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Grounding to plumbing


elgato
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What is the intent behind the rule that a jumper be placed from one side of the water meter to the other when the cold water line is used as a ground connection? Is it because the meter could be removed and the ground lost? or due to some issue with conductivity through the meter? or something else? Thanks.

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Originally posted by elgato

What is the intent behind the rule that a jumper be placed from one side of the water meter to the other when the cold water line is used as a ground connection? Is it because the meter could be removed and the ground lost? or due to some issue with conductivity through the meter? or something else? Thanks.

Probably both. You certainly don't want the grounding electrode to disappear when someone removes your meter. That could also be dangerous if any current happens to be flowing over the water pipe - the plumber could be electrocuted. Also, though I've never seen one, I suppose it's possible that there are non-couductive meters out there.

250.53(D)(1) Continuity. Continuity of the grounding path or the bonding connection to interior piping shall not rely on water meters or filtering devices and similar equipment.

- Jim Katen, Oregon

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Originally posted by elgato

I found this situation yesterday. There is no jumper, but the meter is installed on a separate leg.

From an electrical point of view, I think it's fine. If you were to remove the meter, you'd still have electrical continuity. If the meter were made of plastic, you'd still have continuity.

But I'm curious about how that water meter works. Does that funny L-shaped cross fitting scoop up all the incoming water and direct it through the meter?

- Jim Katen, Oregon

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Originally posted by InspectionConnection

We were taught that some meters may be installed with insulators at the connection points. I've never seen one myself...

There's no reason why someone couldn't use a dielectric union to connect a meter, though I'm not sure why they'd want to. Every meter I've seen is brass and galvanic corrosion wouldn't be a concern.

Perhaps they'd want to prevent the odd electrical current from interfering with the electronics in these newer meters?

- Jim Katen, Oregon

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