I had always heard that a cold water pipe makes a good electrical ground. If copper, use a copper clamp and if steel use a steel clamp? Can copper react with steel? Seems I remember some nasty incompatabilities between certain metals from high school science. Can someone give me the basics or point me in the right direction regarding incompatible metals and corrosion? Thanks. LB
What are you grounding and why?
The ground from my original telephone service that was done in 1933. I'm getting rid of that cold water pipe soon and need to move it to a newer pipe a few feet away. I know the telco would probably come and do it for free, but I hate to give up a whole day of work waiting for them to show up.
That way of thinking should be avoided, plumbing should not be used for grounding electrical devices how ever, the plumbing should be grounded to a real earth ground in various places but not for the use to allow electrical devices to connect to the pipe as a path to an earth ground.
Problem 1. Most plumbing these days have plastic here and there and you can not rely on it being firmly in the ground along with soil problems.
Problem 2. Plumbing should have a good earth ground connected to it, this helps reduce the chance of shock if one should be hanging on a faucet in the middle of a T-storm or standing in the tub etc.. Also, electrical devices connected to the pipe if enter in a state of short can cause current to flow through fittings and end up causing electrical shock to others that have their hands on the plumbing else where.
In practice, the Electrical system should have it's own earth ground electrode entering the sub panel where it is to be connected..
If you are concerned about earth grounding on a device then drive an electrode into your ground and connect to that. also use appropriate ground wire., if you're in an R.F. environment and trying to reduce RF from riding up the ground wires? i have used a shielded ground made from heavy gauged coax. With that, you connect the braid and center together at the ground electrode, bring it into the location of the equipment and use only the center conductor, tape back the shield so that it does not come in contact with any thing on that end.
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Do Telco's ground these at the residence any more? Might be worth a phone call first.
Copper or steel pipe I used a brass grounding clamp and made sure the pipe was really clean (emery cloth) in either case.
What you wrote could be taken the wrong way. If an electrically continuous metal underground water pipe exists on the premises and is in contact with the earth for at least 10 feet, it is *required* to be part of the grounding electrode system per NEC 250.50.
I think your point is that the devices that use electricity should be connected to an equipment grounding conductor (EGC), not the cold water piping in your house. The EGC is connected to the electrode grounding system at the service panel. The electrode grounding system includes water pipes in accordance with the paragraph above.
And the way of thinking that says dissimilar metals in contact with one another is correct - you need to be sure that proper metals are chosen.
Ed
In ancient times, when we had party lines, with selective ringing arranged by connecting ringers between one or the other phone wire and ground, you did need a ground, but I don't think that system is used much any more. Unless you have such an arrangement, you shouldn't need a ground for the phone line.
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Cold water pipes used to make good grounds. With modern construction there may be plastic in the system. - inside or outside the house.
Galvanized pipe may have bad electrical joints so should be connected as close to the street (service entrance) as possible.
Don't use it for a power ground - Safer to put in a proper ground rod.
1/2" or 3/4" 10 foot copper pipe with a heavy gauge wire sweated to it works well. If the soil isn't too rocky the pipe can be washed into the ground. Or just get a copper- weld ground rod and drive it into the ground. They don't cost muchDissimilar metals should be avoided due to galvanic action and corrosion. You can usually find grounding clamps with either copper plating or zinc plating for the purpose.
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The ground on telephones these days is for the lightening arresters. It won't affect the operation of the phone but may save you or your modem from destruction.
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