Grounding Bonding confusion

[commonslob]

hello hello
Been working on some condos and have just started tying in some services. I'm finding myself slightly confused with the ground system. The main service on three of the buildings is 400 amp 500 mcm conductors, the buildings have a water main, sprinkler main and #4 AWG connected to the footing. I was given a roll of #4 to run to the water and sprinkler mains and use as the main bonding jumpers. After looking in the book to refresh my memory I'm thinking this is no good. Now I'm not the foreman of this job but would like to know if my thinking is right so I can point it out if things need corrcting. There's a breakneck pace and a failed inspection could mess up the schedule. This is what I've come up with, please correct me if i'm wrong and point me in the right direction

My main bonding jumper needs to be 1/0
I need to run a 1/0 from the main panel to the water main
the bond to the sprinkler main should be 1/0? (thinking 250.104 A(1))
I can connect the #4 from the footing to the ground bar on the main panel (in one building the #4 will not reach, connecting it to the 1/0 as it passes by on the way to the water pipe is acceptable, right?)

Also the main panel also feeds panels in a second building. I need to bond the water and sprinkler pipes in that building too right? Would running a bond wire sized to the equipment ground of the largest panel in the second building to the ground bar of that panel be the correct way to do this?

Thanks much for your help, sorry if these are basic questions, but I'm used to simple house services where the main bonding jumper is just a screw and there are no sprinklers

 

[augie47]

all sounds good, other than in your seperate building, your grounding electrode conductor would be sized based on your feeder conductor, I believe..
(250.32{A})

 

[tryinghard]

...My main bonding jumper needs to be 1/0

Yep, 250.28, but often this is factory hardware

I need to run a 1/0 from the main panel to the water main

The water may or may not be an electrode, to be an electrode it will need to meet ALL the criteria of 250.52(A)(1). Refer to your engineered drawings to verify this.

If it is it will need to be supplemented with an additional electrode as per 250.53(D), bonded with at least #6 cu to the supplemental as per 250.53(E). The grounding electrode conductor (GEC) to the water pipe will need to be sized from Table 250.66 (1/0), an it must be installed unbroken as per 250.64.

If the water is not an electrode it will need to be bonded as per 250.104(A)

the bond to the sprinkler main should be 1/0? (thinking 250.104 A(1))

I believe it will be as per 250.104(B) "Other Metal Piping"

I can connect the #4 from the footing to the ground bar on the main panel (in one building the #4 will not reach, connecting it to the 1/0 as it passes by on the way to the water pipe is acceptable, right?)

The #4 if connected to rebar steel in the footing is your grounding electrode conductor (GEC), it must run unbroken to the service disconnect, again as per 250.64. You can tap but as per 250.64(D)

Also the main panel also feeds panels in a second building. I need to bond the water and sprinkler pipes in that building too right? Would running a bond wire sized to the equipment ground of the largest panel in the second building to the ground bar of that panel be the correct way to do this?

Every separate building will need an electrode as per 250.32, and these all need to connect to each other to form an electrode system. The feeder to each building will include an equipment-grounding conductor (EGC) and these electrodes will connect to this 250.32(B)(1). The water bonding in each building will also connect to the EGC and these are sized as per the feeder size but are not required to be larger than the feeder.

 

[infinity]

I can connect the #4 from the footing to the ground bar on the main panel (in one building the #4 will not reach, connecting it to the 1/0 as it passes by on the way to the water pipe is acceptable, right?)

Yes, all of the grounding electrodes may be connected together. The GEC to the water pipe will need to unbroken but the #4 to the CEE can be tapped to the GEC with a split bolt if you prefer.

 

[stickboy1375]

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