ECN Forum Forums Code Related Discussion NEC & other Code issues Ground rod & water main

Hi... Just wanted some feed back on installing 2 ground rods for a residential service instead of 1 ground rod and the water main. Speaking with a inspector here in Rochester NY , he said they would prefer to see 2 ground rods. That was new to me.. anybody have a opinion on this subject... thanks ToHo

Please read 250.50. It requires the water piping system to be used as a grounding electrode (assuming it is in contact with the earth for 10 ft or more) and another grounding electrode. If the additional grounding electrode is a driven electrode, a maximum of 25 ohms must be met or a second one must be driven no closer than 6 ft to the first one.

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Charlie Eldridge, Indianapolis, Utility Power Guy

Thanks charlie... I agree 100%. Its always nice to get another view. If a well is used on the premise w/ pvc piping into the house. Would you use 2 ground rods or could you use only one if the ohms reading was acceptable?

You would be compliant with only one rod as long as the resistance is less than 25 ohms. Also, even though the waterpipe from the well is PVC, if the water system in the house is metallic, then it must still be bonded to the service. Not as an electrode, but to make it the same potential as the equipment grounds.

Gary, I agree completely.