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In the photo below of the top of my main panel, wire A is clearly not in a good spot. Perspective in the photo is distorted, it's actually about 1-1/2" from the mains, but still ... Anyway, at the left, not visible, it goes to a ground screw in the panel enclosure. If the incoming service neutral is bonded to the enclosure some other way then wire A is clearly unnecessary -- and even if needed it doesn't need to go across because both sets of bars are connected to the incoming neutral, and hence to each other.

Any good way to find out if the enclosure is bonded some other way, other than shutting things down, removing the neutrals / grounds (they need to be neatened up anyway), and looking for a bonding screw? Would it be normal to have an older main panel where bonding of the enclosure was not built in?

If the enclosure is not bonded then it clearly should be but I'm thinking a piece of bare #12 is not the way to do it. I couldn't figure out what size wire is required by code for bonding a main panel enclosure. Does it follow the EGC bonding table in 250.66, which would require #4?

main panel breaker and ground / neutral bars

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  • In a main panel neutral and ground are to be bonded(connected) together. Depending on how the ground/neutral buses are attached to the panel, sometimes they use a wire("A") to bond them, and sometimes just the metal of the panel. Even at an 1 1/2 inch "A" does not look to be in a good place, those hots have no overload protection so will keep pumping out the power if shorted till flames/smoke/house burning down happens.
    – crip659
    Sep 4, 2022 at 15:42
  • @crip659 totally agreed that "A" has to go. The question is do I need to remove it or replace it, and if I replace it, with what? The neutral / ground buses are definitely bonded together, you can sort of see at "C" that they are mounted to the same metal bracket. What I can't figure out is whether they are bonded to the enclosure, other than via wire "A".
    – trawson
    Sep 4, 2022 at 15:51

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Danger Will Robinson!

That bare neutral cross-wire marked "A" is dangerously close to non-fused "hot lugs". That really needs to be removed.

Since the wires were inserted from the inside, and definitely collided with the hot terminals while being inserted, it's clear it was installed before the panel was energized. Even if there was a need for that wire, it should have been much larger, inserted from the outside, and insulated or routed an entirely different way.

They did it that way because they also wanted to bring in a regular neutral from the outside, and had the demented idea that this isn't "double-tapping". Well, it is. And loosening that screw to maintain that neutral would result in wire "A" moving! And hitting the hot terminal!

So no, you need to call the power company and ask for permission to pull the meter to correct this. Tell them a neutral wire is dangerously close to a hot terminal and needs to be moved Right Now. It's a trivial repair and they shouldn't stand on formalities and require permit/inspection. Often they can do a remote/virtual meter pull where they shut off the smart meter remotely. Check before working!

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  • Love the title! However, the problem here is that the photo has distorted things quite a bit. Can I blame the lens on my cell phone camera? I went back in the panel and double-checked, wire “A” is about 2” above the hot lugs and about 2-½” above the neutral lug. It's not connected to the neutral lug at all, though I see why it looks like that from that little dip. It just goes across between the two bus bars. I'm not at all saying it's a good idea, but it isn't what it looks like. I am used to working inside the panel and I'm comfortable with carefully removing the part that goes across.
    – trawson
    Sep 4, 2022 at 23:24
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I couldn't figure out what size wire is required by code for bonding a main panel enclosure.

I found the answer to this part of the question (hope this is the right way to post it). Table 250.122 Minimum Size Equipment Grounding Conductors says for a panel protected by a 200 A OCPD the EGC bond to the enclosure must be #6 or larger.

I'm not sure if I need this yet because I haven't figured out if the enclosure is bonded to the neutral bus by the manufacturer via a screw, but if not at least I know what is required.

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