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my parents purchased a townhome with a qo panel that has neutral and ground bars bonded. Unfortunately for them, previous owners or service people did a rather shoddy job electrically speaking over the years. When repairing a leaky drain, I came across wires spliced in a wall without a junction box, which led me to opening other walls and ceilings to find junction boxes hidden in ceilings, inexplicable shared neutrals, and to top it all off, the panel is a mess, as you might imagine.

Because so many of the screws on the bonded neutral ground bus bars have 3 to 4 grounds and neutrals under them, I'm wondering if there's any problem with mounting a ground-only bar to the panel's raised points. I'm thinking no, but I just want to be sure that nothing is different since I would still have the neutrals running to the bonded bars

Thanks in advance, and if it's helpful, I can add a picture when I'm back at the house tonight.

Chris

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    If you want to attach to the raised points you will need to order the factory specific part. Other kits pay attention to the installation instructions. Often they come with self tapping screws that require a specific pilot size. – NoSparksPlease Jan 1 at 23:03
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    You're getting one of the official Square-D ground bar kits, right? (PKxGTA, where x is a number) – ThreePhaseEel Jan 2 at 1:29
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    Yes, each neutral bar must have only one wire under it. Grounds may be allowed 1 or 3, but the right answer is to have enough ground bars for everything. – Harper - Reinstate Monica Jan 2 at 8:58
  • Thanks everyone. I'm definitely using the factory part made for the pre-drilled holes in the panel. Appreciate the affirmation. – Chris S Jan 2 at 15:48
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First of all, let’s deal with your neutrals. It is against code and dangerous to have more than one neutral (“grounded conductor” in the language of the NEC) in a single hole/screw terminal of your ground/neutral bar. If it is the case that you have multiple neutrals in a single hole, that needs to be fixed.

408.41 Grounded Conductor Terminations. Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor. Exception: Grounded conductors of circuits with parallel conductors shall be permitted to terminate in a single terminal if the terminal is identified for connection of more than one conductor.

Why is this dangerous? This post goes into great detail. (Re-quoting the important part here because the source link within is dead and can’t link directly:)

The connection of a neutral and equipment-grounding conductor in the same termination creates a similar issue. One of the objectives of the particular arrangement of bonding jumpers, neutrals and equipment grounds is to allow circuit isolation while keeping the equipment grounding conductor still connected to the grounding electrode (see UL 869A - Reference Standard for Service Equipment). When the neutral is disconnected, the objective is to still have the equipment ground solidly connected to the grounding electrode. If both the neutral and grounded conductor is under the same terminal, this cannot be accomplished.

Now, as to your Ground wires, it is fine to add an additional ground bar to the panel, by using the SquareD part for the raised attachment points which should be pre-tapped to make an appropriate ground connection, or by installing a ground bar using appropriate drill size, tapping, and making sure two thread turns of the screws mounting the ground bar engage with the (unpainted) metal of the box.

Note that you should use this extra ground bar for ground wires (“grounding conductors” in NEC parlance) not for neutrals. You can have multiple grounding conductors in the same hole, provided the equipment manufacturer says the hole and lug are rated for more than one conductor. See details in this post including some other good code references for why multiple conductors are permitted under a lug when labeled so. Here is the pertinent NEC reference:

110.14 Electrical Connections ... Terminals for more than one conductor .... shall be so identified.

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    Thanks for your help. This confirms everything I suspected based on my research. It looks like I'll need to add ground bars to both lower sides of the panel, because of the lack of length in the present ground wires. It looks like a rat nest. Any advice on the order at which to clean it up? My thought was to leave all of the hot/neutral wires in place, and only moving the grounds that need to be moved that can reach the new Ground Bar. The tricky part is with the heavier gauge wires that need to be woven through other wires. – Chris S Jan 2 at 15:54
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    Yes, your approach sounds right. Since you can’t move the neutral wires to a different bar (although you should make sure they are single wire per hole, rearranging them on the existing bar), I would concentrate on getting the ground wires to a new bar or two, as you suggest. Be sure to de-energize the whole panel (flip the master breakers), and remember that the conductors feeding those master breakers will still be live. Although frowned upon by some, it is permitted to splice within the panel so you can do that in a pinch. – jbeldock Jan 2 at 19:00
  • Thanks again. Much appreciated. – Chris S Jan 5 at 14:39

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