Bonding a new panel

[subelect]

One of wineries added on a garage. The owner is going to heat the new addition and this put us over the limit for his existing 2 200 amp panels. Now, the service entrances are in the middle of his house, well over 5' (our local AHJ's limit for service conductors) inside the house.
After a lengthy discussion with the AHJ and our POCO, the decision was made to come out of the bottom of the new double-throw (when the POCO drops the new meter loop on a CT), IMC 6" below grade to the side of the cement patio wall, run 2" EMT on the surface of the cement wall, LB up into the side of the garage, run EMT on the garage floor (cover the EMT with 2" of concrete) and come up into a 200 amp disco. This disco would be within 1' of the existing 2 panels. All 3 panels would be within reach of each other.
We will then come out the top of the new disco, 2" EMT to the new garage QO panel (with a main breaker).

How do you bond the new disco? Does it have to be bonded to the existing panels? Or do I have to run a separate GEC to a driven ground rod? (new addition will use PEX to bathroom, no copper.)
Do you have a Code reference?
Thanks,
Rick

 

[raider1]

Welcome to the forum.

Take a look at 250.64(D)(1) (2) & (3) in the 2008 NEC.

Here is what those sections say:

(D) Service with Multiple Disconnecting Means Enclosures. Where a service consists of more than a single enclosure as permitted in 230.71(A), grounding electrode connections shall be made in accordance with (D)(1), (D)(2), or (D)(3).
(1) Grounding Electrode Conductor Taps. Where the service is installed as permitted by 230.40, Exception No. 2, a common grounding electrode conductor and grounding electrode conductor taps shall be installed. The common grounding electrode conductor shall be sized in accordance with 250.66, based on the sum of the circular mil area of the largest ungrounded service-entrance conductor(s). Where the service-entrance conductors connect directly to a service drop or service lateral, the common grounding electrode conductor shall be sized in accordance with Table 250.66, Note 1. A tap conductor shall extend to the inside of each service disconnecting means enclosure. The grounding electrode conductor taps shall be sized in accordance with 250.66 for the largest conductor serving the individual enclosure. The tap conductors shall be connected to the common grounding electrode conductor by exothermic welding or with connectors listed as grounding and bonding equipment in such a manner that the common grounding electrode conductor remains without a splice or joint.
(2) Individual Grounding Electrode Conductors. A grounding electrode conductor shall be connected between the grounded conductor in each service equipment disconnecting means enclosure and the grounding electrode system. Each grounding electrode conductor shall be sized in accordance with 250.66 based on the service-entrance conductor(s) supplying the individual service disconnecting means.
(3) Common Location. A grounding electrode conductor shall be connected to the grounded service conductor(s) in a wireway or other accessible enclosure on the supply side of the service disconnecting means. The connection shall be made with exothermic welding or a connector listed as grounding and bonding equipment. The grounding electrode conductor shall be sized in accordance with 250.66 based on the service-entrance conductor(s) at the common location where the connection is made.

Chris