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I am installing a new 4 position outdoor electric panel. The panel has a neutral bar that is mounted on the right side of the breakers on a plastic plate that is one piece holding the CB's as well (I can remove the bar but not the plastic isolation piece).

I want to install a grounding bar and there is room for it on the left side of the breakers. However, I cut one of the incoming grounding wires a little too short to reach over to the left side and it would be easier to have the grounding bar on the right side. It's my understanding that it is not advisable to splice grounding wires in the box.

Can I use the existing neutral bar on the right side as a grounding bar, and since it is isolated can I just jump it to the box? I'd then install a new isolated neutral bar on the left side.

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    Branch circuit grounds can be spliced. Only panel grounding conductors must be continuous.
    – isherwood
    Oct 12, 2022 at 15:18
  • I'm curious, isn't the answer definitively yes? Is there any inherent difference between the two bars or is it only when one of them is mounted on plastic and used exclusively for neutrals that it becomes a "neutral bar"? So if you do what you suggest, your question vanishes. You no longer have a neutral bar used as a ground bar, you just have a ground bar. No? Although I think sometimes neutral bars are bigger because of the rules about doubling up, but in a 4-position box that should not be a factor.
    – jay613
    Oct 12, 2022 at 16:10
  • The existing bar is for neutral since it is isolated. So if I make it a grounding bar I have to jump it to the box..right? And then install a new isolated neutral bar on the other side. The ground wire that is too short is a thick gauge bare copper wire connected to two grounding rods at the sub-panel. This is in addition to the grounding wire that comes from the main supply panel. Can I splice a smaller gauge bare wire to the ground rods thicker wire, or a piece of insulated stranded wire, of which I have the same size? Or just go with my plan to swap bars.
    – Commander David
    Oct 12, 2022 at 16:32
  • My interpretation of the excellent answer below is that you cannot splice that particular wire. My point above is that if you move the isolating plastic mount to the other side, there is no longer a question to ask. The two bars differ only in the way they are mounted. They don't have memory. You will have a neutral bar on the left and a ground bar on the right, you will not have a "neutral bar used as a ground bar". Just make sure all the other grounds and neutrals can reach the opposite sides.
    – jay613
    Oct 12, 2022 at 17:05

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If you do as you propose (make the existing isolated neutral bonded to case, and used only for grounds) and install a new isolated neutral for the actual neutral wires, that is fine for a sub-panel (which this seems likely to be.)

As commented by @Isherwood, most grounding wires can be and regularly are spliced - the ones required to be unspliced (or irrevocably spliced/welded) are specifically the the heavy grounding wires connecting the panel to the grounding electrode system.

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  • The ground wire that is too short is a thick gauge bare copper wire connected to two grounding rods at the sub-panel. This is in addition to the grounding wire that comes from the main supply panel. Can I splice a smaller gauge bare wire to the ground rods thicker wire, or a piece of insulated stranded wire, of which I have the same size?
    – Commander David
    Oct 12, 2022 at 16:14
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    Nope, that's the one that needs to be unspliced, or spliced in a permanent fashion. You might be able to shift some slack, if you left any slack, but most folks that cut wires too short are the same folks that don't leave any slack, so you likely haven't got any available.
    – Ecnerwal
    Oct 12, 2022 at 16:35
  • Thanks. I'll go with configuring/jumping the existing neutral bar as ground and install a new isolated neutral bar.
    – Commander David
    Oct 12, 2022 at 16:44
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No. Accessory neutral bars are not a thing.

You can fit as many accessory ground bars as you please to. But only the factory provided neutral bars can be used, unless the panel instructions or labeling calls out a specific alternate neutral bar. UL approves the labeling and instructions as part of the UL Listing, so if the label says you can use the accessory, you can. Otherwise no.

However, you can improvise ground bars.

On a service panel, the metal chassis of the panel is grounded and is a valid ground current path. As such, you can attach the wire to the metal chassis.

The easiest way is to take an accessory ground bar (or a simple 1-hole lug) and bolt it to the metal chassis where it will fit.

  • If you scrape off the paint at point of contact, you can do this to the side with a drilled hole, bolt and nut.
  • If you're into workmanship, you can drill your own hole and tap it for a #8-32 NC or #10-32 NF machine screw, thus using the panel itself as the "nut". That is sufficient for electrical contact due to the fine -32 thread pitch.
  • Do not put a mounting hole on a knockout.
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  • On an outdoor sub panel with grounding rods can I bond the grounding rod's wire directly to the inside of the metal electric panel, and then attach all the other ground wires to a grounding bar. The issue I'm having is the existing grounding rods wire is too short to reach the grounding bar in the upgraded panel I'm installing, and I know I cannot splice it.
    – Commander David
    Oct 15, 2022 at 8:26
  • Yes, you can attach the wire to the metal chassis @Commander. I would just use an accessory ground bar (like $6). Either bolt it to the panel as I described above, or just take advantage of the fact that it has 2+ lugs and run a second ground wire to wherever it's gotta go.
    – Harper - Reinstate Monica
    Oct 15, 2022 at 19:36

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