Cold water pipe

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tkirk911

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We are wiring a senior center and some townhomes in Upper Darby, PA. Each building has a copper water pipe feeding into each building and is buried in excess of 50' to main piping which is pvc. The water company has told us not to bond to their cold water pipe. We bonded within 5' of entrance and then jumpered around meter. We were instructed to remove this. The reason given was that hair dryers convert a/c to d/c and this would leak back out on the cold water pipe and cause rapid deterioration of there piping. Has anyone ever heard of such a thing? P.S. Electrical Inspector stated that it will be bonded. Any help would be appreciated.

[ June 07, 2004, 08:31 PM: Message edited by: tkirk911 ]
 
Re: Cold water pipe

This electrical inspector would also require it to be bonded and used as a grounding electrode.

Ask the water guys what their feelings are about the pipe becoming energized.

[ June 07, 2004, 08:07 PM: Message edited by: ryan_618 ]
 
Re: Cold water pipe

If the metal pipe ends after 50' in plastic, very little neutral current will flow, so the small DC component produced by some devices will not be able to flow to any significant extent. Some people think the current flows in the water, but that is not true of drinking water. It would have to flow through the earth, but at neutral voltages that would be almost unmeasurable.

In fully metallic water systems there is a DC corrosion effect in some cases, but not when plastic stops the flow.

Karl
 
Re: Cold water pipe

Maybe the concern here is not so much the copper plumming, but the construct of the alloy (lead/non-lead) around the solder joints. Not sure how the interaction of a DC leakage would affect or accelerate deterioration of the copper/alloy mix. Or is it really more of a safety issue? Just a guess.
Would like to hear more about this!
 
Re: Cold water pipe

Ask the water guys what their feelings are about the pipe becoming energized.
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I think this is exactly the reason they do not want it used as a EGC.

With the street end of this pipe ending into plastic main and connecting the house end of the pipe on to the service neutral you have set the water guys up for a shock. :eek:

The water guys may have the right idea here.
 
Re: Cold water pipe

Bob: I would want it bonded to prevent it from becoming energized. Your concern is a valid one...Don and I had the same conversation over PM's.

I just think that the likeliness of the water piping knocking someone on their butt from nuetral current is slim. I also think it is more likely that the pipe could accidently become enrgized from an ungrounded conductor and therefore needs to be bonded to create an effective ground fault current path.

In all honesty, the chance of either one happening are pretty slim, IMO.
 
Re: Cold water pipe

Ryan my suggestion would be to bond the interior metal piping system, have a dielectric fitting at the water meter and leave the portion from the meter to the plastic main un-bonded.

Of course we would need some other grounding electrode but done this way it would be imposable for the water workers to be injured from electric currents on the pipe.

What is gained by bonding this 50' of pipe? :)


Bob
 
Re: Cold water pipe

I agree Bob, I think it would be safest to bond the interior piping to prevent it from accidental energization, and find a better way to earth the system, such a concrete encased electrode or other.
 
Re: Cold water pipe

I have recently had an experience with the 'Water Company' installers. The safety training they receive is suppose to 'enlighten' them as to the dangers of current on 'their' piping. My experience has shown me they are not properly trained - shame on their instructors :mad: .

I say that the DC current of the hair dryers is bunk and bond those cold water installations pronto, as it is OUR code. If the Water Co. wants them removed, give that to me in writing!!!

As to current on their pipes being dangerous, I say that all work has inherent dangers, and that is why proper training helps to alleviate some of those dangers. Walking across the street has dangers too, just look at all the people killed in this country by crossing the street :eek: .
Pierre
 
Re: Cold water pipe

Pierre here is the installation.

From th OP
Each building has a copper water pipe feeding into each building and is buried in excess of 50' to main piping which is pvc.
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How will bonding this underground potion of copper pipe going to increase safety to anyone? :(

I agree it is in our code, perhaps this should change.

Bob
 
Re: Cold water pipe

What would happen if you a lightning strike come in on the line you would have a large potential between water and neutral.I think it should be bonded.
 
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