Electrical question

[planomustang]

I just got the electricity run to my barndo. The Coop required that I install a master shutoff below the meter, then run underground cable to the main panel in the barndo.

In the master shutoff, the neutral bar is grounded to an 8' copper rod.

I think this configuration makes the main panel in the barndo become a sub-panel. If that is true, then I should not bond the neutral bar and ground bar in the main panel.

Is that correct?

[125Dad]

Correct the panel in the house is a sub-panel. If I read this correctly there for you will need to pull 4 wires from first panel to sub and keep the neutral and ground isolated from each other at sub-panel end but bonded at first panel.

What your calling master shutoff has a breaker correct?

[planomustang]

Correct the panel in the house is a sub-panel. If I read this correctly there for you will need to pull 4 wires from first panel to sub and keep the neutral and ground isolated from each other at sub-panel end but bonded at first panel.

What your calling master shutoff has a breaker correct?

Yes, the master shutoff is a breaker. I only have three wires that run from the master shutoff to the main panel. Two 4/0 120 legs, and a 2/0 neutral. This is the way the Coop instructed me to install it. I don't have the fourth wire.

[Mrsailfish]

Your neutral and ground are the same at the master shutoff
It will be isolated from there on. This is were the fourth wire comes in
Yes

[planomustang]

Your neutral and ground are the same at the master shutoff
It will be isolated from there on. This is were the fourth wire comes in
Yes

It is a 300' run from the master cutoff to my main panel. The wires are in conduit and already buried. Running a fourth wire back to cutoff is something I would like to avoid.

In the main panel, do I have the option of grounding it locally, and keeping the neutral/ground unbonded in the main panel?

[Mrsailfish]

I can’t recommend you to do it wrong. I would not want to feel bad if you burned something down. Just wondering why the ground was not pulled to start with? I know some people will say go for it and all will be good, this is true until you have a problem and the system does not work right. I have been an electrician for over thirty years and I have seen it work, and I have also seen it start fires.

[planomustang]

I can’t recommend you to do it wrong. I would not want to feel bad if you burned something down. Just wondering why the ground was not pulled to start with? I know some people will say go for it and all will be good, this is true until you have a problem and the system does not work right. I have been an electrician for over thirty years and I have seen it work, and I have also seen it start fires.

The electric coop required the master cutoff at the meter, and their diagrams did not show the wiring from the master cutoff to the main panel. When I purchased my wire from them, they gave me three wires, not four. I did not know about the need for a ground wire between the cutoff and main panel, until now.

From my research, the code requirement for the separate ground to sub-panels went into effect in 2008, so this is relatively new.

Basically, I am trying to find a safe alternative to burying another 300 feet of wire.

[Mrsailfish]

In this situation, I would unbind the neutral at the main cutoff, I would then drive a new ground rod at the barndo and bond the neutral there. I would also come off of the neutral and run about a #2 copper wire and bond it to the building steel. This to me would be the best thing and it would be like the power company running the power all the way to the bardo and would eliminate the double bond issue.

[planomustang]

In this situation, I would unbind the neutral at the main cutoff, I would then drive a new ground rod at the barndo and bond the neutral there. I would also come off of the neutral and run about a #2 copper wire and bond it to the building steel. This to me would be the best thing and it would be like the power company running the power all the way to the bardo and would eliminate the double bond issue.

Thanks for that suggestion. I was nearly there, on my own.

The master cutoff and the main panel both contain a 200 amp main breaker. With your suggestion, the main panel breaker would throw if I drew more than 200 amps in the building, due to a severe failure.

I am trying to understand the risk of un-bonding at the master cutoff. Is there a scenario where the master cutoff breaker should throw before the main panel 200 amp breaker, but the un-bonding at the cutoff would prevent the cutoff breaker from throwing?

I am not suggesting to keep two bonds. That is a no-no.

[meltingfeather]

I am trying to understand the risk of un-bonding at the master cutoff.

I don't see a risk. You have two different ground points with the possibility of a potential between them, but there should not be a conductive path between them.
You essentially have a ground rod driven for equipment ground at the cutoff but otherwise it's as if the utility brought power to your building.

[texasforever]

If you bond at main and just drive in a ground rod at subpannel depending on what soil you have around your house there’s a good chance of still having a solid ground connection between both of the panels due to the conductivity of your soil. All of the suggested ways will work just a matter of ease and ability to troubleshoot further down the line.


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[125Dad]

I can’t recommend you to do it wrong. I would not want to feel bad if you burned something down. Just wondering why the ground was not pulled to start with? I know some people will say go for it and all will be good, this is true until you have a problem and the system does not work right. I have been an electrician for over thirty years and I have seen it work, and I have also seen it start fires.

This is good advice.

[125Dad]

To avoid pulling a ground in the conduit would the correct thing to do would be remove the master shut off and install a splice box.

I believe leaving the breaker at the pole and doing the ground at the sub panel could cause problems with all the breakers to trip in the sub panel. The fault may not find its way back.

I would highly recommend you do it correctly. I understand not what you want to hear.

[planomustang]

ddd

After spending several days researching this on the internet, here is the best quote I found:

"This question comes up often, and there are plenty of experts on the subject. The problem is that all the experts have different answers."

I just called the Wise Electric Coop, and I talked to one of their engineers. He told me to leave the ground and neutral bonded at the master cutoff, which they require. The keep the ground and neutral un-bonded at my main sub-panel. Add a separate ground bar in the sub-panel, that is earth grounded at the barndo.