do I have to bond this?

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a7

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I have a 200A subpanel being fed from 800A panel.
Regarding 200A panel now. There are 4 small ground bars screwed right in on the panel metal box, each in one corner. The main grounding conductor coming from 800A panel is connected to only one ground bar, all 4 of them connect through the metal panel box though. Do I have to bond them using bonding jumper conductor or is the connection through the panel box enough??
Just thinking if one of them gets loose.
thanks in advance.
 
Re: do I have to bond this?

Originally posted by a7:
Do I have to bond them using bonding jumper conductor or is the connection through the panel box enough??
Click to expand...
You are not required by the NEC to connect these together with a bonding jumper.

If you want to install bonding jumper it is permitted.
 
Re: do I have to bond this?

I would suggest that if the UL listing says it is OK, than it is OK.

On the other hand, I would object if someone did something similar in a case where it did not have a UL listing.

The NEC lists those devices you can use as EGC (wire, EMT, IMC, etc). If it's not one of those things, then you can't use it.
 
Re: do I have to bond this?

Bob, (petersonra), I'm not sure I'm understanding. Do you mean you might object to the use of bonding terminals connected by bonding jumpers if the enclosure isn't listed for bonding terminals?

I don't think I get it.
 
Re: do I have to bond this?

Originally posted by physis:
Bob, (petersonra), I'm not sure I'm understanding. Do you mean you might object to the use of bonding terminals connected by bonding jumpers if the enclosure isn't listed for bonding terminals?

I don't think I get it.
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I would object to using something as an EGC that is not identified for that use.

For instance, I would not object (in general anyway) to using EMT as an EGC. I would object if someone brings an EGC into a steel column, tieing the EGC to the column, connecting another wire to the other end of the column and considering that a valid EGC. A steel column is not identified as suitable for use as an EGC, even though it is identified as suitable to use as a grounding electrode.

In the case you cited, if there were no factory holes for mounting the ground bars, I might well object to using the sheet metal of the box as an EGC. Wire is considered as a suitable EGC, so if someone were to mount ground bars in such an enclosure and tie them together with wire, I would consider that acceptable.

[ February 27, 2005, 07:32 PM: Message edited by: petersonra ]
 
Re: do I have to bond this?

Originally posted by a7:
Regarding 200A panel now. There are 4 small ground bars screwed right in on the panel metal box, each in one corner.
Click to expand...
If the panel was shipped and sold that way, I'd assume it was listed for the use that way. Panels often come with a #4 jumper between the neutral bars on either side of the bus to connect the two sides.

Without being able to see it, I'd assume that the grounding bars are installed using factory screws in factory holes. Who in the field would install four ground bars in each corner of the panel? :D

But I make many assumptions here. :D
 
Re: do I have to bond this?

GE panelboards usually come with 4 ground bars. You can mount one in each corner of the panel. Sure makes terminating ECG's easy.
 
Re: do I have to bond this?

Bob, (petersonra)

What bothers me is that I have seen far to many listed gadgets with threads that fail (in my opinion) far too easily. I guess I can't argue that it's best to be sure something is capable of performing.

I think I'm really kind of bothered that there's a perception that someone in general is incapable of bonding a piece of metal in the field while manufacturers in some cases have proven themselves to sometimes be no better or even worse, and have blanket acceptability.

I guess I think that if you're going to take out the microscope for someone in the field, you should do the same for the manufacturers. They ain't building stuff all that great either sometimes.

And this isn't rocket science, it's bonding.

Edit: And the bonding jumpers sort of make it A-OK.

[ February 28, 2005, 12:37 AM: Message edited by: physis ]
 
Re: do I have to bond this?

Well put.

I guess there are times we "improve" on things that kinda suck out of the box. Wish I could think of an example right this second... :D

Must be time for bed. :D
 
Re: do I have to bond this?

George? You should be counting sheep so that you have plenty of energy to argue with your boss tommorow. :D

Edit: I just can't get it right the first time.

[ February 28, 2005, 12:43 AM: Message edited by: physis ]
 
Re: do I have to bond this?

And you really think that just because you didn't do it he wont blame you. :)
 
Re: do I have to bond this?

Manufacturers of listed devices have been put under a microscope - the microscope has a name - UL.

If you look at the mounting holes provided for these things you will notice its not just a hole drilled in the sheetmetal. Its built up so there is adequate thread engagement for mounting the ground bar with machine screws.
 
Re: do I have to bond this?

That's true for this Square D panel I'm looking at but not for,

this:
5A052.JPG


Which is also UL listed. And both are 1/16" material.
 
Re: do I have to bond this?

It might be that for the intended use the ground connection does not require being beefed up for the 4x4 box, but does for the panelboard.
 
Re: do I have to bond this?

Originally posted by petersonra:
I would object to using something as an EGC that is not identified for that use.
Click to expand...
Panel enclosures are suitable EGCs. :cool:

We are allowed to use a metal raceway as the EGC for the feeder to a panel, we are not required to put a bonding bushing on the end of that raceway in order to provide a copper conductor from the raceway to any grounding terminal bars in the enclosure.

I would object if someone brings an EGC into a steel column, tieing the EGC to the column, connecting another wire to the other end of the column and considering that a valid EGC.
Click to expand...
True for EGCs, but perfectly acceptable for grounding electrode bonding jumpers. :cool:
 
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