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pacifier1er 05-29-2007 03:33 PM

advice on installing equipment grounding bar in main panel
2 Attachment(s)
I am hoping someone can help me. I am updating the wiring in my house. We have a Square D QON30MW150-1 series E8 panel board. Right now there is no room for any more neutral or ground connections. A few of the circuits in the house (probably the original ones) share a neutral. They run all around the house. I am trying to update the wiring in the bedrooms and plan to put in AFCI breakers which can't have a shared neutral. I also would need to ground all the circuits as many are not.

I wrote Schneider for some info on the best way to add a new grounding bar and received this cheerful information, "This load center (QON20MW150-1) that you have is over 25 Years old, and unfortunately we don't have an Installation Manual or any
Instruction sheets, still available, for this Old, Obsolete load center."

I have never seen a load center without the neutral/grounding bars on both sides. This one though only has it on one side. There are two hole left, but not alligned that seem to be where I could add another bar. Would this work? Would it be better (I think it would be better for space reasons and ease of wiring) to put the neutral bar on the other side? What would I need to do to bond the bar to the others if I placed it elsewhere and how would I mount it?

The grounding bar I bought (PK23GTA) says that if no mounting holes are provided to locate the bar on the back of the enclosure, by drilling two .147 (3.7mm) holes. Would I then connect the bar to the others with a 6 guage copper wire? Are there any issues/ things to look for in doing it this way?

I am attaching two pictures, one of the panel, and the second of the neutral lug/bar that shows the holes that are left.

Also every ground wire is in it's own terminal hole. I know on other panels I have seen and been told that you can put two or three grounding wires in one terminal, but never to mix ground and neutral, or put more than one neutral in a terminal. I don't think that would free up enough space, but would it be a good idea to gang together some of the ground wires?

Hopefully I have made sense. If I left out any details please tell me.

Thanks so much

JohnJ0906 05-29-2007 04:26 PM

I can't tell from the photo (might be the angle), but is there a screw, hopefully green, through the neutral/ground bar to the panel housing? There should be.
If so, you can screw the ground bar to the housing with no jumper, and put ground in the bar. You usually can put 2 grounds of the same size under the same screw, but check the chart that comes with the bar.
If you can find it, there should be a sticker somewhere with the permitted wire sizes in the panel. You might be able to double up grounds in the existing bar and free up enough spaces. Again, ONLY if the panel is rated for it, and only grounds of the same size.
Hope this helps.

JohnJ0906 05-29-2007 04:29 PM

Almost forgot -Don't move the neutral wires with the power on!

It would be best to do NOTHING AT ALL with power on.

Speedy Petey 05-29-2007 05:14 PM

Those later QO panels were rated for 2 or 3 grounds per hole. The old ones with the little clips under the screws were different.

SHUT OFF THE MAIN BREAKER and then you can move some grounds together. If you stay with two per hole you will be fine.
REMEMBER, the grounds MUST be of the same size to share a hole.

pacifier1er 05-29-2007 05:31 PM


Thanks so much.

Also thanks for the word of caution. I have been warned a few times that current flows through the neutral back to its source and can shock you just as bad.

I think the bar is bonded to the panel, but I couldn't see myself. If there is a screw it is hidden. Would it be reliable to check the voltage from the hot to the case to check if the panel is grounded. If it reads 120 Volts would it mean the case was grounded?

Also would the resistance of the case cause any issues with the new grounding bar? I have always seen something bonding the grounding bar to the neutral bar before, and figured this was to create a low resistance (path of least resistance) way to ground. Would feeding the neutral into the enclosure make the enclosure part of the circuit?

Thanks again for trying to clear this up for me, hopefully I am understanding everything.

johnny331 05-29-2007 05:55 PM


Originally Posted by pacifier1er (Post 46802)
Would it be reliable to check the voltage from the hot to the case to check if the panel is grounded. If it reads 120 Volts would it mean the case was grounded?

use the continuity function on your multimeter (with the power off) that will give you a resistance measurement of ohms. 0-ohms means no resistance, which is a good connection.

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