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Joined: Aug 2001
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Maybe plumbers should be educated to install a temporary bonding jumper when opening a water or gas line?

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As far as the gas pipe is concerned, in this area the gas utility has always installed a dielectric fitting on the street side of their meter. The code does not now permit the underground gas piping to be used as a grounding electrode so there should be no current flow on the outside gas piping. The interior gas piping is required to be bonded, but this also shouldn't create a flow of current. However in older systems, the underground gas pipe may have been used as a grounding electrode. This was permitted by the NEC up until the 93 code, but only with the permission of the gas utility. The local gas utility never permitted this.
Don(resqcapt19)


Don(resqcapt19)
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Al,
After more thought the current flow through the underground water pipe does not always present a serious problem for the plumber. When the water pipe is opened with current flow the grounded conductor current will revert to its intended path, the service grounded conductor. The only voltage that should be on the water pipe at that time would be equal to the voltage drop on the service grounded conductor. Of course, this all changes if either your grounded conductor or your neighbor's grounded conductor has a high resistance connection.
Don(resqcapt19)


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Paul,
I am aware of some plumbers who do exactly that, but why should one trade be permitted (required) to intentionally create a possible hazard for other trades.
Don(resqcapt19)


Don(resqcapt19)
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I have heard more than one story of local plumbers getting shocked or tingles when replacing kitchen faucets or doing other local plumbing work. Sometimes because of the location of other utility grounds (phone, cable) sometimes from the use of dielectric fittings in plumbing systems and combinations of other things. Proper bonding of water systems is vital. I personally saw a house with the neutral/tension wire snapped with 120 volt loads during construction. The only thing left was the ground to the water pipe on the old panel which was temped in from a new service panel.

There are hundreds of different possible arrangements of electrical hazards and water systems (and gas, duct, gutter, siding, anything conductive, etc.) and all trades should be made aware of recognizing possible hazards.

I saw a ground connection for a satellite system hooked up to the non metallic seal-tite feed for an air conditioner.

I'm not sure anything but the death penalty would limit poor installtions. Even then I'm wouldn't bet on it.

Be careful out there. Don't trust anyone else's installations.

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Be careful out there. Don't trust anyone else's installations.

You can say that again Steve!


Joe Tedesco, NEC Consultant
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resqcapt19
What remedy do you propose. If we do not use the underground metallic water piping as a grounding electrode we still have to bond the interior metal piping systems to the grounded conductor at the service. To eliminate the common neutral pathway over the public water systems dialetric unions or insulating pipe segments would have to be added to all the service laterals into homes. In the absence of underground water pipe electrodes many buildings would have no effective grounding electrode.

I suppose we could all buy heavy SDS hammer drills and ground rod cups with which we will drive sectional ten foot rods with spline couplers.
--
Tom


Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
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