Ground bar mounting- where to find approved methods

[gbd5]

I'm looking for a path that may allow addition of a ground bar to a service panel for which the new bar was not specifically listed, and mounting will not utilize screws into pre-tapped holes.
Where may I find a path (listing & code wise) that allows an alternative means of installation?

 

[raider1]

Welcome to the forum.

As far as the NEC is concerned, 250.8 deals with the connection of grounding and bonding equipment.

Chris

 

[LarryFine]

Welcome to the forum.

Ditto!


Typically, you'd just drill and tap a two or three holes on the panel's rear surface, say 8-32, and mount the strip with two or three matching screws.

I always remove and save unused grounding strips from panels when I install them. You never know when you'll need to add an extra bus strip.

 

[infinity]

Ditto!


Typically, you'd just drill and tap a two or three holes on the panel's rear surface, say 8-32, and mount the strip with two or three matching screws.

I always remove and save unused grounding strips from panels when I install them. You never know when you'll need to add an extra bus strip.

I agree with Larry just drill and tap your own holes. You can use the screws that came with the ground bar.

 

[celtic]

Ditto!


Typically, you'd just drill and tap a two or three holes on the panel's rear surface, say 8-32, and mount the strip with two or three matching screws.

I'd prefer at least a #10 screw....that seems to the standard on tails and boxes.

 

[Sharpie]

Do any of you run a jumper from the existing ground bar to new one (in addition to the drill and tap)?

I do.

 

[mcclary's electrical]

10/24 for ground......

 

[Pierre C Belarge]

Ditto!


Typically, you'd just drill and tap a two or three holes on the panel's rear surface, say 8-32, and mount the strip with two or three matching screws.

I always remove and save unused grounding strips from panels when I install them. You never know when you'll need to add an extra bus strip.

I disagree with this procedure.
1. Manufacturers list products and have instructions for locations for the installations of terminal strips in their enclosures.

2. drilling and tapping holes in the enclosure may not provide one with the 2-threads minimum necessary for termination.


Fault current is going to be flowing across the screw termination into the the metallic enclosure, it is essential that the termination does not increase the impedance of the fault current path. If one is going to install a terminal bar to the enclosure, I suggest the use of a bolt and nut, with the appropriate washers.

 

[LarryFine]

Do any of you run a jumper from the existing ground bar to new one (in addition to the drill and tap)?

I do.

A conductor jumper would be necessary for a neutral bus, but a grounding bus may be bonded through the enclosure metal.

 

[LarryFine]

Fault current is going to be flowing across the screw termination into the the metallic enclosure, it is essential that the termination does not increase the impedance of the fault current path. If one is going to install a terminal bar to the enclosure, I suggest the use of a bolt and nut, with the appropriate washers.

You believe a nut and bolt provides better conductivity than a threaded hole? I would think most enclosures are thick enough for a 32-pitch bold to engage two threads.

The nut and bolt might not even break through a paint layer, unless you're using aggressively-toothed lockwashers (which may be what you mean by 'appropriate' washers).

 

[jimport]

IIRC the instructions from CH call for a hole to be drilled and then tapped.

 

[Sharpie]

If you drill and tap, do you still scrape/dremmel the paint?

 

[LarryFine]

If you drill and tap, do you still scrape/dremmel the paint?

I will for a single lug, but a strip with multiple screws will normally only have to carry a single circuit's fault current, and for a very short (pardon the pun) time.

 

[petersonra]

The shell of panelboard is not one of the EGCs listed in 250.118, so IMHO, you need to run a wire between the two ground bars.

 

[don_resqcapt19]

10/24 for ground......

The standard grounding screw is a 10-32.

 

[raider1]

The shell of panelboard is not one of the EGCs listed in 250.118, so IMHO, you need to run a wire between the two ground bars.

So by this logic we need to run a bonding jumper between conduit entrys in a 4 square metal box, because a 4 square metal box is not listed in 250.118?

Chris

 

[mcclary's electrical]

The standard grounding screw is a 10-32.

You're right, I don't know what
I was thinking. But I went to the tuck and found several ground bars, but only two of them were new
1) QO says in the instructions If no mounting holes are provided, use a #26 bit to drill (2) .147 diam. holes in the back of enclosure using the grounding bar as a template.

2) The second one is a GE and it does not offer an alternative method, it says
Use the enclosed 10/32 screw to mount into the factory predrilled holes in the enclosure

They're the only ones I have within my reach