Grounding/Bonding - Detached Garage - Inspector vs Electrici

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kenb123

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Please help a homeowner.

Main House - 400 AMP Service Panel. Murray. Villa Park, California. Orange County.

Detached Garage - approx 50 feet from panel. Inside a 3/4 PVC pipe 2 #6 THHN Black Wires, 1 #6 THHN White Wire, and 1 #10 THHN Green wire were run. Connected at Main Panel to double 60 AMP breaker, Neutral, and Ground.

In the Detached Garage a Murray Sub Panel.

Disagreement between the Electrician and the Inspector.

Electrician says install a grounding bus in the box and connect the #10 green to it, connect the White to the neutral Bus. Do not bond them, keep them isolated, and DO NOT install a grounding rod. Logic is if house loses white and ground, then #10 Green becomes a heating coil.

Inspector says - all I know is code - Install a Grounding rod, connect it to the Neutral Bus along with the green wire. No separate ground bus, all green/white go on the same bus.

Help please?
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
The inspector should read the code before he claims to know it.

The inspector is mistaken and should look at 250.24(A)(5).

Than he could also look at 250.32(B)(1) and 250.32(B)(2).

There are basically two ways to handle this panel in a separate structure.

Where you have both a 'white' and 'Green' at this remote panel it is a code violation to connect them together.

Your EC has done the right thing.
 
charlie b

charlie b

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Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
They're both wrong.

You need a ground rod. Reference NEC Article 250.32(A). The Inspector is right about this, and the electrician is wrong.

You need to separate the neutral (white) from the equipment grounding (green). Reference NEC Article 250.32(B)(1). The electrician is right about this, and the Inspector is wrong.

Please note that there is an alternative to having the neutral and ground separated in the sub-panel. But that alternative is not available in the situation you describe. The alternative appears in NEC Article 250.32(B)(2). It starts by saying that if you don't run the green wire, you can . . . . But you did run a green wire, so you might as well stop reading at that point.
 
E

eprice

Senior Member
Location
Utah
They are both wrong.

The electrician is right when he says that a grounding bus is needed, and that the green equipment ground and the white (grounded conductor) should be kept isolated at the garage panel, but he is wrong when he says there should be no ground rod.

The inspector is correct when he says install a ground rod, but he is wrong in requiring interconnection of the white (grounded conductor) and the green equipment ground.

Have them sit down and read 250.32(A) and 250.32(B)(1) together.
 
K

kenb123

Member
Thanks - Now What

Thanks - Now What

Thanks for the prompt and helpful responses. You both agree that the Green and White remain Isolated in the subpanel (which makes sense to me). But you seem to disagree on the grounding rod.

So I can argue with the Inspector and cite 250.24 (A)(5), 250.32.(B)(1) and 250.32(B)(2) for the Isolated/Non Isolated Issue.

As long as he goes along with the Non Isolated Approach then is it a No Harm/No Foul if I just have the Electrician sink a Ground Rod and keep it connected to the isolated ground bus?
 
charlie b

charlie b

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Location
Lockport, IL
Occupation
Retired Electrical Engineer
Re: Thanks - Now What

Re: Thanks - Now What

kenb123 said:
So I can argue with the Inspector and cite 250.24 (A)(5), 250.32.(B)(1) and 250.32(B)(2) for the Isolated/Non Isolated Issue.
Click to expand...
With respect, I suggest that you not be the one to "argue" with the Inspector. All he or she would have to do is to starting talking about the rules for grounding and bonding, and you would be lost. Also, you would not be aware if you were inadvertently using words in an incorrect or inappropriate manner. For example, you used the phrase "isolated ground bus." That phrase has a real meaning, but its meaning has nothing to do with your situation.

Arguing with the Inspector should be the job of your electrician.
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Sorry guys I missed that the EC was saying no to a ground rod. :oops:

I agree both the EC and the inspector are wrong and I agree with the other posters that you need electrodes of some type at the separate building and it should not be you dealing with the inspector.
 
eric stromberg

eric stromberg

Senior Member
Location
Texas
To re-iterate what other posters have said.

1 - Neutral bus in garage panel needs to be insulated from the case (remove the bonding means)

2 - The sub-panel needs to have a ground bar in it, electrically connected to the case.

3 - The ground rod at the panel (required) needs to be connected to the ground bar in the sub-panel. It cannot be connected to the neutral bar.

Eric Stromberg, P.E.
 
K

kenb123

Member
Thanks again

Thanks again

Sorry, I should have clarified, I won't be arguing with the Inspector, the EC can do that .

The POINT that can be argued is that per 250.32(A), 250.32(B)(1), 250.32(B)(2), and 250.24(A)(5) the green wire goes to an Isolated Ground Bar, the White goes to it's own isolated Bar, and a Ground Rod will be installed and run to the ground bar. NO Bonding will be done between the Green and White within the sub panel.
 
K

kenb123

Member
Yes - Last Post

Yes - Last Post

Like it says above - That's why it won't be me arguing with the Inspector.

As you said:

The white is connected to the Neutral Bar/Buss and "Isolated" from the Green (No Bonding) and "Insulated" from the case.

The green is connected to the Grounding Buss/Bar and "Isolated" from the White, but connected to the case

The Ground Rod is connected to the Grounding Buss/Bar and Not connected/bonded to the Neutral.
 
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