cold water ground

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eddie722

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I have a 400 amp service with two main disconnects outside. One cold water ground is landed inside one of the 200 amp panels wich used to be the "main". Do I need to remove the cold water and land it in the disconnect or do I need to just run another cold water ground to the new panel?
 
If the service conductors were increased it is doubtful the original GEC is the correct size so relocating might not satisfy the Code (a 400 normally takes a #1/0). A 2nd GEC from the 2nd panel might be easier.
 
I would do something like this:

250.66%20Taps.JPG
 
Well what I have already is a 400 amp can, 2 sets of 2/O copper with 4 copper ground feeding 2 main breaker outdoor disconnects. These are feeding 2 200 amp panels. 2 ground rods wire in continuous loop between the two disconnects. The original cold water ground is landed in the original 200 amp panel. Do I need to remove it and land it in the disconnect? And do I need to run another cold water ground for the 2nd panel or disconnect??
 
As others have stated, you have options, one of which is shown in the sketch.
The bottom line is the GEC must orginate at the service per 250.24:
(1) General. The grounding electrode conductor connection shall be made at any accessible point from the load end of the service drop or service lateral to and including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.
Excatly where you connect (meter vs disconnects, etc) and if you run one or two conductors is a matter of preference (taking POCO requirements into consideration)
 
And to augment Gus' statement, in my area the interior of the meter socket is considered functionally "inaccessible" because access would require breaking the POCO seal which they view as trespassing of sorts.

Personally, I favor the 250.64(D)(2) route, especially in your situation. Just add in a second GEC and treat it as two 200A handles. :)
 
George if I'm reading this correct, the gec should land in the disconnects? So when all is said and done, ill have a ground rod and cold water ground in each disconnect and not the panels.
 
eddie722 said:
George if I'm reading this correct, the gec should land in the disconnects? So when all is said and done, ill have a ground rod and cold water ground in each disconnect and not the panels.
Click to expand...

That is one way of doing it. You can also jump the ground rods directly to the GEC from the water pipe if you don't want to land the rod GEC in the disconnect. Then that conductor becomes a bonding jumper.

1113918256_2.jpg
 
eddie722 said:
George if I'm reading this correct, the gec should land in the disconnects? So when all is said and done, ill have a ground rod and cold water ground in each disconnect and not the panels.
Click to expand...

Yes - if you insert a disconnect between the existing panel and existing meter socket location, then that existing panel is not an acceptable termination point for the GEC anymore.

Truthfully, I missed that detail in your description, so doing things along the (D)(2) route would require a pair of new GECs running to the pair of new disconnects.
 
One other thing to check -- is the water pipe really an electrode or are you just bonding it? If the pipe is metal in the earth for 10' or more, then you must make it part of the ground electrode system.

If not, then you are bonding it and bonding wires are permitted to be spliced. A #4 won't be large enough, so the wire is probably going to have to be redone anyway. But a 1/0 from the old panel would be OK if the equipment ground feeding that panel is also 1/0 or larger.

You could also consider becoming a plumber and changing the pipe outside to PVC or polyethylene.
 
suemarkp said:
One other thing to check -- is the water pipe really an electrode or are you just bonding it? If the pipe is metal in the earth for 10' or more, then you must make it part of the ground electrode system.

If not, then you are bonding it and bonding wires are permitted to be spliced. A #4 won't be large enough, so the wire is probably going to have to be redone anyway. But a 1/0 from the old panel would be OK if the equipment ground feeding that panel is also 1/0 or larger.

You could also consider becoming a plumber and changing the pipe outside to PVC or polyethylene.
Click to expand...

One of our local ahj's has a requirement that the first 10' of water pipe at the house (in the ground/dirt) be copper, then you can convert to plastic. this is so we have to run a GEC to the water main.
 
Every 400 amp service I do I use #2 copper for the GEC. I have a 400 amp meter then 2 -200 amp panels on each side of the meter. 1/0 is only needed if there are no service conductors- Note 2 of T. 250.66

I also run the #2 to the meter otherwise you need to get a gec to both panels.
 
Dennis Alwon said:
Every 400 amp service I do I use #2 copper for the GEC. I have a 400 amp meter then 2 -200 amp panels on each side of the meter. 1/0 is only needed if there are no service conductors- Note 2 of T. 250.66

I also run the #2 to the meter otherwise you need to get a gec to both panels.
Click to expand...

You would need #1/0 if your SE conductors were 500 Kcmil cu.
 
The water pipe connection to the subpanel would be OK if it was just being bonded. You're correct that if the pipe is part of the ground electrode system, you can't run your GEC from the subpanel.

If you do an overhead 400A service, what size wire do you run up the mast? I ran 400 KCMil which requires a 1/0 GEC. After the meter, I split to two sets 3/0 conductors.
 
Glad I saw this illustration. I have a similar situation & that covered my questions to a T.

Thanks!!
 
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