Ground Buss

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  #1  
Old 06-02-06, 02:27 PM
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Ground Buss

Scenario:
Running wire from the house to a separate garage.
Main panel to a sub in the basement, from there to the garage sub. (I know there are guys against this--has to be done this way. Hardly anything on the basement sub so far).
Main panel 60 amp breaker, 6 gauge to sub. Sub panel 40 amp breaker, 8 gauge 8-3 type UF-B buried in 1 1/4 inch schedule 40 24 inches deep, 70 foot underground run.
Questions:
I know that I need another ground buss as the sub panel distribution box has only 1 neutral buss. Do I need stand-offs between the ground buss and the box? It would seem that I would as the ground buss would be at the same potential as the box would be. I've seen a variety of busses that you can buy, but none come with a plastic separation between them and the box.
I'm going to drive a copper grounding rod next to the garage and connect to the ground buss. I also connect the ground from the first sub to this?
How can I make this a neat installation when running the ground wire into the wall. Could I run a separate section of conduit with the ground wire in it?
What size wire should I use for the ground buss to rod?
Some guys would think that 40 amps isn't much and it isn't. But it will keep the kegerator, fan and radio going!
 
  #2  
Old 06-02-06, 02:56 PM
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The ground bus you add to the sub panel should not have standoffs. It MUST connect to the panel. The neutral buss should have standoffs.

You need a ground rod at the garage, but it is the only connected to the garage panel. The main panel should already have it's own ground rod or other means of a ground. 8 gage protected by conduit is allowed.
 
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Old 06-02-06, 03:01 PM
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Originally Posted by Don W
Scenario:
Running wire from the house to a separate garage...70 foot underground run.
Sounds like you have everything covered there. Remember to keep the grounds and neutrals isolated in both subpanels.

Do I need stand-offs between the ground buss and the box? It would seem that I would as the ground buss would be at the same potential as the box would be. I've seen a variety of busses that you can buy, but none come with a plastic separation between them and the box.
You want no stand-offs between the subpanel and the ground bus. In fact, you want to make sure there is a good connection between the two.

The neutral bus, on the other hand, should be insulated from the subpanel box. You want to ensure there is no connection there.

I'm going to drive a copper grounding rod next to the garage and connect to the ground buss. I also connect the ground from the first sub to this?
The bare wire in the UF-B feeder and the GEC to the ground rod both connect to the ground bus in the subpanel.

How can I make this a neat installation when running the ground wire into the wall. Could I run a separate section of conduit with the ground wire in it?
Yes, a piece of 1/2" conduit with an LB fitting or access elbow will be sufficient. You could also zip-tie it to the back of the vertical conduit that brings your feeder in. You should make sure it is reasonably protected from damage.

What size wire should I use for the ground buss to rod?
This is called the Grounding Electrode Conductor; minimum GEC is #8 copper or #6 aluminum in this case.
 
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Old 06-02-06, 03:30 PM
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Thanks very much for the reponses. You guys rock as well as this forum!
 
 

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