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Quattro 03-12-2007 12:18 PM

A few electrical questions
My main service panel has one neutral/ground buss bar. It's full, and I need to clean it up because there are instances where grounds and neutrals are combined under one screw. This passed inspection when I bought the house, but I have been finding lots of things that our inspector missed...

Can I buy a separate ground bar, screw it to the main panel, and move all the ground wires to it? That will free up lots of space on the neutral panel so each circuit can have it's own screw.

Should that ground bar be attached to what will then be the "neutral only" bar with a heavy-gauge jumper?

Thank you!

Quattro 03-12-2007 12:44 PM

removed to clarify

JoeD 03-12-2007 05:43 PM

1. If by tandem breaker you mean one that takes up only one slot then no tandem breaker. A double pole 240 volt breaker would be fine. In some case they are required.

2. Yes can do that. One neutral per screw is a requirement for neutral wires.

3. The additional ground bus has nothing to do with the fact that the sub panel must be connected with a proper size ground wire. The ground bus itself needs no connections. It grounds to the frame of the main panel when it installs.

Quattro 03-12-2007 07:12 PM

Hey JoeD, thanks for the help.

1. I meant 2-pole breaker, with a connected handle (forgot the term for this).

2. That's what I thought...will do.

3. So the sub-panel does not need a ground feeder wire running to the main panel ground bus? The sub-panel grounding bus is (obviously) screwed to the sub-panel box itself.

Quattro 03-12-2007 08:36 PM

OK, a little more info:

- taking a voltage reading between the two circuits in question, I get 245V. According to another resource, this means the circuits are on opposite phases, and I shouldn't have a problem with the shared neutral. Is this correct?

Now, looking at the existing neutral/ground bus on the 20-space main panel:

- there are only 16 or 17 locators. How the heck is a guy supposed to have enough spaces on the bar to accomodate 20 circuits? Even if only 1/4 of the breakers have shared neutrals, that's still 15 inidividual spaces needed for neutral landings. That leaves 1 or 2 for ALL the ground wires? This just doesn't seem right.
Looking more closely at the ground/neutral bar reveals there are smaller holes right beneath the regular holes for securing the neutral wires. But, as far as I can tell, there is no way to secure a ground wire in these smaller holes. What are these for? I might have to snap a picture to reveal what I'm talking about here...if this is too confusing.

Thanks for the help.

Quattro 03-13-2007 09:35 AM


The overall main and sub panel:

A little closeup of the wire entries:

The FULL neutral/ground bus:

Another shot:

Quattro 03-13-2007 09:36 AM

The "mystery holes" on the neutral/ground bus under the regular screw-clamp holes:

glennjanie 03-13-2007 01:05 PM

The sub-panel is connected to the main with "compression fittings" which I personally don't trust for grounding. I wold keep the big green wire and move it to the higher (horizontal) bus bar along with the other ground wire that is connected to the vertical one.
I like the grounds being tied to the copper pipe but I would also want a driven ground rod outside.

JoeD 03-13-2007 04:42 PM

The sub panel needs a ground wire from the main panel. I thought you meant connecting a wire from the existing ground bus to the new one you want to install in your main panel.

JoeD 03-13-2007 04:47 PM

I also see a couple of breakers with two wires under the screw. Some breakers are rated two wires, some are not. I don't know which type yours are but that could be ans issue if they are not two rated.

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