Grounding 2 - 100A Services

[Willy18]

Hi,
I am adding a 2nd 100A service to an old house for the attached apartment (no firewall). The existing 100A service is grounded to the house water main with no ground rods. I am adding another 100A meter pan next to the existing meter pan. The panels are in seperate locations.

Do I run my new service ground to the water main and then to the 2 ground rods?

Do I have to connect to the water main first?

Does the ground conductor have to be continous from the panel all the way to the ground rods, or can I use 2 water pipe clamps and go from the panel to the water main and then from the water main to the ground rods?

All advice appreciated!

 

[bphgravity]

Are you going to be in compliance with Section 230.2 of the NEC, and where did you say the service disconnecting means are going to be located?

All your other questions are answer in section 250.64 of the NEC. Namely, part (F).

 

[Dennis Alwon]

Hi,
I am adding a 2nd 100A service to an old house for the attached apartment (no firewall). The existing 100A service is grounded to the house water main with no ground rods. I am adding another 100A meter pan next to the existing meter pan. The panels are in seperate locations.

Do I run my new service ground to the water main and then to the 2 ground rods?

Do I have to connect to the water main first?

Does the ground conductor have to be continous from the panel all the way to the ground rods, or can I use 2 water pipe clamps and go from the panel to the water main and then from the water main to the ground rods?

All advice appreciated!

As Bryan has stated your disconnecets need to be grouped. They cannot be in two different locations unless you have a main ahead of the two meters.

The bond to the water main does not have to be continuous to the ground rod. In many cases, ie a 200 amp service, the wire to the water main would be larger than the wire to the ground rods. Table 250.66 to bond the water pipes and art. 250.66(A) for the rod.

I usually install 2 separate conductors. One to the water main and the other to the ground rods.