Old subpanel bonded to neutral instead of grounded?

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rotax

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I'm adding a well pump circuit to an existing electric system.

There is an electric meter and main breaker panel in Barn A. There is an 100A breaker in the panel and 3 wires , (2 hots, one neutral?) are buried underground to feed a panel in Barn B. I ran a NM cable from that panel (defined as a subpanel?) to a well pump switch inside Barn B.

Is the existing subpanel properly grounded? All the neutral and ground conductors are screwed to the single busbar which is bonded to the enclosure

some related discussion with the gist that subpanels should have their own ground electrodes and not be bonded to neutral, at least for new work

 

wwhitney

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Every structure with an electric panel needs a grounding electrode system. So Barn B needs one, e.g. 2 ground rods, each 8' in the ground and at least 6' apart.

The current NEC requires a feeder to any structure to include an EGC (ground or grounding conductor), but older versions allowed the omission of the EGC if there is no other metallic path between the structures (cable TV, telephone, metal water line, etc). Feeders so installed can remain in use, as long as no other metallic path is created.

Every structure supplied without a grounding conductor (i.e. by a service from the utility, or by an old feeder without a ground) needs to have a neutral-ground bond. Which you have in Barn B, as you have a common neutral/ground bar bonded to the electrical panel case.

Cheers, Wayne
 

rotax

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Thanks, Wayne. If barn B has an electrode system it would be obvious to see a big ground conductor entering the panel somewhere? I noticed the barn has a metal roof and a woven lightning cable running to the roofline. Whatever it is hooked to is buried.
Is this buried in metal conduit?
I don't think so, it comes out of the dirt isleway in a pvc conduit
 

rotax

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Looking at the big picture, the issue here is mitigating the issue of the feeder wires getting damaged? If the installation is correct the components would be safe to troubleshoot after a power outage caused by a feeder disruption.

In my case, if feeder neutral to barn B gets disrupted, the power would go out but the panel and other components could be hot and dangerous to troubleshoot for the unsuspecting handyman?
 

rotax

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What I gather from post #2 is that the configuration I see at barn B was correct for the time it was installed and I don't need to change things now.
 

wwhitney

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What I gather from post #2 is that the configuration I see at barn B was correct for the time it was installed and I don't need to change things now.
True if Barn B has a grounding electrode system. If not, you need to add one.

Cheers, Wayne
 
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