Thread: Ground/Nuetrals in Garage Panel/Rewire

On a 25 year old house that's being completely rewired, including replacing service and other panels, shouldn't the ground and nuetrals be separated at the garage panel box which is 60 feet away from the service and grounding rod?

The electrician connected them together and didn't run a ground wire between the service and garage panel boxes and let water leak into the garage panel box from the weatherhead he removed weeks earlier. He was fired.

The new electrician says having the ground/nuetrals connected together is ok....I still recommended he separate them. He doesn't want to go to the trouble of running a ground wire the 60 feet from the service to the garage panel as he's indicated that its just not necessary.

So, my question is: Would drilling a hole in the garage foundation, under the garage panel box, and driving and connecting a grounding rod at this location do the job. So the house would have two (2) ground rods...one at the service and one at the garage panel. Would this be adequate or even superior to running a ground wire to the service over 60 feet away?

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Is the garage a free standing structure or is it connected to the house?

Originally Posted by Al Roden

So, my question is: Would drilling a hole in the garage foundation, under the garage panel box, and driving and connecting a grounding rod at this location do the job.

No. That would be creating an even different problem.

So the house would have two (2) ground rods...one at the service and one at the garage panel.

That would only be okay if a properly sized grounding electrode conductor was run between the two ground rods, and then, why bother to drive the other ground rod 60 feet away? All that is going to do is create a potential voltage potential between the two ground rods, and the bond run between them is trying to cancel it out and short the two rods together - at 60 feet, you could have a voltage drop on that bond should there be current on the grounding electrode system.

Would this be adequate or even superior to running a ground wire to the service over 60 feet away?

Absolutely not, it would be INferior to *just* running the proper size ground wire between the two panels, and, beside, that same basic size wire would need to be run between the ground rods - so nothing is gained, and there is cause for loss.

Thanks...that answered my question...NOW, i'll walk out to the garage and tell the electricians. I'll let you know what they say.

Hey Al, 'haven't heard from you for a long time.
The sparkys probably went to lunch.
Is this your house?

Hi Richard...yep..it's my house. It's really testing my inspection abilities too. We tore everything out to the studs and bear concrete floors and started over - even raised the ceilings in most of the rooms which had me scratching my head allot as to whether its going to hold up or not.

The electricians (there are two of them out there) finally agreed that it would be a better ground to just run a fourth wire from the garage panel box to the service entrance box and go ahead and isolate the grounds.

They're having fun out there trying to figure out where all the wires run to - there are a BUNCH of three and four way light switches...or there will be when they figure out which wires go where. The last electrician didn't label lots of stuff and used lots of junction boxes.

Sounds like these electricians figured out who is paying them.
Been there, done that.
Our house was originally built in '52. It was 1800'. Since then, the attached garage was converted - now office and junk, er tool room!
Rear sun porch enlarged, ceilings raised, etc.
Room addition for an art studio - wife teaches.
Now up to 3500'
About to add over sized detached garage - 22 x 35 and planning for the possible conversion of that to a studio.
We thought about moving - but, we're in too deep , so we'll just keep going. Eventually, will convert something for a downstairs master bedroom - stairs are getting to be a bitch.

Originally Posted by Jerry Peck

Absolutely not, it would be INferior to *just* running the proper size ground wire between the two panels, and, beside, that same basic size wire would need to be run between the ground rods - so nothing is gained, and there is cause for loss.

The neutral and grounds would still have to be separated and isolated, but doesn't the NEC allow the other panel to have it's own grounding rod provided that the required separation distances are maintained?

I thought that there were 3 methods of wiring this.

1. 3 wire system with metalic conduit.
2. 4 wire system where the 4th wire is the ground.
3. 3 wire system with a separate grounding source, providing that the buildings are totally separated (electrically speaking) and there are no grounding/bonding paths back to the original service equipment.

What about 250.32?

This is specifically why I quoted Al in my post:

Originally Posted by Al Roden

So the house ...

"THE house" (singular)

... would have two (2) ground rods ...

THE HOUSE "would have two" ground rods. (singular "house", plural "ground rods")

one at the service and one at the garage panel.

Giving the location of those TWO ground rods at THE house.

Thanks Jerry, you the man.

Article 250 of the NEC has got to be the worst example of editing and grammar in print today. What makes matters worse is that the very concept of 'ground' is rather muddled.

A "Code answer" is pretty hard to give, considering the substantial changes to the code over the years. Yet, I will try to sum things up.

It's pretty clear that a building has but one service - one place where the PoCo brings in its' lines, and sets it's meter. What happens next is where things get convoluted.

For example, that service drop may be immediately divided up, and sent to several separate meters / disconnects. In this example, every one of those separate panels is treated as a "main" panel.
A comparable situation can arise where several buildings are served by the same 'drop.' Until the 08 NEC, it was allowed to treat each building as if it had a separate service. The latest code makes it clear that this is no longer the case .... one meter, one 'main' .... and everything else is a 'sub.'

The effect is that the ground is bonded to the neutral at but one point - and that point is near the meter, at the first disconnecting means.
Why? Because electricity is always trying to go 'home.' "Home," in this case, is the PoCo transformer - NOT mother earth! A sure fault path back to the transformer is what makes breakers work.

Don't confuse this with the ground rod / grounding electrode system. They exist for an entirely different reason. That reason is, simply, lightning. Indeed, much of the modern world get by just fine without such a system.
Since it simply wouldn't do for, say, the living room to be at a different potential than the dining room, we require all these electrodes to be tied to each other ... dirt is a poor conductor. In location where the risk is greatest, additional means are required to ensure that everything is at the same potential.

John,

Usually ... your posts are so far fetched and out of whack that I have to tear them apart section by section to correct them, but ...

however ... except for a few corrections on terminology - that last post of yours above was pretty good.

I figured I owed you this post as usually I am having to do just the opposite.

"The effect is that the ground is bonded to the neutral at but one point - and that point is near the meter, at the first disconnecting means.
Why? Because electricity is always trying to go 'home.' "Home," in this case, is the PoCo transformer - NOT mother earth! A sure fault path back to the transformer is what makes breakers work."

Which is one of the reasons that all electrical installations are grounded, including the utility company transformers and switching stations.

"Don't confuse this with the ground rod / grounding electrode system. They exist for an entirely different reason. That reason is, simply, lightning. Indeed, much of the modern world get by just fine without such a system.
Since it simply wouldn't do for, say, the living room to be at a different potential than the dining room, we require all these electrodes to be tied to each other ... dirt is a poor conductor. In location where the risk is greatest, additional means are required to ensure that everything is at the same potential."

The grounding electrode is there for more than lightning. It is there to make absolutely sure that stray current does not kill. Stray current is a real issue, and you might be surprised at how often it is present in urban residential installations.