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Old 05-26-2009, 11:14 AM   #1
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Service Upgrade - Ground Bonding Question


So I am starting the 200 to 400 amp upgrade this week, and as I was strategizing last night, I realized I am not sure how to handle the copper ground.

I have 20' of solid copper line and two grounding rods.

I noticed the 400 amp meter socket has a spot for 3 copper grounding cables.

Do I run a solid copper wire from each 200 amp panel in the house to the Meter socket, and then from the MS to the two grounding rods, ensuring I do not splice it?

I ask because when I did this at my parents house (different county) and only a single 200 amp service, we ran the copper wire from the panel to the grounding rods, the meter socket never came into play.

----
The grounding electrode conductors, sized per 250.66, should originate at the meter or main breakers.

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Old 05-26-2009, 12:32 PM   #2
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Service Upgrade - Ground Bonding Question


The grounding electrode conductors,
Quote:
sized per 250.66,
should originate at the meter or main breakers.

Not the ground rods they only need to be #6 copper minimum.

If the inspector will allow the meter socket to be the grounding/bonding point to the grounded conductor (service neutral) then this will simplify the installation somewhat. Sometimes they require the grounding point to be accessible and may consider the meter socket to be unaccessible due to the seal. Simply run a #6 solid cu to the ground rods continuous without splice from the meter or continuous to the first ground rod add another clamp and then a piece to the 2nd rod.
Be sure the 3 lugs your talking about are not including the 2 lugs for the neutrals to your two inside 200 amp panels.

You do not have metal water pipes or a ufer ground??

Looks like this......


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Old 05-26-2009, 04:02 PM   #3
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Service Upgrade - Ground Bonding Question


I will call the inspector in the morning and see if accessible inside the meter is acceptable.

I am confused why you are suggesting I do not run a single line with no splits from grounding rod #1, to rod #2 on up to the meter socket.

Attached are two photos of the meter socket.

The GEC is bonded inside the meter socket to the neutral.

It is a milbank u-1129-0

The electric service comes into the attached garage where there are no water lines present. The house is served by county water via a copper line, but that comes in the basement which is not easily accessible from the garage.
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Old 05-26-2009, 04:22 PM   #4
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Service Upgrade - Ground Bonding Question


Here is what I asked.
----------------------

In regards to the GEC, is the meter socket a suitable grounding/bonding point for 400 amp service?

There will be two 200 amp panels side by side in the garage, opposite the meter socket. We’ll run solid #6 copper from panel A to the Meter socket and continue on to grounding rod #1 and then 6’ further to grounding rod #2.

We’ll run a single piece of #6 copper from Panel B to the Meter socket and terminate on the GEC terminal.
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Old 05-27-2009, 12:01 AM   #5
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Service Upgrade - Ground Bonding Question


Quote:
Originally Posted by AndrewF View Post
Here is what I asked.
----------------------

In regards to the GEC, is the meter socket a suitable grounding/bonding point for 400 amp service?

There will be two 200 amp panels side by side in the garage, opposite the meter socket. We’ll run solid #6 copper from panel A to the Meter socket and continue on to grounding rod #1 and then 6’ further to grounding rod #2.

We’ll run a single piece of #6 copper from Panel B to the Meter socket and terminate on the GEC terminal.

NO you have it wrong.

I am assuming 2/0 copper service entrance conductors feeding the two panels.


If you are allowed to bond the system to earth at the meter socket you will not bond the panels to the meter socket it will not be necessary. You bond at only one point to earth. That will either be the service equipment with main disconnect, meter socket or the grounded conductor where it enters the mast if an overhead service.

You are required to bond to the metal water pipe if it is in contact with the earth for 10 feet after it leaves the dwelling. You must connect to it within 5 feet after it enters the house or closer if local codes require it. Then you supplement that with 2 ground rods. No exceptions.

You do not run from the panels to the meter socket with your GEC.... the panels are bonded to the meter socket via their service neutrals, however the neutrals must be 1/0 cu mimimum...they should be. You have 3 lugs in the meter socket. From one lug run the #6 cu gec to the first ground rod unspliced. At the first ground rod you may terminate the gec to a single clamp. Then add another clamp then a #6 ground rod bonding conductor to the 2nd rod or you can run continuous from meter to rod 1 and then to rod 2. Two options. The section that is from the meter to rod 1 is the GEC and must be unspliced... after that you are simply running bonding conductors. You cannot however put two conductors under one clamp.

Use another lug for the GEC to the water pipe... it is sized to 250.66 note 1. This would be a #2 copper gec.

If you cannot bond from the meter socket let us know and we can tell you how to bond from the panels to earth for your grounding electrode system. The meter socket will not come into play in this method.
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Old 05-27-2009, 09:37 AM   #6
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Service Upgrade - Ground Bonding Question


Quote:
In regards to the GEC, is the meter socket a suitable grounding/bonding point for 400 amp service?
Sure they didn't put those lugs in there for nothing. For a single family dwelling the bond to earth can be the service grounded conductor where it enters the mast on overhead supplies. The meter socket. Or the service equipment where the first means of disconnect is located.
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Old 05-28-2009, 11:06 AM   #7
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Service Upgrade - Ground Bonding Question


Thanks guys. I think I understand now. So

I will be running AL SE cable from the meter socket to each panel. Approximate length of each SE run is around 5'.

If they do let me use the MB as the bonding point, is it an overkill or against code for me to still run a copper GEC to each panel directly for "added" protection?
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Old 05-28-2009, 12:02 PM   #8
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Service Upgrade - Ground Bonding Question


It would be a code viloation. If you bond at both the meter socket and the panels you will create parallel paths for neutral current and would have substantial neutral current on your copper gec between the panel and the meter socket. Draw it on paper and you will see the issue of doing this. There will not be any added property protection either.
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Old 05-28-2009, 12:29 PM   #9
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Service Upgrade - Ground Bonding Question


Quote:
Originally Posted by Stubbie View Post
NO you have it wrong.

You are required to bond to the metal water pipe if it is in contact with the earth for 10 feet after it leaves the dwelling. You must connect to it within 5 feet after it enters the house or closer if local codes require it. Then you supplement that with 2 ground rods. No exceptions.
Hmmh, this might pose a problem.

The closest water line, is PEX.
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Old 05-28-2009, 12:33 PM   #10
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Service Upgrade - Ground Bonding Question


Quote:
Originally Posted by Stubbie View Post
It would be a code viloation. If you bond at both the meter socket and the panels you will create parallel paths for neutral current and would have substantial neutral current on your copper gec between the panel and the meter socket. Draw it on paper and you will see the issue of doing this. There will not be any added property protection either.
I get it.

So ideally, I am only bonding the grounding rods to the Meter Socket and nowhere else. The visual diagram made sense and now I understand that aspect of it.

However, if I am not allowed to use the MS as the GEC bond, then I only bond ONE of the 200 amp panels to the grounding rods.

The 2nd panel will not have a GEC connection at all as it will rely on the neutral back to the meter socket back to panel A?
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Old 05-28-2009, 08:48 PM   #11
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Service Upgrade - Ground Bonding Question


Have you checked to see if your power company allows the meter socket to be grounded?
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Old 05-28-2009, 10:31 PM   #12
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Have you checked to see if your power company allows the meter socket to be grounded?
Negative. I'll ask the POCO engineer when he comes for a site visit next week. Thanks.
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Old 05-29-2009, 02:07 AM   #13
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Service Upgrade - Ground Bonding Question


Maybe I need to read this post again but I'm not following the logic in bonding the grounding electrode conductor to the meter can, which doesn't appear to have an overcurrent device from what I can tell. Grounding and bonding of the gear should take place at the point of service which is the main overcurrent device (or devices in this case). Connecting to the meter can is all fine and good but I don't see that it gets you out of landing the GEC at the disconnects in each panel.

As for the water service, it is to serve as a grounding electrode when available. With PEX it would be deemed not available and the rods would suffice....Unless your jurisdiction requires a UFER ground (depends on what NEC cycle they're on).
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Old 05-30-2009, 01:46 AM   #14
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Service Upgrade - Ground Bonding Question


Please read 250.24(A1) thru (A5). You are allowed to connect the gec to the 3 places previously mentioned. The meter can must be approved by the inspector and many times they will not allow it. The usual denial is based on the meter can not being accessible. In our area around KC it is unusual for residences to use the meter can but it is an excellent place to connect if allowed.

The water pipe is metal entering the house or so it appears and then converts to pex. This PEX doesn't exempt the gec for the water pipe bond.

2 things we need to know before continuing.

1.) Will the inspector allow the meter can for connecting to the grounded conductor for the GES?
2.) Does the metal water pipe meet the requirements of 250.52 (A)(1)
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Old 05-30-2009, 10:45 AM   #15
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Service Upgrade - Ground Bonding Question


I stopped at the supply house in my county (small county) to pick up some supplies and posed the question.

Their experience in this county has been to ground only (1) of the 200 amp panels to the grounding rods. The second panel neutral and GEC are bonded together in the second panel and since the neutrals are bonded together in the meter can and 1st panel, there are no parallel paths being created and as such, this type of install in my location would be approved.

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