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Gentoo · Oct 3, 2007, 08:29 PM

First off thanks everyone for all your help so far.

I have a question about a grounding rod. Can it be used in place of a water utility connection? My water meter is a good 50 feet away from my house and I am pretty sure that the pipes that run into the house are non-metallic, plus I have no clue where they run!

KISS · Oct 3, 2007, 08:56 PM

In new construction, I believe it's required. They will also try to bond the telephone and cable to the same zero volt reference. Lightning protection, if installed, should use a different rod.

Water meters have plastic end pieces now and old construction required a bonding jumper across the meter. I doubt that the pipe entering the premises from the utility is non-metal.

Sometimes, plumbing can run under the basement floor to get from one part of the house to the other.

tkrussell · Oct 4, 2007, 04:33 AM

If the home has a metal water pipe entering the building, that is 10 foot or more in length buried in earth, it shall be the primary grounding electrode. This then needs a supplemental driven ground rod, or other approved electrode, and connected together with the continuous grounding electrode conductor.

If the water line is used, any water meter needs to be jumped out, or grounded on both sides of the meter, as Kiss mentions.

If the water line is plastic, or inaccessible, then a driven ground rod is acceptable. Resistance of grounding electrodes must not exceed 25 ohms, so additional ground rods may be needed, again connected together with the continuous grounding conductor. In some areas, two ground rods are mandatory, so check with local codes.

While lightning protection systems need their own ground rod(s), those ground rods must be bonded to the electrical system grounding.

Gentoo · Oct 7, 2007, 05:39 AM

Thanks again for the great answer.

You mentioned the resistance must be less than 25 ohms. How can I check that? I have a digital multimeter, but I must confess I am still learning how to use it :o

tkrussell · Oct 7, 2007, 07:36 AM

Measuring ground resistance requires special equipment, a standard DMM will not do the job. Most inspectors either require to see the results of testing if the installer insists on one rod, or just require one additional rod. Most already know what to expect in their area.

Just add another rod at least six feet away from the other and you should be good.