Water pipe ok for grounding electrode?

[epd807]

I recently installed a new 150A service panel into and old house, replacing the old service panel. I connected the neutral and ground busses to both the incoming copper water supply pipe (within 5 feet of its entrance to the basement and on the incoming side of the meter) and to an 8' x 5/8 ground rod and the bonded the busses to the panel. I didn't check the impedance to ground, so it may have been more than 25 ohms, but the Poco claimed that I needed 2 ground rods, more than 8' apart. They didn't cite the possibility of too high an impedance to ground, the problem was that the water supply pipe is no longer able to be used as a grounding electrode as per a change in the NEC in the last 12 months. I do my best to keep up with late breaking code changes...did I miss something??? HELP! Thank you.

 

[tom ogryski]

Re: Water pipe ok for grounding electrode?

No doubt about it, you need two ground rods at least 6 feet apart, per 250.56 Even if you did the test, it is unlikely that the resistance of one electrode would be less than the required 25 ohms.

The 8 foot spacing may be a power company requirement. The rods do work better if spaced more than the minimum distance.

Not using an underground metal water pipe as a grounding electrode? That would be a major change that every trade magazine would have announced.

[ December 02, 2003, 05:07 PM: Message edited by: tom ogryski ]

 

[bill addiss]

Re: Water pipe ok for grounding electrode?

the problem was that the water supply pipe is no longer able to be used as a grounding electrode as per a change in the NEC in the last 12 months

This sounds like a misunderstanding on someone's part. There was no change in the NEC.

Bill

 

[hurk27]

Re: Water pipe ok for grounding electrode?

Sounds like your in a area that don't have a AHJ (city inspector) and the POCO does all the inspecting but as far as the NEC goes there has been no changes in the requirment of bonding the water pipe Even if there is well water (unless all the pipes are PVC). but what the NEC does say is that if you dont reach the 25 ohms then you have to install another rod and your done. but what you could have is a POCO requirment that requires you to install two rods.

 

[pierre]

Re: Water pipe ok for grounding electrode?

EPD

There are as many 'stories' as there are people. Keep reading the NEC, that is the way to go.
BTW - the connection to the cold water pipe does not have to be to the street side first as per the NEC, just within 5 ft of the entrance. A lot of the POCOs do require street side first though, and some people confuse this requirement from the POCO as an NEC requirement.

Pierre

 

[epd807]

Re: Water pipe ok for grounding electrode?

Tom, Bill, Hurk, Pierre et al,

Thank you very much for your responses! I didnt think there had been any changes in the NEC but I had to ask, Im glad I didnt miss something...thanks again for the info!