I am wiring a residential building with 4 units. Each of the units will have their own water supply and meter. I have installed the typical 5 gang meter pack (4 plus public)with service disconnects directly next to the meters.
For grounding I have ran a continuous number 2 copper conductor the length of the building and split bolt connected short lengths down to each water line to bond all back to the main service equipment ground lug. I have also driven a supplemental ground rod at the meter enclosure and ran number 4 to the rod as a supplemantal ground.
The Inspector loved it but I would like your opinion.
If you ran the gec continuous to one electrode then tapped off using split bolts to each unit water service you are not splicing the electrode. The taps are really bonding jumpers to each addtional water service. You should have two supplemental rods unless you have 25 ohms or less on one. You only need # 6 to the rods.
Re: Grounding electrode conductor#86599 11/15/0307:21 AM11/15/0307:21 AM
From what I gathered from the info provided, the water pipes in each unit are bonded, they are not ground electrodes. I am assuming that the underground portion of the water services is plastic, if not the following does not apply. The code requires a continuous conductor to the main ground electrode, in this case the ground rods. The H2O bond wire is allowed to be tapped/spliced as long as it is sized to the service entrance conductors, not the breaker size. I don't know what size SE conductors were run, but fromwhat I see this is a code compliant installation. Now after rereading the original post, if the water underground services are indeed metalic... you would have to go to the main ground electrode unspliced. Could any ONE of the water services be the main ground electrode and the other 3 be supplental? I think that is how I would look at it in my town. If this is the case as long as you go to any one of the water services unspliced (even the last one) you could splice to the other 3.
Re: Grounding electrode conductor#86602 11/16/0306:17 AM11/16/0306:17 AM
If the main water services are plastic entering the building i think you can run your bond back to each sub-panel in each unit or you can splice the bonds and run back to service equipment or to ground rod or rods. Any thoughts on this would be a help to understanding this.
Re: Grounding electrode conductor#86604 11/16/0308:40 AM11/16/0308:40 AM
The 3 water services are all copper throughout. I do in fact have a continuous connection from the furthest water service back to the main GEC lug. The remaining two water services I have simply exposed some of the copper on the continuous GEC and split bolted them that way. Sort of like a continuous ground bus running the length of the building. On one end I have the conductor landed on the main GEC lug and the other is on the furthest water line....continuous with no breaks in the conductor. I hope this makes sense.