detached garage grounding

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Lefty0824

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New Jersey
100 amp main lug sub-panel in a detached garage am I required to drive a ground rod? I pulled an equipment grounding conductor with the phase conductors in the conduit.
 

augie47

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Tennessee
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Per 250.32 you are required to have a grounding electrode system.
If no other electrodes are present you would need a ground rod, and based on 250.56, perhaps a 2nd.
 

Dennis Alwon

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Chapel Hill, NC
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As Gus said, then separate the neutral and grounds and install the GEC to the ground bar. You also need a main or use the 6 disco rule.

If you only have a MWBC then no rod is necessary.
 

infinity

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New Jersey
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You said main lug (MLO), where's the building disconnecting means or do you have 6 or less CB's?
 

infinity

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there is a 2 pole breaker feeding the MLO panel with 6 breakers and wired as sub-panel isolating the neutrals.

So the garage has no single disconnect located at the structure just the 6 CB's in the panel at the garage?
 

curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
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Every panel I have seen states that they are suitable for use as service entrance equipment if a main breaker is installed. If that is the case simply having 6 or less branch circuit breakers without a main would not be compliant.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
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Electrical Contractor
In a nutshell, the separate building is wired as if it was a service, plus like a sub-panel with a 4-wire feeder.

Every panel I have seen states that they are suitable for use as service entrance equipment if a main breaker is installed. If that is the case simply having 6 or less branch circuit breakers without a main would not be compliant.
I disagree. I take it as meaning it;s definitely suitable with the main, and may be without it, if you meet the rules.
 
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taylorp

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What about 250.56???

A supplemental ground rod is only necessary if the single electrode does not have a resistance to ground of 25 ohms or less. 250.56 was deleted in the 2011 code, you should now reference 250.53(A)(2) in the 2011 code.
 

infinity

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A supplemental ground rod is only necessary if the single electrode does not have a resistance to ground of 25 ohms or less. 250.56 was deleted in the 2011 code, you should now reference 250.53(A)(2) in the 2011 code.

And it's replacement section clearly states two rods unless you can meet the new exception.
 

iwire

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Massachusetts
Every panel I have seen states that they are suitable for use as service entrance equipment if a main breaker is installed. If that is the case simply having 6 or less branch circuit breakers without a main would not be compliant.

In my experience, many but not all.


I disagree. I take it as meaning it;s definitely suitable with the main, and may be without it, if you meet the rules.

I agree with curts take on this.

If it is suitable for service equipment with no main it will clearly say so. Somewhere I have a picture of the wording but it goes something like this.

'Suitable for service equipment with main breaker kit or no more than six branch breakers installed'
 

Dennis Alwon

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Chapel Hill, NC
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I am really curious as to what the difference would be. There are some panels I have seen that will not accept a main breaker kit so I assume - never checked, that it is not suitable for service equipment.

I guess if it is suitable for service with a main what possible can be different with six breaker rule? :confused:
 

dana1028

Senior Member
I am really curious as to what the difference would be. There are some panels I have seen that will not accept a main breaker kit so I assume - never checked, that it is not suitable for service equipment.

I guess if it is suitable for service with a main what possible can be different with six breaker rule? :confused:

I don't know either - but I have such a panel at my house - in addition to the 6-breaker rule is the restriction that there can be no 110V [line-neutral] loads on any of the 6 breakers [sorry, installed 'bout 8 yrs. ago and the writing in the panel is faded enough I can't photo it].

It's a QO8-16L100D [didn't find any details about it at Schneider].
 
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