16" thick (although the OP is dealing with an old panel, so perhaps not in his case)
2) The way the code is written, if you have two screws you can take credit for one thread on each screw. 😉
 
kwired said:
Yes, I think some might be confused a little, I think this is the panel the feeder will originate in to the panel the OP wants to run an EGC to. If this is the service panel then he can land his EGC on the neutral bus of the panel in the picture.
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There's a service disconnect upstream. The panel in the photo isn't service equipment. I should have mentioned that in the original post.
 
Metal cabinets are required by 312.10(B) to be at least .053" thick before the application of a coating. That's less than 1/16" (.0625). My guess is that the old tub in the OP is at least 1/8" so it's more than thick enough to engage two threads.

312.10(A) Metal Cabinets and Cutout Boxes.
Metal enclosures within the scope of this article shall be protected both inside and outside against corrosion.
312.10(B) Strength.
The design and construction of enclosures within the scope of this article shall be such as to secure ample strength and rigidity. If constructed of sheet steel, the metal thickness shall not be less than 1.35 mm (0.053 in.) uncoated.
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infinity said:
Metal cabinets are required by 312.10(B) to be at least .053" thick before the application of a coating. That's less than 1/16" (.0625). My guess is that the old tub in the OP is at least 1/8" so it's more than thick enough to engage two threads.
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1960's cabinets and other metal enclosures almost definitely is thicker than same thing would be today.
 
petersonra said:
In a legalistic sense, the ground bars for most panelboards are only recognized, so they can only be used in accordance with the manufacturers instructions for the panel board in the way UL says they can.
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I now understand thats why they wanted me to use those grounding wedges, the old feeder had no wire type EGC. The wedge slips under the locknut of the feeder then provides a wire type jumper to the ground bar so fault current does not need to try to go across the screw - can - locknut etc.
 
gene6 said:
I now understand thats why they wanted me to use those grounding wedges, the old feeder had no wire type EGC. The wedge slips under the locknut of the feeder then provides a wire type jumper to the ground bar so fault current does not need to try to go across the screw - can - locknut etc.
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The feeder was run in EMT then the connector and locknuts on the connector were suitable as the EGC. A bonding wedge wasn't necessary but there is nothing wrong with exceeding the NEC minimum.
 
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