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Old house, weird grounding wire attached to copper plumbing

Old house, weird grounding wire attached to copper plumbing

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  #1  
Old 01-12-16, 12:19 PM
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Old house, weird grounding wire attached to copper plumbing

You know those old houses where you find weird stuff and you wonder why? Well, I have one of those. This house is maybe built in the 1940s, maybe even earlier than that.

I noticed a peculiar thing the other day when looking at the copper plumbing underneath the house. There is a ground wire attached to one of the pipes that runs all the way to the electric panel on the outside of the house. I wonder why. New houses don't have such a grounding wire attached to plumbing... or do they?
 
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  #2  
Old 01-12-16, 12:28 PM
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There should be a grounding wire from the ground/neutral bus of the main electrical panel to the water service entrance if it is installed with metal pipe. This ground wire should also jump over the meter or similar break in the metallic piping (filter, etc). Generally this wire should be connected close to where the water service enters the house.

This does not apply to new houses that have plastic water entrance pipe. If they still have copper, it should be grounded to the main panel.
 
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Old 01-13-16, 08:29 AM
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Years ago the nearest cold water pipe was considered the best ground. Of course, this was back when all water piping was metal.
 
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Old 01-13-16, 02:19 PM
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What if I cut and remove the ground wire connected to the copper plumbing line? Its sortof in the way of my and I'd like to remove it and continue working on updating a few things underneath my bathroom area.

I assume that maybe back in the old days that having a ground wire connected to the copper water line was necessary due to the lack of a ground wire in the electrical cabling itself. However, my house has had its entire electrical system (panel and wires) updated within the last few years. And the electrical cabling already has a ground wire within the yellow electrical sheathing. Plus, there is a ground wire going from the electrical panel directly to the ground.

So, even though I don't have a plastic water pipe, I do have updated, current code-compliant electrical panel and wiring. Do I even need to have this old electrical ground wire connected to the copper water line when new homes don't even have one???
 
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Old 01-13-16, 03:05 PM
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I assume that maybe back in the old days that having a ground wire connected to the copper water line was necessary due to the lack of a ground wire in the electrical cabling itself.
Apples and oranges. The ground wire in the cables is the EGC (Equipment Ground Conductor). Its purpose is to provide a low resistance path to clear shorts to the metal of equipment housing. The wire to your copper pipe is the GEC (Ground Electrode Conductor) used to dissipate atmospheric charges and for bonding.
Do I even need to have this old electrical ground wire connected to the copper water line when new homes don't even have one???
The wire to the copper pipe is also for bonding so that there is less likelihood of there being a voltage difference between the grounded metal housing of equipment and the plumbing. Without it you could get a shock touching a refrigerator and a metal faucet at the same time.
Plus, there is a ground wire going from the electrical panel directly to the ground.
Depending on earth resistance two ground rods six feet apart may be required. Usually two rods are just used with out testing due to the complexity of the test. Your copper water pipe supplies the second ground. Both because of bonding and probable need for a second GEC it should remain.
 
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Old 01-13-16, 03:08 PM
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New homes are supposed to have the copper wire (#4 copper for 200 amp service) running from the panel neutral bus bar to the water pipe if that is metal exiting the house underground.

Your wire in question might not qualify as an electrical system grounding electrode conductor since the latter is supposed to be attached to the pipe before the meter and within 5 feet of where the pipe exits the basement. But it may qualify as a bonding jumper to ground the plumbing with in which case it can be attached to any point along the plumbing.
 
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Old 01-13-16, 06:29 PM
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There is a ground wire attached to one of the pipes that runs all the way to the electric panel on the outside of the house.
Are you sure this ground is still connected and not abandoned? When your entire electrical system was updated the contractor should have installed two grounds, one to the ground rod/rods and one to the water service within 5 feet of where it enters the house. If this is the only water service ground, you could replace it with a proper water service ground and then remove this old one.
 
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Old 01-15-16, 07:57 AM
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I just looked again at the ground wiring. I am sure that there is one ground wire going from the electrical panel directly to the ground and into the dirt under the electrical panel. There is another... A and this is the weird one... there is another ground wire going from the electrical panel to a incoming copper water line. That grounding wire is about maybe 10-15 feet in length, and the point where it attaches to the incoming copper water line is pretty far (maybe 25-30 ft) from the front of the house where the main water line enters the house.

Also, and this is probably of no consequence, but the drain pipes are all plastic PVC, but the incoming water line is copper.
 
  #9  
Old 01-15-16, 08:35 AM
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The existing ground wire, if connected to the water pipe after the water meter, will properly tie the cold water plumbing to the electrical system ground but you will need to run another ground wire from the panel to the water pipe before the meter and within 5 of where the pipe exits the foundation at the front of the house.
 
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Old 01-15-16, 12:04 PM
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It sounds like the ground wiring is correct, if anything above average, for a house of that age. I assume the electrical service has probably been redone at least once. As Allan suggests, you could bring it up to modern standard, but nothing you describe sounds dangerous or wrong. Does that ground wire that goes under the dirt re-emerge near the water meter and clamp to the water pipe? I've seen some that got buried in the crawl over the years, or even some that run under the basement slab.
 
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