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My house was built in 1975 and I pretty obviously have a "Rule of 6" GE main panel (the meter is above this)

Main Panel

My father-in-law (who has taught me a great many DIY things) swears that the neutral bus here is done wrong. (I didn't dare open the top where the meter is, but the bus extends above so I presume the service neutral connects up there.) I won't say he's outright wrong, but with this being the main panel, it looks acceptable to me (inasmuch as a panel of this age can be). I suspect the thick bare ground goes to a rod inside the slab, but I can't open the wall either to check, and I have no ground rods outside the box.

Is this passable, or is the only acceptable way to bond through a binding screw?

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    Can you post photos of the labeling on the inside of this box's door please? – ThreePhaseEel Mar 12 at 12:46
  • Is that a white and green wire under the same wire connector? Could you get a better picture or description of what's going on there? – NoSparksPlease Mar 12 at 13:56
  • It looks like they used the box as a junction box and the green/white/black wires are wire nutted in the upper right to a cable (barely visible) behind the conduit on the lower right. Doesn't look like there are any connections to breakers in the box, but it would be good to verify. – George Anderson Mar 12 at 14:46
  • The wires on the side are from a 15A 240v breaker in a subpanel. I suspect they moved said breaker from this panel to add the subpanel. They then ran EMT back to this panel to connect to the existing EMT that runs to the pool pump. – Machavity Mar 12 at 15:02
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It's bonded, alright

Meter-main boxes like yours have their neutral bars permanently bonded to the case at the factory, and thus have a notation on their label saying that they are "suitable only for use as service equipment" (emphasis mine). In your case, this is done through the mounting of the left-hand bar; if you look closely at it, you'll notice that there is no insulator between it and the case, unlike the neutral bars on a typical loadcenter, which are mounted on insulators (whether they be part of the backpan the busbars are attached to, or separate standoffs).

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The heavy copper wire might more likely connect to a metallic water main near the place where the main enters the house.

A bonding screw is used to short/bond an insulated neutral bar to the grounded chassis of a panel. (That's not the only way to bond an insulated neutral bar to ground: a jumper wire is another reasonable solution.)

So one question is this: is that neutral bar at the left edge mounted in a way that electrically insulates it from the metal box? If it's not insulated then this panel has an implicit ground-neutral bond simply by virtue of landing all the grounds and neutrals on the same bus bar.

I note there are some white and green wires on the right side of the panel whose terminations aren't visible. They should be connected to another bus bar, also mounted so as to be electrically connected to the metal box.

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  • I strongly suspect it's not an insulated bar (which is what concerned my father-in-law). Without a cutoff, I'm not inclined to poke in there and find out. – Machavity Mar 12 at 14:16
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Yes it looks like a properly bonded 6 disconnect service.

One easily corrected problem is alien breakers. You are only allowed to use breakers that are NRTL Listed/Classified for your panel. There is often some confusion about what the current brand is for brands that have been acquired by others, but I have never seen a panel Listed for both Bryant (now Eaton) and GE.

I am a little concerned with seeing only one insulated neutral on the grounded neutral bus. It hope it is the only feed to a subpanel.

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    Yep, that insulated neutral feeds a subpanel. It was installed well after the main panel. And some electricians have noted the breaker mismatch as well. There's some other potential issues to boot. I'm mulling a full panel replacement (for obvious reasons) but this disagreement seemed like a good question to bring here. – Machavity Mar 12 at 14:14

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