This is not a code issue but I don't know who to ask. I am a small electrical contractor in Houston, TX. In my 46 years in the trade I haven't done much residential work, just for friends and family.

I recently built a second residence in an un-incorporated area in the Texas hill country between Austin and San Antonio. There is no inspection of any kind. I had a builder build the house but did my own electrical. The builder and all the subconractors did an excellent job. I drove a ground rod on my 225 amp service and bonded to the cold water pipe. The water pipe is PVC up to the house then copper in the fill under the slab. The hot water pipes are copper and run in the slab also except on the second floor. I was even planning to bond the cold water to the hot water at the electric hot water heater. A friend of mine up there got shocked in the shower when the hot water heater element went out.

In that area of Texas builders use a real fine crushed limestone for fill since there is no bank sand available. The builder jumped on me for bonding to the cold water pipe, that it caused electrolysis. I asked the plumber his opinion and he said he thought it did too.

I told them I thought a water pipe ran in this semi-moist (maybe) limestone fill would not be able to make up its mind whether it was at ground potential or not and if I bonded it to ground I thought there would be less chance of elctrolysis than if I didn't. They are not convinced but I am still bonded to the cold water pipe.

I don't know of any experts on this subject. Can you either advise or recommend someone to talk to?

Tom Fitch

Tom- this is a code issue and I don't know if you are able to have access to a National Electric Code book or not but if you go to the local library and look in the 2002 edition of the National Electric Code Book published by the National Fire Protection Association and look on page 104 and page 110 there is considerable information that would have us grounding to the water piping system and including all piping systems, on the premise. As for electrolysis, you will have that whether or not you hook your ground wire up to the piping since electrolysis is a DC phenomenon. You might improve the situation if you ground it The well drillers quite often use that as an excuse for not allowing the electrician to ground the submerged water pump. A myth at best.

[This message has been edited by George Little (edited 12-01-2004).]