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Old 04-16-2011, 06:48 PM   #1
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Multiple Grounds under one screw in panel


Hi,

I have been reading some discussions where people are saying that it is ok to put two grounds under one screw, depending on the panel instructions.

I am running into some problems that others are having where there is still room for more breakers (4 to be specific) but only have one or two spots left on the neutral/ground bars.

I have a Murray LC120DC panel and it says the following: "Equipment ground bar terminals are suitable for the following combinations: Small Terminals: One 14 to 6 AWG CU; one 12 to 6 AWG AL; Two 14 AWG CU; Two 12 AWG CU; Two 12 AWG AL Solid Wires."

I left off the requirements for the large terminals because they don't apply to my question.

So, do the statements in bold say that it is ok to have to two grounds (12 or 14 guage wire) under one terminal? Is it only ok to do on one of the bars or is it fine for both?

Also, does anyone know why some panels allow for two grounds under one terminal and others do not?

Thanks.
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Old 04-16-2011, 07:31 PM   #2
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Multiple Grounds under one screw in panel


Grounding conductors can be doubled in your panel. These will be bare or green insulation. Grounded conductors need to terminate in a hole unshared with anything.

The difference is in the listing requirements and the electric code.

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Old 04-16-2011, 07:37 PM   #3
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Multiple Grounds under one screw in panel


Quote:
Two 14 AWG CU; Two 12 AWG CU; Two 12 AWG AL Solid Wires."
Quote:
So, do the statements in bold say that it is ok to have to two grounds (12 or 14 guage wire) under one terminal?
it means exactly what it states.

you can put 2 copper # 14 wires under one terminal
you can put 2 copper #12 wires under one terminal
you can put 2 #12 aluminum solid wires under one terminal

No other combinations of multiple wires is acceptable. In other words, you cannot mix #12 and #14 under 1 terminal.
This applies only to ground wires and not neutral wires.
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Old 04-16-2011, 08:29 PM   #4
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Multiple Grounds under one screw in panel


Alternatively you can take a few ground wires (not neutral wires) off the bus bar, wire nut them to a short length of bare wire (size equal to the larger(est) of the group), and re-attach the short length leaving a few holes free for other wires.

Neutral wires must be connected to the bar to which the fat neutral of the service cable is attached, or to another bar with a metal strip between it and the former bar. Ground wires may be connected to any bar that has metal to metal contact with the back of the panel.

Grounded conductor -- Formal name of what we often call the neutral. Actual grounding properly occurs only at once place, where the first disconnect switch (e.g. the main breaker) for the power supply is.

Grounding conductor -- What we refer to as a ground wire.
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Last edited by AllanJ; 04-16-2011 at 08:41 PM.
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Old 04-16-2011, 08:31 PM   #5
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Multiple Grounds under one screw in panel


Quote:
Originally Posted by AllanJ View Post
Alternatively you can take a few ground wires (not neutral wires) off the bus bar, wire nut them to a short length of bare wire (size equal to the larger(est) of the group), and re-attach the short length leaving a few holes free for other wires.
you can. I wouldn't. It looks tacky, IMO. I would install another ground bar.
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