Bonding two sections of copper pipe with PEX between them?

I felt current when I was washing my hands on several occasions when the vanity light switch was on. I later discovered that I only felt the current when I was using hot/warm water, which is the pipe that the box was touching. I didn't feel it if only the cold water was on. I also do not recall getting "zapped" when using that sink prior to adding PEX to supply that bath. AFAIK, nothing electrical changed with that circuit. It is entirely possible, however, that the copper pipe shifted slightly when I reconnected the water and made contact with the electrical box.

I don't think I was touching anything else. I do not recall if I had shoes on or not. This is a basement bath, carpet/pad on slab

In addition to adding the bonding jumpers around the PEX as recommended, be sure to add a bonding jumper from the metal hot water pipes to the metal cold water pipes. This is usually done at the hot water heater on the pipe side of the water heater fittings/flexible lines.

Hot water heaters have "dielectric unions" and other parts which prevent a contiguous electrical connection from the cold water pipes to the hot water pipes. So this is why it is necessary to install a bonding jumper.

Lets go back a second to all the piping being copper. Lets say there is a high resistance short inside the box. Its a high resistance short so the breaker doesn't trip but there is power flowing from hot to ground. Ok, now you cut out part of the copper pipe and replace it with pex effectively defeating the bonding of the copper pipe at the panel. Now when you use the water you get a shock. You discover that the box is touching the copper pipe, you move it and then no more shocks.

One or more of the following is therefore true. 1) The box is not grounded. If it was you would have still had a path back to the panel so you would have not been shocked. 2)The ground wire has a break in it or is not connected someplace so essentially the box is not grounded. 3) When measuring the voltage between the white wire (neutral) and the ground wire the voltage is not 0. 4 When measuring voltage between hot and neutral and then hot and ground you get different readings. They should be around 120V, but its more important that the readings are the same.

-rick

Billy_Bob said:

In addition to adding the bonding jumpers around the PEX as recommended, be sure to add a bonding jumper from the metal hot water pipes to the metal cold water pipes. This is usually done at the hot water heater on the pipe side of the water heater fittings/flexible lines.

Hot water heaters have "dielectric unions" and other parts which prevent a contiguous electrical connection from the cold water pipes to the hot water pipes. So this is why it is necessary to install a bonding jumper.

Click to expand...

I have a jumper at the water heater which is also near the water service entrance. Its a gas water heater, btw.

BimmerRacer said:

I have a jumper at the water heater which is also near the water service entrance. Its a gas water heater, btw.

Click to expand...

Good! (Safer)

FYI "dielectric unions" are used on gas or electric water heaters. Here is a bit on that...

drick said:

Lets go back a second to all the piping being copper. Lets say there is a high resistance short inside the box. Its a high resistance short so the breaker doesn't trip but there is power flowing from hot to ground. Ok, now you cut out part of the copper pipe and replace it with pex effectively defeating the bonding of the copper pipe at the panel. Now when you use the water you get a shock. You discover that the box is touching the copper pipe, you move it and then no more shocks.

One or more of the following is therefore true. 1) The box is not grounded. If it was you would have still had a path back to the panel so you would have not been shocked. 2)The ground wire has a break in it or is not connected someplace so essentially the box is not grounded. 3) When measuring the voltage between the white wire (neutral) and the ground wire the voltage is not 0. 4 When measuring voltage between hot and neutral and then hot and ground you get different readings. They should be around 120V, but its more important that the readings are the same.

-rick

Click to expand...

I connected an outlet to that wire and used a 3 wire plug in tester which didn't show anything as being wrong. No open ground, etc. I used a multimeter to measure hot to neutral and hot to ground and got the same reading. Neutral to ground shows 0.

You keep bring up dielectric unions, but I dont see how they apply in my case. I have yet to see a dielectric union for copper/pex and I don't see where it would be applicable for the water heater either

So far as this discussion, it's not important if you have those unions or not, I'm just trying to point out that sometimes one section of pipe will be electrically isolated from another section of pipe. Sometimes not.

Here is a water meter which might not be electrically conductive (fittings?) and they installed a bonding jumper to be sure of a contiguous electrical connection...





Here they are installing a bonding jumper between the hot and cold water pipes above a traditional water heater tank...



Here there are several different pipes and they have electrically bonded them all together...

Bimmer

Forget all this hog wash about bonding the pipes in your home. Read the Panel statement from the proposal above and you will see that those charged with writing the NEC seems to think all this bonding around this and that is nothing more than hog wash also.

The only place that bonding of a water pipe is important is if you have 10 feet or more in contact with earth which would make it a grounding electrode. I have already covered what the purpose of an electrode is so I won’t rehash that.

In order for current to flow there must be a complete path from the source back to the source just as in any flashlight. Current leaves the battery goes through the conductor of the flashlight through the bulb back to the battery.

If you were feeling a shock from the water there would have had to been a complete path from the transformer supplying your home back to the transformer.

If the metal box was properly bonded to the equipment grounding conductor then any and all current would have had a path back to the source which would have opened the overcurrent device.

If the box was not properly bonded and there was a problem with the light fixture then it is possible that current was entering the water pipe through the box and through your body down to the concrete back on the grounding electrode conductor and completing the path to the source. When you removed the fixture and box you cleared the fault.

When reinstalling the fixture check that the equipment grounding is connected to any and all metal and check the fixture for any failure. Corrosion of the interior of the light could be your problem

JW - go read the WA State post on the Pro forum.

jwelectric said:

Bimmer

Forget all this hog wash about bonding the pipes in your home. Read the Panel statement from the proposal above and you will see that those charged with writing the NEC seems to think all this bonding around this and that is nothing more than hog wash also.

The only place that bonding of a water pipe is important is if you have 10 feet or more in contact with earth which would make it a grounding electrode. I have already covered what the purpose of an electrode is so I won’t rehash that.

In order for current to flow there must be a complete path from the source back to the source just as in any flashlight. Current leaves the battery goes through the conductor of the flashlight through the bulb back to the battery.

If you were feeling a shock from the water there would have had to been a complete path from the transformer supplying your home back to the transformer.

If the metal box was properly bonded to the equipment grounding conductor then any and all current would have had a path back to the source which would have opened the overcurrent device.

If the box was not properly bonded and there was a problem with the light fixture then it is possible that current was entering the water pipe through the box and through your body down to the concrete back on the grounding electrode conductor and completing the path to the source. When you removed the fixture and box you cleared the fault.

When reinstalling the fixture check that the equipment grounding is connected to any and all metal and check the fixture for any failure. Corrosion of the interior of the light could be your problem

Click to expand...

Thanks. There was no fixture there at the time, but the ground wire did have some oxidation on it. I think my plan when I do reinstall the fixture would be to use a plastic box and make sure all the connections and wires look good.

Thanks drick!

I'll post the link...

Washington to impose fine on plumbers that repipe houses without maintaining the ground or bonding...
https://terrylove.com/forums/showthread.php?34724-Heads-up-for-Washington-State-Plumbers

What an electrical inspector has to say about this (see post 12 and others)...
(Also ask your local electrical inspector and see what he says.)
https://terrylove.com/forums/showthread.php?33622-Gas-water-heater-ground&daysprune=60

Billy_Bob said:

Thanks drick!

I'll post the link...

Washington to impose fine on plumbers that repipe houses without maintaining the ground or bonding...
https://terrylove.com/forums/showthread.php?34724-Heads-up-for-Washington-State-Plumbers

What an electrical inspector has to say about this (see post 12 and others)...
(Also ask your local electrical inspector and see what he says.)
https://terrylove.com/forums/showthread.php?33622-Gas-water-heater-ground&daysprune=60

Click to expand...

drick said:

JW - go read the WA State post on the Pro forum.

Click to expand...

i wonder how far it is from the State of Washington and Washington DC?

I also wonder what the Washington State amended rule has to do with the NEC.

This is an open discussion forum where most give answers based on the NEC instead of expecting everyone to know the local amendments of every jurisdiction throughout the country.

This bull of bonding every piece of pipe in a building shows the lack of understanding of those trying to shove all this junk down the throats of those who have a full understanding of current flow.

Most don’t understand if there is nothing electrical connected to a metal pipe there is no way the pipe can become energized although some think it is a mysterious phenomenon that takes place and a danger to everyone’s life somehow establishes itself if the pipes are not electrically continuous. This thinking is nothing short of coming from the anal canal of a bull.

Some even argue that the connection of metal water pipes to the electrical system puts those working on the pipe in more danger than if they were left free.
Case in point: the metal water pipe is also the grounding electrode or in other words there is 10 feet or more in direct contact with earth and a plumber has to do a repair on this pipe. If the service has lost its grounded neutral somewhere then the metal water pipe will be energized and, no, it will not open anything except for that poor plumber’s heart when he becomes the path. If the pipe had not have been connected to the electrical service in the first place then the plumber would be in no danger what so ever.

One last comment on this matter. The electrical inspectors do not write the codes. I agree that it is a good idea to talk with the inspector, but, if they are wrong then you are wrong also and the liability will always land in your lap. Make sure that you are abiding by the codes even if the inspector disagrees with you.

A little food for thought……….

Most people who are addressing questions such as in this thread only have limited knowledge about residential or small commercial electrical systems and base their comments on what they have been told or read about these systems. They have never widened their knowledge to systems that have high-impedance grounds or even corner grounded delta systems.

They are quick to make comments and post links to what others have made comments about but don’t have the first hand knowledge for their self.

Most don’t have an understanding of current flow nor will they open their minds to try to understand how current reacts in different scenarios. They just try to prove their points by posting links to what others have to say no matter if that link is correct or not.

When I pull out of my driveway I can accelerate to 55 MPH. I have driven at 55 MPH past the school house a couple of miles down the road and did not get a ticket. Does this mean that I can drive past this school during the times that school is taken in or is being let out at 55 MPH? Maybe I should call the inspector and find out.