# Bonding water pipe in a home



## SWDweller (Dec 9, 2020)

Table 250.66
conductor is required to be a *minimum size of 8 AWG copper and need not be larger than 3/0 AWG copper*

Guessing at the conductor size feeding your panel #2 copper conductor


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## LGLS (Nov 10, 2007)

Bond the well CASING.


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## Almost Retired (Sep 14, 2021)

SWDweller said:


> Table 250.66
> conductor is required to be a *minimum size of 8 AWG copper and need not be larger than 3/0 AWG copper*
> 
> Guessing at the conductor size feeding your panel #2 copper conductor


why would you guess that when he said a 200A service?


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## Dennis Alwon (May 9, 2009)

You would need a #4 copper however if these are small section of piping there is no need to bond it.


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## splatz (May 23, 2015)

If it's a grounding electrode, then it has to be bonded to the GES following all the rules. So if it was the incoming water service or a pipe that runs underground, it would be a grounding electrode, and all those rules apply including Table 250.66. 

But if it is not, and you're just considering that pipe metal that's likely to become energized, does 250.66 apply? I see the OP's point, I don't think it would. If not, then what rule if any tells you what size the wire must be?


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## Almost Retired (Sep 14, 2021)

splatz said:


> If it's a grounding electrode, then it has to be bonded to the GES following all the rules. So if it was the incoming water service or a pipe that runs underground, it would be a grounding electrode, and all those rules apply including Table 250.66.
> 
> But if it is not, and you're just considering that pipe metal that's likely to become energized, does 250.66 apply? I see the OP's point, I don't think it would. If not, then what rule if any tells you what size the wire must be?


i would think you would need to consider the possible fault current, before deciding on a smaller wire size
if it is a location/situation where it is way down stream of the service, then yes possible fault current will probably be low
on the other hand, the water inside the nonmetallic piping is going out in the earth and at some point will encounter a metallic valve in the earth
at this point it might be considered as part of the GES

from what we know, it seems to be one of those scenarios that does not necessarily fall under precise code rules
if i were there ... i would err on the side of caution without too much head scratching over it


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## Buck Parrish Electric (Jan 8, 2021)

steve517 said:


> I have a question about bonding grounding water pipe in a home.
> There is pvc piping coming into home from a well. In the addition there is going to be all Pex from water service. The existing pat of the home has copper metal piping. What is the requirement on bonding the copper metal pipe. What size conductor would be needed back to the electrical service? 200 amp service with ground rods for electrodes. I'm thinking #6 as it in not a part of the electrode system.


Your electrician should be familiar with NEC 250.104


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