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Sub-panel Bonding/Grounding Question with Meter Pedestal and 3 Panel Architectur

Sub-panel Bonding/Grounding Question with Meter Pedestal and 3 Panel Architectur


Old 12-14-15, 03:08 PM
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Location: USA
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Sub-panel Bonding/Grounding Question with Meter Pedestal and 3 Panel Architectur

Sorry if this is a redundant question, but it is a bit atypical, but common in rural areas of Vermont. I will call this a "3 Panel Grounding / Bonding Question."

My first panel is located near the telephone/power company pole. This panel takes 2 hots and 1 neutral from the grid and connects it to a main 200 amp disconnect combined with a meter pedestal. This is only 10 feet from the pole. In this panel, the neutral conductor bus bar is BONDED to the ground bus bar which is then grounded with 2 redundant copper clad grounding rods.

From there, 2 hots and 1 neutral cable goes to the main 200 amp panel in the basement of a new house (It's big, 350 mcil aluminum cable that was a bear to install. Installed in conduit underground. 350' run. 200 amp capacity). Per my research, the neutral line and bus bar are NOT BONDED to the ground bus bar. Also note that the power cable passes through a manual transfer switch first before going to the main 200 amp panel (but this is not in question). That is just a pass-through switch to switch between grid and generator. The main issue is that ground and neutral are NOT BONDED in this second panel as they are already bonded at the meter pedestal / main disconnect.

From this 2nd main panel, I have a 100 amp double pole breaker that goes underground to a cabin 150' feet away. The cable has only 3 conductors (2 hots and 1 neutral). So it has no dedicated ground.

At the 3rd panel, the 2 hots and 1 neutral are connected to the sub-panel. Neutral and Ground bus bars are mixed (i.e. some bare copper are in the neutral bus bar and vice versa). The neutral and ground bus bars are BONDED and there is NO dedicated grounding rod at the cabin. Note that this cabin was the original building and is "old wiring." The new house is all new. What I did was reuse the old service cable that went from the pole to the cabin as the new house to the cabin circuit. I believe this panel (in the original cabin) had bonded neutral and ground as there was NO (yes, NO) disconnect at the pole originally. The service came directly from a meter hung on the pole to the panel in the cabin. It didn't even have a 100 amp disconnect in the panel! All hot!

But now that we have a new architecture, my questions are the following:

1) Is this setup code-compliant as-is? I believe everything is 100% correct up to the cabin. It's just that the cabin is now part of a different system.
2) If it isn't correct, what needs to be done? Do I need to unbond neutral and ground bars and clean up the ground and neutral wires in the cabin and run a dedicated ground wire 150' back to the house as well as drive a dedicated ground rod at the cabin? If this were a blank slate, I think that is what code would require. But, right now, I am essentially treating the cabin as a primary service run and my house is acting like the power company source (where I simply have 2 hots and a neutral) and since that source is not bonded, the cabin needs to be bonded.

Please note that all the electrical works as it did...but my concern is how safe this setup is and what would happen if various faults were to occur.

Many thanks...Picture include for help...Name:  3 Panel Architecture Grounding and Bonding.jpg
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Old 12-14-15, 03:27 PM
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Note: moved this to a new thread as it is a separate question

Dozer, welcome to the forum. What year was all of this installed? Do all of the buildings, pedestals and so forth have conduit?
Old 12-14-15, 03:52 PM
Join Date: Mar 2010
Location: USA
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From the first panel (meter pedestal) to the second panel (main house), is the conduit metal or plastic?

It would not be code compliant with plastic conduit since you need a separate grounding conductor here.

How far is the cabin from the utility pole? Using your new routing 150' from the main house you will need to run a new #2 gauge copper (or O gauge aluminum) line with ground as a 4'th conductor (#6 copper or #4 aluminum). I gave you about 2% voltage drop from main house to the cabin since you already suffer some voltage rop from the meter to the main house.

Last edited by AllanJ; 12-14-15 at 04:34 PM.
Old 12-14-15, 07:46 PM
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This sticky may help answer some of your questions.


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