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Peculiar Panel


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Had one yesterday that I've never seen in a private residence in more than 16 years; a breaker-type panelboard with a pull-block main disconnect.

It was kind of overkill. A tiny little 1600 square foot house. The grounded conductor between the home and the pole was a heavier-than-normal cable wrapped directly around the insulator, instead of being held with a clamp, the service entrance cables are 3/0 copper and the panelboard is rated for 200 amps. The cartridge fuses in the pull-block though are 125 amps - which I'm certain is more than enough capacity for this little home.

I figured that the panel was commercial grade. 'm thinking that maybe this home's original builder/owner was an electrician of some sort - thus the overkill.

Found every grounded conductor sharing a bus terminal screw with it's equipment grounding conductor. I know that's been prohibited by the NEC since the "60's" but this house was builtin 1960; so I have no idea whether it was a mistake on the part of the original electrician or it was at the time perfectly acceptable. I have to confess that after 52 years I'm having a hard time with the idea that doing so was somehow dangerous, regardless of the reasons for the rule.

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ONE TEAM - ONE FIGHT!!!

Mike

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One can't get that inner cover off to get a look at the connections adequately without pulling the block. I understand the concern but I'd rather have it fail when I pull it than let the customer buy the home move in and then the first time he pulls it it breaks in his hand. At least this way he knows that it wasn't broken at the time of the inspection and if it had cracked or fallen apart I would have simply written it up as failed under testing.

ONE TEAM - ONE FIGHT!!!

Mike

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Same here. Not common, but not a rarity.

I'd never pull a bakelite block; had one fall apart in my hands years ago, and guess who paid for the entirely new service... And yes, it is our fault if we break it.

Isn't the "fuses are more reliable than breakers" argument outdated? Maybe at one time, but new breakers are as good as fuses, aren't they?

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. . . Found every grounded conductor sharing a bus terminal screw with it's equipment grounding conductor. I know that's been prohibited by the NEC since the "60's" but this house was builtin 1960; so I have no idea whether it was a mistake on the part of the original electrician or it was at the time perfectly acceptable. I have to confess that after 52 years I'm having a hard time with the idea that doing so was somehow dangerous, regardless of the reasons for the rule. . . .

The rule has been around since the late '30s. It was definitely incorrect in 1960. I agree that it's not dangerous as long as the electrician managed to get both wires secured fastened.

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I'll chime in. the grounding conductors are one size smaller than the neutrals. Typical for the age, but another reason not to have them both under the same screw.

I would not pull the fuse block, but then I would not be able to report the fuse size either. It would have been wrong to guess the size by the cable.

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Thanks for your responses.

Jim,

Thanks, I'd been remembering it as since the '60's. So much for the theory that my brain has yet to turn to putty.

It wasn't recycled; it's definitely original to the home. My first glance at the thing told me it was commercial grade. I was just really surprised to see such a large commercial panel in such a small home.

There were other quirky things about the home that told me the original owner might have been the builder or, perhaps, a Boeing engineer. He'd gone oversized (for this area) on the rafters and ceiling joists; used plywood for roof decking and sheathing instead of the ubiquitous 1x T & G; used a plank-and-beam floor with closer-than-normal beam and post spacing (As if he were bound and determined to have the most solid/quietest wood floor possible - which it seems to be), all copper plumbing in a neighborhood where everything else is galvanized steel, a hydronic heating system instead of forced hot air.

To those of you in parts of the country where use of this stuff is standard, it would seem like a perfectly normal house but for this region it just screamed obsessive-compulsive original builder/owner.

Kurt, I appreciate what you say about the split bakelite block - I've had those too. Actually, I've had panels where the block was split and was still being used - because they could do so, I suppose. The SOP doesn't prohibit us from pulling a block, it just doesn't require it. We can all of us exceed our SOP's when we feel it's necessary and are willing to do so - it's a judgment call and when we do it we have to be sure to use our common sense. We all have to make those calls sooner or later.

ONE TEAM - ONE FIGHT!!!

Mike

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I had something similar last week on a 1959 sfr home, also a first for me. In this case it was a large pull block at the exterior meter. From there were two conduits to two widely separated and different 125-amp breaker panels, one at the exterior by the front door and the other in a basement bathroom (handy for flipping breakers while showering). Both of those panels had co-mingled grounds and neutrals along with all sorts of other electrical crap. The home was occupied, which gave me a good excuse for not pulling the block, not that I really needed one.

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  • 1 month later...

When I was first getting started I was hanging out with some friends up at the local lake. One of their friends was an electrician. I asked him about the doubled up neutral thing. He used to not worry about it till one time he had to replace a guys computer because of a loose neutral situation that he was responsible for.

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