Grounding via copper water pipe

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Old 01-17-15, 07:24 AM
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Grounding via copper water pipe

I have a specific question about running a ground wire using Copper pipes.
I noticed that the electrician would always install a jump at the water heater, in addition to the ground wire being connected at the very end past the water meter.
I wonder....why do this? I haven't seen any electrical wires grounding to any of my plumbing fixtures or pipes.
It seems there is really only need for that single ground wire connecting to the water pipe as it enters my house.

thanks!
 
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Old 01-17-15, 08:47 AM
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Jumpers around water meters and water heaters insure positive bonding even if the device is removed during service.
 
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Old 01-17-15, 10:07 AM
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in addition to the ground wire being connected at the very end past the water meter.
The continuous ground wire should be clamped after the meter in addition to ahead of the meter. Like Telecom Guy said.........

telecom guy
Jumpers around water meters and water heaters insure positive bonding even if the device is removed during service.
 
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Old 01-17-15, 10:09 AM
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I understand that....my question is more about WHY ground above from the water meter and up the piping ? Why isn't it enough to have the main ground wire connect to the water pipe at the very base closest to the ground ?

Is there any electrical ground running down the pipes from within the rooms (bath/kitchen etc...) ?
 
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Old 01-17-15, 10:13 AM
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All pipes and faucets need to be bonded. The jumpers are there to insure if a water heater or meter is removed the bond isn't broken.
 
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Old 01-17-15, 10:17 AM
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You have to bond around the meter for the same reason you bond around the other appliances. If the water meter is removed for service you will not loose the grounding path.

Once the metal piping is grounded, it is grounded through out the house. Jumpers are added anyplace the water pipes continuity could be broken. So, if somebody decided to add a house water filter, a jumper should be added around the filter as it would break the continuity of the metal pipes.
 
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Old 01-17-15, 10:23 AM
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I understand that....my question is more about WHY ground above from the water meter and up the piping ? Why isn't it enough to have the main ground wire connect to the water pipe at the very base closest to the ground ?
This prevents such things as shocks in the shower. You want all indoor metallic plumbing to be bonded at all times to the service entrance.
 
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Old 01-17-15, 11:43 AM
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telecom guy....so your last post is what I am looking for....but curious...how would one get shocked in a shower ? Where would the power come from travelling down the pipes from what source?

Please be patient with me...I am just trying to understand the logic behind using copper pipes for ground......
I guess maybe I should have started with the following:

My understanding of electrical systems is that the power comes from the grid into the main panel and there it flows through the wires. All outlets, fixtures, appliances are grounded via electrical wires and so the ground is established for the entire house via the electrical wiring and to the outside ground.

Where is the charge created that it needs to travel down the water pipes ?
How does it fit with the house electrical system ?
 
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Old 01-17-15, 11:51 AM
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It is not necessarily to prevent shocks in the shower, it is more in case a metallic pipe becomes energized by a loose wire, bad electric appliance, or some other mishap. By grounding the water system, if any of the above happen, the circuit breaker or fuse will blow and disconnect power to the circuit. If a pipe does become energized and it is not grounded, then the risk of shock is greatly increased. Back to the shock in the shower thing.
 
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Old 01-17-15, 12:57 PM
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Thanks Tolyn...that makes sense now.... how is that handled in case of houses with PEX tubing ?
I guess there is no concern about a hot wire touching PEX line as it is non-conductive but what about appliance like dishwasher....where would the build up charge escape then if there was a faulty ground ?
 
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Old 01-17-15, 01:55 PM
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... houses with PEX tubing ...

Using the jumpers around the water meter, water heater, and perhaps between two sections of metal pipe joined by a section of plastic pipe, the intent is bonding the plumbing to the electrical ground, not bonding the electrical system to use the plumbing as a ground (except for a section of metal cold water pipe from where it exits the house underground).

Even given the fact that if A is bonded to B then B is bonded to A.

The wire(s) across the water meter, etc. as described here are called bonding jumpers, not grounding electrode conductors.

The wire from the panel neutral bus to the water pipe where it exits the house is a grounding electrode conductor.

A dishwasher's (or other water using electrical appliance's) frame will be adequately bonded to the electrical ground via the ground wire (equipment grounding conductor) in its power cable or otherwise accompanying the current carrying conductors serving said dishwasher. The dishwasher plumbing, if it includes an all metal path including proper bonding jumpers from dishwasher frame to a point on the house grounding electrode system, will also properly bond the dishwasher frame to the electrical ground. Then, should a defect or malfunction or disintegration result in a live wire or object coming in contact with the dishwasher frame, any current (fault current) that might flow will go to the electrical system ground and, if that current is great enough (which with a typical fault it probably will be), trip the breaker for the dishwasher's circuit.

... where will the charge escape ...

Now if there is a faulty (here a defect in terms of non-continuity) ground -- neither a complete equipment grounding conductor path via electrical wiring to the panel nor a complete metal path to the electrical ground via plumbing -- then, as an independent event, should a fault (here a defect causing unwanted continuity) occur between a live object within and the (dishwasher) frame, no fault current will flow immediately (the built up charge on the frame at a potential of 120 volts relative to ground will not bother to escape). But if just the right circumstances are had when someone touches the dishwasher frame, a current may flow (the built up charge may then try to escape) through that person to some other grounded object and perhaps be large enough in milliamperes to electrocute him.
 

Last edited by AllanJ; 01-17-15 at 02:33 PM.
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Old 01-20-15, 08:04 AM
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Three additional reasons that haven't been mentioned.

Metal pipes need to be bonded to the same plane to reduce corrosion by electrolysis. Even very small difference in charges over a long period of time can ruin metal piping systems. Good bonding reduces that effect.

City water systems and/or metal well casings provide excellent grounding for lightning protection as they are highly conductive and can dissipate charge deep into the soil.

Back in the old days, and more recently in Canada, copper water pipes were considered a legal ground for the electrical system. In an older home it is possible (and should be assumed) that some ground wires might be connected to the water pipes hidden somewhere in the walls. Maintaining the jumpers around appliances and meters keeps that ground path intact just in case it's being used that way.
 
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