Changing grounding sytem or not?

[Charles M]

The water service is replace from the street into the building. The existing water service will be disconnected and will stay in place. The Engineers planning the retrofit says the building grounding system will stay as is [bonded to the existing/discontinued water pipe]. Toughts?

One electrician expresses the grounding is no good without water in the line... thoughts?

 

[Buck Parrish]

As long as ten ft. or more is in contact with the earth. We are required to use it any way. Even if it is no longer in use.

 

[nunu161]

I think its ok as long as its over 10 ft. long. going by 250.52(A)(1) and 250.52 (A)(7) if you dont consider it a water pipe anymore

 

[augie47]

Instead of being a 250.94(A) Bond, it becomes a 250.94(B) bond.

 

[macmikeman]

Maintain a minimum of ten feet in direct contact with the soil, cap the low end of it off, and fill it with water. Presto, a 250.52 gec is present. Stagnent water might be prohibited by some other code someplace, but it doesn't turn up in ours.

 

[tryinghard]

Instead of being a 250.94(A) Bond, it becomes a 250.94(B) bond.

augie47 do you mean 250.104 (2008)?

Keep in mind if the water pipe is a compliant electrode it includes a supplemental electrode, 250.53(D)(2) if so this would become the electrode. But I would check this anyway, water pipes are volatile this way.

 

[augie47]

augie47 do you mean 250.104 (2008)?

Keep in mind if the water pipe is a compliant electrode it includes a supplemental electrode, 250.53(D)(2) if so this would become the electrode. But I would check this anyway, water pipes are volatile this way.

I did (not sure how my mimnd does that),,,
If it's a metallic water pipe that is an electrode then 250.104(A) applies, if it is a metal piping system but not an electrode, it still is required to be bonded, so 250.104(B) would be applicable.
As you say, beyond that I woiuld verify the presense of the supplemental electrode keeping in mind there must be at least one electrode listed in 250.52.

 

[Charles M]

Thanks for the help.

Does the pipe have to hold water to be considered supplemental? I guess it wouldn't be a water line with no water in it...:grin:

 

[hillbilly1]

No, as the pipe itself is the electrode.

 

[augie47]

You need to keep in mind that bonding of metal piping systems (other than ones used as electrodes) is to keep them from having a potential to ground. Although 250.104(B) describes "piping likely to be energized, even if the pipe was abandoned as a water system and it still ran through the building it doesn't hurt for it to be bonded. For example, if it became energized and you were crawling abound in a crawl space the "hot" pipe is a potential hazard. You will note in 250.104(B) the FPN even suggests bonding duct work. I have seen fatalities where construction personnel have come in contact with "hot" ducting and piping,