Need help sizing bonding wire for 400A service

[buzzbar]

Hi,
I'm installing a new 400A 120/208V service. The service has. CT can with (2) 200A panels mounted back-to-back from the CT can.

My question is how to properly bond the hot and cold water pipes. Should I run a #2cu from EACH panel to the water pipes? Or is it okay to run a #4cu from each panel? I'm thinking that the bonding wire will need to be sized for the service size, not the 200A size.

All help is appreciated. Thanks!

Andrew

 

[infinity]

GEC's are based on the size of the conductor. What size conductors are you using?

 

[Cow]

Like Infinity said, you have to know the conductor size, it's all based off Table 250.66. I usually use 500's so....

You could run a 1/0 to the water pipe and bond the CT can to that.

Or you could take that 1/0 below your panels and tap a #4 off of it to each can.

Or take a #4 from each panel to the water pipe.

 

[buzzbar]

I have a parallel run of 250 AL to the CT can, then one set of 250 AL to the first 200A panel (Panel A), and another set of 250 AL to the second 200A panel (Panel B).

I realize that I have to base it on Table 250-66. Since this a parallel run, I would use a 1/0 CU, correct? If that's true, should I run the 1/0 copper from the water pipes to the CT can? Or a 1/0 CU from the water pipes to Panel A, and ANOTHER 1/0 CU from the pipes to Panel B?

OR.....

Should I run a single 1/0 CU from the water pipes to the CT can?

OR.....

Should I run a #4 CU from the water pipes to Panel A, and a separate #4 CU from the water pipes to Panel B?

Thanks for the help. I've been told many different things for the same scenario.

 

[buzzbar]

Like Infinity said, you have to know the conductor size, it's all based off Table 250.66. I usually use 500's so....

You could run a 1/0 to the water pipe and bond the CT can to that.

Or you could take that 1/0 below your panels and tap a #4 off of it to each can.

Or take a #4 from each panel to the water pipe.

It looks like you answered my question Cow, I should have read it more closely!
Since the CT can is right next to the panels, I think I'll just run a 1/0 from the water pipes to that.

Thanks!

 

[infinity]

It looks like you answered my question Cow, I should have read it more closely!
Since the CT can is right next to the panels, I think I'll just run a 1/0 from the water pipes to that.

Thanks!

I would run the #1/0 and tap of with split bolts to each disconnect. Something like this from the NECH:

 

[tkb]

I would run the #1/0 and tap of with split bolts to each disconnect. Something like this from the NECH:

I would use a copper bar to connect all of these grounds and then it would be available for the other systems.