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Old 01-11-2012, 06:01 PM   #1
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Voltage in the Shower


I'm new to the forums and joined because of a puzzling electrical issue in my home. Please note I'm not particularly educated in electrical matters, so please excuse any terminology issues. Also note that I've sought professional help in the matter from an electrician, who happens to be stumped. Any thoughts would be appreciated.

Background
The problem I'm dealing with is that the other morning in our tub shower I clearly felt current when I touched the hot/cold taps to adjust the temperature. At the time I was in the shower (i.e., wet). This freaked me out. It's a new issue and no work has been done to our house recently. After some preliminary online research I called my utility. They came to the house and tested everything and said it was nothing on their end (my entire service loop was replaced last year). Subsequently, an electrician came to the house. He checked all of the ground wires and made sure everything was well grounded (it was). He then took his voltmeter into the bathroom and measured 28-30V on the shower door (sliding glass door with brass frame sitting on the tub) but NOT on the taps where I had felt it previously. Removing the screws that anchor the shower door into the wall changed nothing. We shut off the breakers in the sub panel and isolated the circuit that was the issue. We then isolated the issue further to the switch leg in my bathroom. It's a dimmer switch and there was a direct correlation between the voltage reading and where the dimmer switch was set. Finally, turning on the tap water and switching the water diverter to the shower setting charged up the taps. The theory we came up with was that a wire was somehow sitting on the water pipes or was worn and arcing over to it. Water and the copper pipes were carrying the charge. My electrician believes it's an issue with the neutral (floating neutral? - I'm not really sure what this is).

Stage 2
The electrician came over this morning and the mystery deepened. First, the problem disappeared entirely - the voltmeter reads zero no matter what we try. Nothing was done whatsoever in the interim and we tried everything to get it to return (all switches on in the house, ran the water, etc.). Second, based on how my bathroom is laid out and an investigation of the crawl space, our belief is that the wiring and water pipes do not run next to each other in the bathroom. It seemed like an issue local to my bathroom but this belief would suggest something else is going on.

The one remaining theory we are going to test tonight is that it is somehow being caused by one of my neighbors. The issue has shown up early morning and in the evening - ie, when lots of lights are on - and nothing we do here is making it come back.

Sorry for the long post. Any thoughts or theories would be much appreciated. Thank you!

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Old 01-11-2012, 06:32 PM   #2
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Voltage in the Shower


If there is voltage on the grounding electrode system the plumbing pipes could be energized.

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Old 01-11-2012, 06:37 PM   #3
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Voltage in the Shower


I'm not sure since an electrician and the utility have been out to investigate. Let me ask you a few questions

1.) Do you have an electric hot water tank ?

2.) Brric asked my second question
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Old 01-11-2012, 06:47 PM   #4
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Thanks for the thoughts. We have a gas water heater. I'm not sure entirely what you mean by voltage on the grounding electrode system but there was no voltage reading on the outside ground rod, water main, on the water tank etc. The only place we got any reading was on the shower and that was directly correlated to the local switch in the bathroom. I hope that helps.
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Old 01-11-2012, 07:10 PM   #5
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Voltage in the Shower


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Originally Posted by Deacon98 View Post
The only place we got any reading was on the shower...
do you have pex piping? or some other NON metallic pipe?

...and that was directly correlated to the local switch in the bathroom.
how are you so certain that this "correlation" is limited like this?
somehow... the electricity has bridged itself over.

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I'm not sure entirely what you mean by voltage on the grounding electrode system... but there was no voltage reading on the outside ground rod, water main, on the water tank etc.
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Old 01-11-2012, 07:30 PM   #6
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Yes, there is some non-metallic piping. Looks like PVC drain pipe at a minimum. I haven't looked thoroughly to know what is and isn't metallic at this point. Could this be involved somehow?
Determining the correlation between the switch and the voltage was straightforward - look at the reading on the voltmeter when the switch was on and off. It's actually a dimmer switch so you could see the voltage gradually going from zero to 28V as the switch was gradually increased. When the switch was off, there was no reading whatsoever. The only time we got a reading was when the lights in the bathroom were on. There is a fan in the bathroom too (separate switch) and this had no impact.
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Old 01-11-2012, 07:37 PM   #7
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Voltage in the Shower


sounds like you might need to do some wire tracing .
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Old 01-11-2012, 07:40 PM   #8
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Yes, there is some non-metallic piping. Looks like PVC drain pipe at a minimum. I haven't looked thoroughly to know what is and isn't metallic at this point. Could this be involved somehow?
No; which is why I asked the question.

The underlying assumption is that your home has copper pipe throughout.
That this pipe is bonded to the overall grounding.
(whatever you did or didn't find at the ground rod)

Quote:
Determining the correlation between the switch and the voltage was straightforward - look at the reading on the voltmeter when the switch was on and off ... When the switch was off, there was no reading whatsoever.
Are any of these feed or switchleg electrical wires in contact with the water pipes?
(in immediate proximity to the shower or anywhere else)
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Old 01-11-2012, 07:42 PM   #9
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Voltage in the Shower


You said the electrician isolated the problem to the "switch leg" and also said the light is on a dimmer. Does the power from the panel run to the light first or does it go to the switch first?

I'm assuming the electrician knows what he is doing but just want to confirm that the dimmer isn't using the ground as a neutral which is a no-no.
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Old 01-11-2012, 07:49 PM   #10
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Voltage in the Shower


even if a raw copper ground it touching a neutral within any switch if it is going out as BX running over a copper pipe.the entire copper water system is getting the white neutral hit...is the house BX or romex runs?
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Old 01-11-2012, 07:50 PM   #11
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Quote:
Originally Posted by TarheelTerp View Post
No;
Are any of these feed or switchleg electrical wires in contact with the water pipes?
(in immediate proximity to the shower or anywhere else)
It's unclear whether this is the case or not but the bathroom layout and logic would suggest this isn't the case. Also, why did the problem disappear entirely? It doesn't make sense. Thanks for the continued thoughts.
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Old 01-11-2012, 07:51 PM   #12
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Voltage in the Shower


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Originally Posted by <*(((>< View Post
You said the electrician isolated the problem to the "switch leg" and also said the light is on a dimmer. Does the power from the panel run to the light first or does it go to the switch first?

I'm assuming the electrician knows what he is doing but just want to confirm that the dimmer isn't using the ground as a neutral which is a no-no.
He opened up the switch box and said everything looked in order. That's all I know. I will ask him when he comes over again tonight. Thanks for the thought.
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Old 01-11-2012, 07:53 PM   #13
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even if a raw copper ground it touching a neutral within any switch if it is going out as BX running over a copper pipe.the entire copper water system is getting the white neutral hit...is the house BX or romex runs?
Your question is beyond my level of education about this stuff but I will ask the electrician tonight. Sorry I can't be of more help. Thanks for the reply.
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Old 01-11-2012, 08:26 PM   #14
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Voltage in the Shower


get yourself a buzzer that will work with 24Vs and hook it up to the shower knobs and go around switching the entire house or as you have narrowing it down.did anybody take the raw copper grounds that land back to the circuit breaker panel and remove one at a time and test them each to the panel or grounding bar during a voltage read at the knobs...might want to try electricantalk on this one
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Old 01-11-2012, 08:49 PM   #15
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get yourself a buzzer that will work with 24Vs and hook it up to the shower knobs and go around switching the entire house or as you have narrowing it down.did anybody take the raw copper grounds that land back to the circuit breaker panel and remove one at a time and test them each to the panel or grounding bar during a voltage read at the knobs...might want to try electricantalk on this one
Thanks. The electrician did all of that and it checks out. He just left and tested everything. The problem has disappeared, which is disconcerting. His prevailing thought is that there's back feed on the neutral and this may be coming from a neighbors house. It does not make sense that the problem went away entirely when nothing has been done.

Many thanks for the ideas.

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