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Old 08-07-2012, 09:36 PM   #1
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Grounding 400a service to 2-200a panels


I have a grounding question. I am installing 400a service to my new home. We ran 350MCM wire underground thru 3" conduit from the 2ndary terminal (moped) to the house into a 320A Cooper B-Line meter. From the meter we ran 2 sets of 4/0-4/0-2/0 thru the wall to 2-200a breaker panels ("standard practice", according to my electrical supplier). The ground wire (#4Cu bare) from the grounding rods comes up from the ground and we're curious if there has to be a special splice connecting the ground wire to each breaker panel or can we run thru one breaker panel to then next, say by connecting the ground wire to a ground bus on one panel and running that thru to the next with #4Cu bare or #6Cu in conductor. Different electricians are suggesting different methods and the electrical inspector is unsure, but seems to be leaning towards the "special splice". Any feedback would be appreciated.

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Old 08-08-2012, 05:02 AM   #2
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Grounding 400a service to 2-200a panels


You can do it one of 2 ways.

Take a #6 (#4 since you have it already) from one panel through each rod, then do the same for the other panel (use one clamp for each connection unless listed for multiple) or take a #6 through each rod to the first panel and a #4 jumper from panel to panel.

The connection should be made as close as possible to the grounded conductor. Some panels have a lug where the neutral connects to terminate the GEC. If not, I usually terminate on the neutral bar just below where the neutral connects.

Keep in mind, if you think about putting multiple wires under one lug because it fits, make sure that the lug is listed for multiple connections. Usually it isn't.

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Old 08-08-2012, 05:43 AM   #3
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Grounding 400a service to 2-200a panels


There's obviously other methods of doing this as I've just learned on another thread. These just work for me
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Old 08-08-2012, 06:00 AM   #4
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Grounding 400a service to 2-200a panels


Just bond the two disconnects together and out of one of them hit your grounding electrodes.
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Old 08-08-2012, 11:15 AM   #5
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Grounding 400a service to 2-200a panels


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I have a grounding question. I am installing 400a service to my new home. We ran 350MCM wire underground thru 3" conduit from the 2ndary terminal (moped) to the house into a 320A Cooper B-Line meter. From the meter we ran 2 sets of 4/0-4/0-2/0 thru the wall to 2-200a breaker panels ("standard practice", according to my electrical supplier). The ground wire (#4Cu bare) from the grounding rods comes up from the ground and we're curious if there has to be a special splice connecting the ground wire to each breaker panel or can we run thru one breaker panel to then next, say by connecting the ground wire to a ground bus on one panel and running that thru to the next with #4Cu bare or #6Cu in conductor. Different electricians are suggesting different methods and the electrical inspector is unsure, but seems to be leaning towards the "special splice". Any feedback would be appreciated.
What NEC are you using?
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Old 08-08-2012, 12:08 PM   #6
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Grounding 400a service to 2-200a panels


We run the water ground to one panel, the ground rods to the other, run a jumper between the two panels, and split bolt the jumper and each of the grounds above the panels.
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Old 08-09-2012, 09:27 PM   #7
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What NEC are you using?
Fascinating question. Which would YOU suggest? That would be most helpful, thanks for your input!
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Old 08-09-2012, 09:49 PM   #8
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Grounding 400a service to 2-200a panels


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Fascinating question. Which would YOU suggest? That would be most helpful, thanks for your input!
You don't seem to understand. You cannot CHOOSE which version you use, your state/community chooses for you. You need to find out which code cycle your area is under.
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Old 08-10-2012, 10:06 AM   #9
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Grounding 400a service to 2-200a panels


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Originally Posted by Kingb
Fascinating question. Which would YOU suggest? That would be most helpful, thanks for your input!
The version adopted by your governing body.
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Old 08-12-2012, 02:31 PM   #10
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Grounding 400a service to 2-200a panels


My jurisdiction required me to make one continuous loop.

I started in panel A, outside, thru the connector for grounding rod #1 thru connector on grounding rod #2 back inside, to panel B.

It had to be one piece of wire, no splices permitted.
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Old 08-12-2012, 02:53 PM   #11
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Grounding 400a service to 2-200a panels


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My jurisdiction required me to make one continuous loop.

I started in panel A, outside, thru the connector for grounding rod #1 thru connector on grounding rod #2 back inside, to panel B.

It had to be one piece of wire, no splices permitted.
Haha. What he wants and what is required are not the same.
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Old 08-12-2012, 02:54 PM   #12
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Grounding 400a service to 2-200a panels


I've seen a couple posts from people in that area stating the same thing. It may be some sort of local thing.
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Old 08-12-2012, 02:57 PM   #13
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Grounding 400a service to 2-200a panels


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I've seen a couple posts from people in that area stating the same thing. It may be some sort of local thing.
Some sort of local confusion.
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Old 08-12-2012, 03:36 PM   #14
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Grounding 400a service to 2-200a panels


Quote:
Originally Posted by AndrewF View Post
My jurisdiction required me to make one continuous loop.

I started in panel A, outside, thru the connector for grounding rod #1 thru connector on grounding rod #2 back inside, to panel B.

It had to be one piece of wire, no splices permitted.
The wire between the ground rods in either direction is just a bonding wire to augment the first ground rod, again, in either direction... not a grounding electrode conductor.

Of course, I would have made it continuous to save two acorns.
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Old 08-12-2012, 10:26 PM   #15
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Grounding 400a service to 2-200a panels


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Fascinating question. Which would YOU suggest? That would be most helpful, thanks for your input!

KingB.,

What state or provice you are in ?? once you tell us what state or proviance we will know the code cycle due there are few differnt verison to use.

Merci,
Marc

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