Breaker panel 'bonding"?

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  #1  
Old 09-22-09, 06:44 AM
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Breaker panel 'bonding"?

I have some basic electrical knowledge having renovated multiple homes and doing some of the basics myself while leaving the major work to professionals - like increasing from 200a to 400a with new panels, etc. In this instance I think I can handle this but want to make sure what is needed.

A home inspector noted in his report that "The breaker panels were not bonded to the grounding buses. Should a short circuit occur, the breaker panels would become energized rather than sending the short circuit to ground."

What is needed here? Is this a heavy copper wire from ground bus to a screw on the back of the metal box? Please reply with all necessary details if you have pointers here.

This is a 200A main service with a 100A sub panel directly next to it. Westinghouse / Bryant panels. thanks!
 
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  #2  
Old 09-22-09, 06:56 AM
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In the main panel only the neutral is grounded to the metal enclosure either with a grounding screw through the neutral bar to the panel or a strap to the panel. Which depends on make and model of panel. The ground bar if any is mounted directly to the metal box and therefore bonded. This is the only time the neutral is bonded. In subpanels the neutral is always insulated from the box and only the ground bar is bonded to the box.

Main panel is the first panel with an over current protection device (OCPD). All other panels are sub panels. Sometimes the first OCPD is built into the meter base and what appears to be a main panel is really a sub and therefore wired by the rules for a sub panels.

As to what the inspector meant that is hard to say. Any ground bar is bonded/grounded. Does your subpanel have a ground bar? If not it needs one and neutral and ground wires in the appropriate place.
 

Last edited by ray2047; 09-22-09 at 07:24 AM.
  #3  
Old 09-22-09, 07:37 AM
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It seems unlikely that the main panel case wouldn't be grounded. Could you post a picture of the inside of the panel(s) to a photo sharing site and give us the link? I'm just not sure what the inspector could be seeing that would make it look like the panel wasn't grounded. Flickr, photobucket, imageshack, etc would all be acceptable.
 
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Old 09-22-09, 07:45 AM
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Flickr, photobucket, imageshack, etc would all be acceptable.
But not TinyPic.


...................
 
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Old 09-22-09, 07:54 AM
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pics

Thanks guys! Here are some pictures. It appears that the problem is coming to light now. Take alook and let me know how to remedy if you can:

This is a picture of the sub panel neutral and it appears that they just grounded this like a main panel whereas it should be separated.



Here is another picture of the sub panel and what I believe to be the separate ground bus. two questions - if I need to move the grounds from the other side to here - what happens if the wires are too short? Also - what do you think this VERY large wire is that is attached here and then goes out the top. It could possibly be going to the AC units or maybe something else. I think the only things in this box are two ACs, the stove, the dryer and a jacuzzi.



Here is apicture of the main panel. I put in this "bonding screw" after the fact as someone advised that this may be the issue. Now that seems very unlikely. Should I leave it or remove?

 
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Old 09-22-09, 10:02 AM
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Yes, all ground wires must be moved to the ground bar on the left in the subpanel. Be sure the neutral bar in the subpanel is isolated from the panel.

The black ground cable should be re-identified with green tape and neutral feeder with white tape (or marker) to be code compliant.
 
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Old 09-22-09, 10:09 AM
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Thanks again - just to verify:

"Yes, all ground wires must be moved to the ground bar on the left in the subpanel. Be sure the neutral bar in the subpanel is isolated from the panel."

If the ground wires are not quite long enough to make it can use wire nuts and extend the grounds to the appropriate bar? If so what guage should I pick up if I need some more bare ground wire?


"The black ground cable should be re-identified with green tape and neutral feeder with white tape (or marker) to be code compliant."

Both of these in the sub panel?

Also - what about the 'grounding screw' I installed in the main? Should I remove it? It was noted in one of the pictures with just the bare copper going to the lone terminal.

THANKS AGAIN!
 
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Old 09-22-09, 10:43 AM
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Originally Posted by scb71 View Post
If the ground wires are not quite long enough to make it can use wire nuts and extend the grounds to the appropriate bar? If so what guage should I pick up if I need some more bare ground wire?
Yes you can extend it. With grounds you can group them and extend to the bar with the same or bigger AWG wire as the largest wire in the group. If the neutrals need to be extended, you cannot group them and the extension must be the same AWG or larger as the original white wire.

Both of these in the sub panel?
Yes and also where those wires terminate in the main panel. The wires need to be color coded on each end.

Also - what about the 'grounding screw' I installed in the main? Should I remove it? It was noted in one of the pictures with just the bare copper going to the lone terminal.
It is okay to remain. Not sure if it's required because I can't quite tell if the neutral bar is bonded to the case. In either case it doesn't hurt anything to be there.
 
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Old 09-22-09, 11:49 AM
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Here goes - take a look and let me know if all looks well. I rerouted the grounds to the separate ground bar and had to lengthen two of them to avoid stretching too much.

 
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Old 09-22-09, 03:40 PM
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Looks good. Now you just need to remark the cables green and white. White out and green magic marker would do or you can buy a package of marker tapes. Cut the main breaker and be careful. Even with the main breaker off there are hot parts around it.

Just a comment whoever installed that sub panel gets the dummy award. Normally the ground bar is purchased separately so he had to buy a ground bar, install it, run a cable to it, yet he didn't use it.
 
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Old 09-23-09, 06:37 AM
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Thanks again for all of your help. I have to agree on the dummy award part...

Now to clarify on the white and green marks. Is that necessary because so many wires are black and look the same? Also - am I marking that large green wire with the green strip and then just marking the large black that goes to the neutral bus with white? Is the same needed in the other panel as well?
 
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Old 09-23-09, 07:24 AM
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Originally Posted by scb71 View Post
Thanks again for all of your help. I have to agree on the dummy award part...

Now to clarify on the white and green marks. Is that necessary because so many wires are black and look the same? Also - am I marking that large green wire with the green strip and then just marking the large black that goes to the neutral bus with white? Is the same needed in the other panel as well?
Code states the ground must be either bare or have green insulation. No other color is acceptable. However if the wire is larger then #6 the code permits another color so long as it is reidentified with the correct color. Neutral is the same. Must be white but can be reidentified if larger then #6. Must be done on both ends.

Our dummy at work again. Four black wires, how does he know which is which. Any way easy to see why the code requires this.
 
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