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Square D panel bonding


inspectorwill
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Newer Square D main panel installed on a 1925 home. A separate ground bus was installed (for some unknown reason) but no bond to the floating neutral terminals. I couldn't determine whether the neutral is bonded to the enclosure at the service. The panel label has faded and peeled. Is anyone familiar with this type of panel? My recollection is that this type of panel can be used as a main or sub and requires a bond from the enclosure to the neutral. I have included an overall pic and a close up of the neutral bar bond to the service neutral.

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The schematic on the left side of the first picture looks as if it's readable. It should show the location of the bonding screw, if there is one.

What's the #6 (or #8) bare copper wire that lands on the upper left side of the left neutral terminal? Is that the grounding electrode conductor?

What's with the enclosed upper part of the panel? Is the meter up there or is this a Canadian style panel with the upper section separately enclosed?

- Jim Katen, Oregon

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Hi,

I don't see a service grounding conductor connected to that ground bus; so, if that heavy conductor is your service ground you must bond the neutral buses to the panel enclosure. Look at the second picture; you have a square hole on the left and a U-shaped slot at the edge of the strap on the right. The U-shaped slot is where the green bonding screw needs to be.

Was this panel one that an electrician salvaged? Those huge open knockouts at the bottom of the panel look like they used to house myers hubs with conduit.

ONE TEAM - ONE FIGHT!!!

Mike

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You are saying you couldn't access the service panel so this is a subpanel, right?

That explains why they are keeping the grounds away from the neutrals.

In which case, that large bare wire needs to be removed from the neutral bus, I think. Also, there are at least 3 missing knockouts. That is enough trouble to call for an electrician to evaluate the whole installation and repair at least those items.

If that is actually the main disconnect, it needs the bonding screw, so it still needs an electrician. Are all the circuits 120 V? I don't see any tiebars or double breakers.

BTW, a Canadian would never create a mess like that. [:)]

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The english portion of the schematic had peeled off. A portion was legible but in spanish and I no habla. The large bare copper wire is the grounding electrode that goes to a ground rod. This was the main panel and the top part of the panel is the meter. The panel did look salvaged to me also because of the large knockouts at the bottom and the installation appears amateurish. Because there was no obvious bonding screw or bond connection between the ground bus and neutral bus, I am confident the bond doesn't exist. Thanks for all the input.

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Hi,

Glad we could help; but, please, get the terminology correct. That big bare wire? It's not a grounding electrode, it's a service grounding conductor. The rod that 's driven into the grount that it's connected to? It's not a ground rod; it's a service grounding electrode.

It's important to learn this stuff and knowing it might one day serve you well when you're sitting in a courtroom testifying against Larry, Daryl and Daryl.

ONE TEAM - ONE FIGHT!!!

Mike

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That big bare wire? It's not a grounding electrode, it's a service grounding conductor. The rod that 's driven into the ground that it's connected to? It's not a ground rod; it's a service grounding electrode.

I've only heard/ seen the ground wire referred to as a Grounding Electrode Conductor (GEC), and the ground rod as the Grounding Electrode.

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That big bare wire? It's not a grounding electrode, it's a service grounding conductor. The rod that 's driven into the ground that it's connected to? It's not a ground rod; it's a service grounding electrode.

I've only heard/ seen the ground wire referred to as a Grounding Electrode Conductor (GEC), and the ground rod as the Grounding Electrode.

Those are the correct "school terms." The reality is that few people actually refer to them that way in the field. It's useful to know both the school terms and the street terms so that you can understand and be understood in both environments.

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"It's important to learn this stuff and knowing it might one day serve you well when you're sitting in a courtroom testifying against Larry, Daryl and Daryl."

Hey, Mike, let's not knock Larry, he's a friend of mine! Seriously, though, I've worked for Bill Sanderson at his house and with him on HBO. Way smarter than Larry and a really nice guy.

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