grounding to water pipe, copper to steel

gwaldDecember 1, 2012

I noticed that exiting my house (1965) is copper water pipe (the whole house is copper pipe). There is a copper ground wire connected to the copper pipe at that point (also coming from the house, bonding?). Then, the copper pipe goes into galvanized steel pipe (via a union) to the city meter.

I don't see a dialectric there between the copper and steel.

My questions:

1. Shouldn't there be a dialectric between copper/steel to protect the pipes from corrosion?

2. If there is a dialectric (if I add one), should I connect a copper wire between the copper and steel pipe for grounding purposes?

This all got started because the incoming water pressure is 80+ lbs and I want to add a pressure regulator.

Thanks for any help that you can offer.

rob

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Ron Natalie

The dielectric union might be a good idea. If you install one, yes then then you must bond the house water piping as well as the incoming service. Make sure you use the appropriate bonding clamps for the type of pipe you're connecting to.

    Bookmark   December 1, 2012 at 4:51PM
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brickeyee

" If there is a dialectric (if I add one), should I connect a copper wire between the copper and steel pipe for grounding purposes? "

There is not much point of a dielectric joint since the bonding connection simply defeats it.

    Bookmark   December 2, 2012 at 10:25AM
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Ron Natalie

There is not much point of a dielectric joint since the bonding connection simply defeats it.

No it DOES NOT. The problem the union is attacking is not the fact that there is an electrical connection there but the fact that two dissimilar metals are in contact with each other.

It is ABSOLUTELY required that those elements required to be grounded / bonded ARE. This would include incoming metal water pipes as well as the rest of the metallic water piping in the house. A jumper across the union might accomplish this (provided that the other connections are made) or you could make the required connections elsewhere.

The key with joining the bonding conductor to the pipe (ANY PIPE) is to make sure the clamp is listed for the type of pipe you are connecting it to.

    Bookmark   December 3, 2012 at 8:22AM
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brickeyee

"No it DOES NOT. The problem the union is attacking is not the fact that there is an electrical connection there but the fact that two dissimilar metals are in contact with each other. "

As long as the two metals are electrically connected the induced current will continue to flow and galvanic corrosion occurs.
Just like it works in every battery ever invented.

    Bookmark   December 3, 2012 at 9:03AM
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kalining

If the system is wired properly and no shorts, (if there is a short the breaker will pop) no voltage will flow threw
the ground wire so who cares.

    Bookmark   December 3, 2012 at 8:48PM
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brickeyee

'If the system is wired properly and no shorts, (if there is a short the breaker will pop) no voltage will flow threw
the ground wire so who cares. "

The couple made between the copper and steel will generate a very small voltage that creates a current that feeds the galvanic corrosion.

You have made a small battery cell.

Two different metals, an electrolyte, and (in this case) a short circuit (the bonding wire).

It has nothing to do with AC power flowing in the materials.

One of the methods used to protect large steel structures in contact with water is to put sacrificial anodes with a very small bias voltage to force the anode to pate onto the steel.

If the battery stops supplying voltage, you can measure a voltage between the sacrificial anode and the steel.

A dielectric fitting works by interrupting the contact and increasing the resistance of the electrical path (usually by breaking it).

    Bookmark   December 4, 2012 at 11:42AM
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kalining

funny how different our codes are. " connecting a ground wire or the bonding to a gas pipe is not permitted ". This is our gas code.

    Bookmark   December 4, 2012 at 12:20PM
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Ron Natalie

Who is talking about gas pipes?

What cell are you talking about BRICK? THere's a dielectric in the way in the proposed system. Providing an alternate current path (i.e. bonding) dioesn't change that. There may be corrosion somewhere, but it's not happening at the point of the copper-dielectric-steel connection.

    Bookmark   December 4, 2012 at 3:31PM
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kalining

i'm talking about plain ordinary pipe. Makes no difference
what the pipe carries.

    Bookmark   December 4, 2012 at 7:32PM
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kalining

It was just off topic. I've noticed in some of your codes
that the gas pipe can be used as a ground. It's not permitted up here. Difference in codes. That is all.

    Bookmark   December 4, 2012 at 7:48PM
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brickeyee

A steel pipe, a copper pipe, both with common electrolyte (water full of plenty of ions of various types).

The dielectric union slows corrosion at the point of contact, but a bonding wire across the dielectric re-establishes the electrical path for continued galvanic corrosion between the two metals.
It has been an issue for years that appears to have no practical solution.

And since slow corrosion is less of a safety hazard than inadequate bonding, bonding wins.

This post was edited by brickeyee on Wed, Dec 5, 12 at 9:13

    Bookmark   December 4, 2012 at 8:27PM
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rajendrafittings

for connecting copper and steel pipes u can use pipe fittings like elbow...for more information about pipe fittings check http://www.rajendrafittings.com

    Bookmark   August 25, 2014 at 5:33AM
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Ron Natalie

It's not pointless. The dieletric union removes the corrosion potential at that part. The bonding has the advantage is that the clamp for bonding is usually somewhere dry where there is not the electrolyte needed to cause the corrosion. Second, it's easily inspected and replaced if such corrosion occurs.

    Bookmark   August 25, 2014 at 10:06AM
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saltidawg

"It was just off topic. I've noticed in some of your codes
that the gas pipe can be used as a ground. It's not permitted up here. Difference in codes. That is all"

are you confusing bonding of the gas line which is REQUIRED?

    Bookmark   August 25, 2014 at 1:14PM
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joefixit2

This thread is nearly 2 years old and was brought back to the top by a spammer

    Bookmark   August 25, 2014 at 8:34PM
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saltidawg

And it continued on after the spammer... are you a Forum Monitor or Police?

    Bookmark   August 25, 2014 at 9:18PM
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joefixit2

Neither, just trying to be helpful, which is what this forum is supposed to be all about. What is your problem?

This post was edited by joefixit2 on Mon, Aug 25, 14 at 21:38

    Bookmark   August 25, 2014 at 9:36PM
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saltidawg

I assume you're funnin' us.

I was simply replying after TWO recent (today) posts.

I'll report this and no longer post.

Good by.

    Bookmark   August 25, 2014 at 10:10PM
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