Grounding Remote Distribution Panel

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  #1  
Old 04-10-07, 12:38 PM
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Grounding Remote Distribution Panel

Hi,

I've got a detached garage. I ran power (240V 1PH) to a distribution panel in the garage from the house's main panel. The power is run underground about 100'.

My question is regarding grounding the distribution panel. Should it have its own earth ground - or should I tie the ground buss bar to neutral?


Thanks!
 
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  #2  
Old 04-10-07, 12:44 PM
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Yes, a ground bar is required.

Did you run a three wire feed to the panel or a four wire feed? Are there any other connections to the garage, such as a metal water pipe, a telephone wire, a television wire, etc.?
 
  #3  
Old 04-10-07, 01:09 PM
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I ran 3 conductors w/ a bare ground (i.e., H-H-N-G).

The hot wires go to the breaker busses (obviously), netral to the neutral bar and ground to the ground bar.

So now I need to know what, if anything, to connect the ground bar to. Should it be tied to neutral -or- wired to an earth ground -or- left alone?

If left alone, it will be grounded though the bare conductor back to the house's main box. I'm just not sure if it needs a local ground.

There is no other utility service in the garage - no pipes, phone, nothing. I can easily sink an earth ground if need be.
 
  #4  
Old 04-10-07, 01:15 PM
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Yes, a ground bar is required (as stated earlier).

That statement was absolute with regard to a detached garage and a sub panel.

The ground bar connects to the ground buss. The ground buss and the neutral buss must remain isolated.
 
  #5  
Old 04-10-07, 01:22 PM
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Okay, thanks. I was confused by your earlier answer. I thought you were saying a ground buss bar was required & I obviously have one.

So what you are saying is that I need to sink a ground rod and wire it to my ground buss bar. Gotcha.

Thanks!
 
  #6  
Old 04-10-07, 03:47 PM
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You may end up need two ground rods to sink it in the ground [ most area will ask for two rods unless specal approval from inspector can get away with one rod { that i doubt } ]

and make sure you have min of # 6 bare copper wire run from subfeed box to ground rod[s].

if more question just post it here


Merci , Marc
 
  #7  
Old 04-10-07, 04:07 PM
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I may be wrong, but I think racraft mistyped.

The original question is not valid, as it is an either/or question. "My question is regarding grounding the distribution panel. Should it have its own earth ground - or should I tie the ground buss bar to neutral?"

No matter what, a detached building needs to have it's own ground rod.

The question is if you need a three wire feed, and then you would tie the ground and neutral together as if this were a main panel. Or, if you should have a three wire plus ground feed, and seperate the ground and neutral.

If there are any other metal paths between the two buildings, you must run a three wire feed plus ground wire. This includes: phone, water, gas, kite string, even metal water that goes back to the street utility and is metal to both buidings. Do this even if you are not sure, but might want to add a phone in the future, or added an empty conduit for future use.

If there are no other metal paths between the two buildings, you may run a three wire feed without a ground.
 
  #8  
Old 04-10-07, 04:39 PM
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Make sure you understand the difference between a Grounding Electrode Conductor (GEC), which is the wire that runs to a grounding rod, and an Equipment Grounding Conductor (EGC), which is the bare wire that runs between buildings. They are two different things and serve two different purposes.

You need the GEC in any case, and since you already ran the EGC, you should use it. Keep the neutrals and grounding wires electrically isolated in the subpanel, which means that your neutral bar must be isolated from the shell of the panel. That means that if a green screw was supplied with the panel, you should throw it away.
 
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