grounding and bonding at water meter

[MannyBurgos]

Hello all. I really need help with this one. I've been tasked with a somewhat of a different project for me. Owner has a 2 family dwelling unit. Both main panels are located in basement and inspector wants units#2 to be re-located to that unit since unit #2 has no access to basement. Meter sockets will stay in place but I do have to add a main disconnect next to Unit #1 panel to comply with grouping of disconnect rules. Here's where my trouble starts; inspector wants a ground rod at meter trim which is not a problem and also wants a GEC from main(s) to water meter. How can I accomplish an NEC compliant GEC connection from water meter to the service disconnects? Can I terminate lets say from units#1 panel grounded bus bar to units#2 panel grounded bus bar and then back to water meter? I should also note that both panels will be bonded with emt if that makes a difference. I just did it last week at another property and the inspector approved the job but I want to be sure I am indeed grounding this equipment properly. I have my doubts on some of my local inspectors... Thanks all

 

[ActionDave]

I am having a hard time following what you are describing. Take a look at 250.64. Hope this helps.

 

[augie47]

The bottom line is Dave's reference to 250.64, (D) in particular.
Note you must either make the attachment at a common service point ahaead of your service disconnects (meter is often used if allowed), run one GEC to the water and tap to each disconnect or run an individual GEC from each disconnect to the grounding electrode (water pipe).

 

[MannyBurgos]

I am having a hard time following what you are describing. Take a look at 250.64. Hope this helps.

Sorry i kind of figured that. Let me try to make it short and sweet. We have 2 main disconnects. Is it compliance to run the GEC from panel #1 grounded bus bar to panel #2 grounded bus bar and then terminate at the water meter? Essentially what im trying to see is if i can use the grounded bus bars as a splicing point; GEC (wire) starts at panel #1, runs to panel #2 and terminates on a bus bar there. Then, another GEC (wire) goes from another screw on panel #2 and finishes at water meter...

 

[augie47]

Not permissible.
250.64 requires the install to be such that complete removal of one disconnecting means will not interrupt the grounding electrode conductor path of the remaining disconnects,.
Mike has a good pictorial. I will try to locate it,.

 

[petersonra]

Sorry i kind of figured that. Let me try to make it short and sweet. We have 2 main disconnects. Is it compliance to run the GEC from panel #1 grounded bus bar to panel #2 grounded bus bar and then terminate at the water meter? Essentially what im trying to see is if i can use the grounded bus bars as a splicing point; GEC (wire) starts at panel #1, runs to panel #2 and terminates on a bus bar there. Then, another GEC (wire) goes from another screw on panel #2 and finishes at water meter...

I think the GEC has to be unspliced or an irreversible connection used. I don't think a connection at a neutral bar counts as either.

As a practical matter, the electrons won't care any.

There is a provision somewhere to use a common GEC, but it requires a pretty large conductor.

 

[Michael15956]

Not permissible.
250.64 requires the install to be such that complete removal of one disconnecting means will not interrupt the grounding electrode conductor path of the remaining disconnects,.
Mike has a good pictorial. I will try to locate it,.

Can't he just use a crimp to splice the EGC's together and leave pig tails for the grounding bars?

 

[augie47]

As pointed out in 250.64, he can have a properly sized common grounding electrode conductor from the grounding electrode to the service location and tap from that to each disconnect by means of a listed grounding means.
(one option)

 

[MannyBurgos]

Not permissible.
250.64 requires the install to be such that complete removal of one disconnecting means will not interrupt the grounding electrode conductor path of the remaining disconnects,.
Mike has a good pictorial. I will try to locate it,.

Thank you! You hit the nail right on the head. Thats exactly what i wanted to know. Had a gut feeling i was terminating incorrectly. This was a different type of setup since i usually run my gec from main disconnect before meters. In this case, mains were after meter therefore a little more complex for me since i had two disconnects to ground. My local inspector always requires ground rod at meter and supplementary GEC to water meter. Thanks again.