grounding receptacle to water pipe cause breaker to trip?

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haywire

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Milpitas, ca
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Electrician
I was asked by a neighbor if grounding 1 receptacle to a water pipe can cause the water heater breaker to trip, they are separate circuits and the house is not grounded for the most part. I will be looking at it today.
 

big john

Senior Member
Location
Portland, ME
Short answer: No. If installed properly, there's no reason the line conductors should ever share part of a circuit with equipment grounds. So modifying the equipment grounds should not change the amount of current flowing through the breaker.

Besides which, a receptacle cannot simply pick up a ground point from the nearest water pipe. Check out 250.130(C) for how to ground previously ungrounded receptacles.
 

GoldDigger

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Placerville, CA, USA
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Retired PV System Designer
Short answer: No. If installed properly, there's no reason the line conductors should ever share part of a circuit with equipment grounds. So modifying the equipment grounds should not change the amount of current flowing through the breaker.

Besides which, a receptacle cannot simply pick up a ground point from the nearest water pipe. Check out 250.130(C) for how to ground previously ungrounded receptacles.
It can cause a trip if there is an existing ground fault in the heater element and that fault could not trip the breaker because of a poor fault return path.
 

Little Bill

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Tennessee NEC:2017
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It can cause a trip if there is an existing ground fault in the heater element and that fault could not trip the breaker because of a poor fault return path.

If that water pipe created a ground for the added receptacle, there should already be a path for any fault on the water heater. That's assuming the pipe runs to (directly or indirectly) the water heater.

@ the OP:
Try taking the ground loose from the water pipe (carefully) and see if the breaker holds for the water heater.
Also, try disconnecting the wires to the water heater, connect the ground back to the pipe, then see if the breaker trips. If the water heater doesn't not have an EGC run to it, I would suggest one be ran to it. Probably just a 10-2 w/ground.
 
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GoldDigger

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If that water pipe created a ground for the added receptacle, there should already be a path for any fault on the water heater. That's assuming the pipe runs to (directly or indirectly) the water heater.

@ the OP:
Try taking the ground loose from the water pipe (carefully) and see if the breaker holds for the water heater.
Also, try disconnecting the wires to the water heater, connect the ground back to the pipe, then see if the breaker trips. If the water heater doesn't not have an EGC run to it, I would suggest one be ran to it. Probably just a 10-2 w/ground.
It is not uncommon to have a dielectric union or PEX plastic pipe at a hot water heater. Or even a relatively high resistance connection.
 

al hildenbrand

Senior Member
Location
Minnesota
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Electrical Contractor, Electrical Consultant, Electrical Engineer
@ the OP:
Try taking the ground loose from the water pipe (carefully) and see if the breaker holds for the water heater.
Good suggestion.

I agree with Golddigger, that a possible issue is that one of the energized conductors or heating element filaments is in contact with the metal of the body of the water heater, and that the water heater was floating, energized.

Test the body of the water heater for voltage, if the water heater branch circuit breaker holds when the "receptacle ground" is removed from the water pipe.
 

Dennis Alwon

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Chapel Hill, NC
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It sounds like you may not be a contractor and are working for a neighbor. You cannot just connect to a water pipe. If you install an equipment grounding conductor you can do a few things but essential it must connect directly to a grounding electrode or back to the panel.

We used to do this years ago but now we prefer going to the panel with a new circuit. We used to run the equipment grounding conductor to the metallic water pipe that comes into the building but this is not a good idea anymore on houses where the grounding electrode conductor is not connected back to within 5' of where the pipe comes into the building.

Often the water mains are replaced with non metallic pipe so it is best to either connect to the grounding electrode conductor or back to the panel.
 

Little Bill

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Tennessee NEC:2017
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It is not uncommon to have a dielectric union or PEX plastic pipe at a hot water heater. Or even a relatively high resistance connection.


Ok, if the pipe provides the ground (EGC) for the receptacle, that means that whatever else is connected to that pipe would be grounded. But if the water heater did have the the dielectric union or plastic, then the fault still could not find a path back to the panel.

So,
1) pipe provides path back to panel, fault in water heater would cause the breaker to trip if no if no dielectric union-plastic-high resistance. This would have happened whether the receptacle EGC was connected or not.

2) If the water heater has the dielectric union-plastic-high resistance connection, then no path for fault to get back to panel.



BTW, we only need "cold" water heaters here!:p
 
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Little Bill

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Tennessee NEC:2017
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Ok, if the pipe provides the ground (EGC) for the receptacle, that means that whatever else is connected to that pipe would be grounded. But if the water heater did have the the dielectric union or plastic, then the fault still could not find a path back to the panel.

So,
1) pipe provides path back to panel, fault in water heater would cause the breaker to trip if no if no dielectric union-plastic-high resistance. This would have happened whether the receptacle EGC was connected or not.

2) If the water heater has the dielectric union-plastic-high resistance connection, then no path for fault to get back to panel.



BTW, we only need "cold" water heaters here!:p


Bump & to see if OP (Haywire) had a chance to look at this problem.
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Ok, if the pipe provides the ground (EGC) for the receptacle, that means that whatever else is connected . . .
Little Bill, when I read the OP, I got the sequence just the opposite. The receptacle EGC was added from a formerly two-wire-ungrounded receptacle by running a wire to a water pipe ASSUMING the water pipe was a good ground. The OP reads to me saying that before this change, the water heater OCPD ran just fine. After adding the receptacle EGC wire caused the water heater breaker to trip.

That is to say, in my suspicion, the water pipe never was grounded, until with receptacle EGC wire was added and that there is actually another return-to-source electrical path happening somewhere else that is actually providing a short circuit path for the failure in the water heater circuit or load itself.
 

Little Bill

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Tennessee NEC:2017
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Semi-Retired Electrician
Little Bill, when I read the OP, I got the sequence just the opposite. The receptacle EGC was added from a formerly two-wire-ungrounded receptacle by running a wire to a water pipe ASSUMING the water pipe was a good ground. The OP reads to me saying that before this change, the water heater OCPD ran just fine. After adding the receptacle EGC wire caused the water heater breaker to trip.

That is to say, in my suspicion, the water pipe never was grounded, until with receptacle EGC wire was added and that there is actually another return-to-source electrical path happening somewhere else that is actually providing a short circuit path for the failure in the water heater circuit or load itself.

If you start with nothing and add nothing, the net result would be.....nothing!:)

Which is what you would have if the pipe was not grounded and you just ran a wire from it as an EGC to a receptacle. The receptacle still would not have a ground (EGC). So I'm not seeing how adding the wire would introduce a fault path back to the water heater.
Unless the receptacle was on a circuit that someone had bootlegged a ground and that was feeding back through the new receptacle, then to the pipe, and on to the faulted water heater.

I wish the OP would report back as to what he found!!!:happyyes:
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Unless the receptacle was on a circuit that someone had bootlegged a ground (or a ground already existed but was not understood) and that was feeding back through the new receptacle, then to the pipe, and on to the faulted water heater.
The hints in the language of the OP and his profile lead me to this. . . I could easily be mistaken, however.

I wish the OP would report back as to what he found!!!:happyyes:
Yes. I agree with you.
 

kwired

Electron manager
Location
NE Nebraska
That is to say, in my suspicion, the water pipe never was grounded, until with receptacle EGC wire was added and that there is actually another return-to-source electrical path happening somewhere else that is actually providing a short circuit path for the failure in the water heater circuit or load itself.
My vote is on this. The plugged in appliance or whatever, is where the return path is to something else that is bonded, the water pipe was probably not bonded and there was a fault in the water heater all along.
 
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