pool frame has volts!

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nankipoot

nankipoot

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I have a customer that says they get a shock when in their inground pool when touching the frame. He said they checked it with a volt meter and it reads 2 volts. The pool has a ground ring wire around the perimeter atttached to the pool and back to the motors.

The volts DO NOT Go AWAY when the main is turned off. Only when the meter is pulled. Or so they tell me, ( that make no #$!@#$ right)

I told him to check if it had a three or four wire feed, and remove the light shell feed. ( I thought that might be it but I don't know, The main off and still volts, Hmmmm)

Things they tried :

Installed ground rod at the motors to pool ring wire. ( I hear alot of people doing this and doesn't that open the unequel potential can of worms ?)

Had power co come and check grnd rod at service and pole.


Any ideas
 
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Where are you reading this voltage from??? The pool and what? IF you are reading 2 volts between the pool and a ground rod it is likely you have a full 120 or more on the pool. You said this is an inground pool. What is around it concrete? I am trying to picture this.
 
Even with the meter pulled there is still a neutral connection providing a path back to source.

edit: misread op. voltage goes away when meter is pulled.
 
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The part i would check first is why with meter out it goes away but main breaker it doesnt.Any chance they have a neutral problem ?
Would take good ohm meter and measure between the 2 points he is measuring the volts.Is this customer an electrician ? if not he should hire one that does pools.What exactly are you refering to as the FRAME ?pool cage ?
 
I had a similar call about six years ago. I (up until this housing/mortgage trouble) did many pools, so I was referred by a pool builder who took the call. Customer said they were getting a "tingle" when they touched the pool water from the deck. Ever the skeptic, I checked the pool water to deck voltage and it was about 6V! Turned main breaker off and it was still there. I checked bonding wires, EGC, etc. to no avail. I told the owner to call and report the problem to the local utility, which they did. I followed up a week later and was told that the utility crew spent a day and couldn't find the source, so they sent out a testing service. Turns out the testing crew drove two more ground rods and connected them to the service and the problem was fixed.

... at least that is what the owner told me.


- Greg
 
mikeames said:
Where are you reading this voltage from??? The pool and what? IF you are reading 2 volts between the pool and a ground rod it is likely you have a full 120 or more on the pool. You said this is an inground pool. What is around it concrete? I am trying to picture this.
Click to expand...

I have not been to the location, but plan to. I am told the pool has concrett all around (with full bonding) , and method was metal edge to earth. Actually the customer said when children are in the water they get a jolt when they touch any metal edge. ( I think thats what I would call the liner rail ) They said it does it mostly at locations where the paint has worn off the metal.
 
Jim W in Tampa said:
The part i would check first is why with meter out it goes away but main breaker it doesnt.Any chance they have a neutral problem ?
Would take good ohm meter and measure between the 2 points he is measuring the volts.Is this customer an electrician ? if not he should hire one that does pools.What exactly are you refering to as the FRAME ?pool cage ?
Click to expand...

A loose neutral can cause weird stuff. I agree, I just cant see how pulling meter would do anything that throwing the main would not. I plan on seeing that for myself.

Thanks everyone for the input I'll post back what or if we find.

If any other ideas please post
 
I didn't hear you mention an 'Equipotenial Bonding Grid" as required by NEC

680.26. If everything was bonded, including the EBG under the cement apron,

then even if there was a small voltage present, it would not be felt. It can

only be felt when there is a potential difference.
 
I believe it has to be more than 2 volts. Even when wet, you wont feel 2 volts. Imagine holding on to a 9 volt battery in the pool..Will you feel it? I dont think so. 2 volts is what the meter is reading due to a poor connection but a full human body has a lot of surface area in the water, and cuts across a lot of voltage gradients between the source and the metal edge.

I believe there is a voltage present which makes it serious and an urgent find.
 
nankipoot said:
A loose neutral can cause weird stuff. I agree, I just cant see how pulling meter would do anything that throwing the main would not. I plan on seeing that for myself.

Thanks everyone for the input I'll post back what or if we find.

If any other ideas please post
Click to expand...

Pulling meter might just be accidently moving the neutral enough to work.Would check all connections and ground clamps/wires.Sounds like fun day.
 
mikeames said:
I believe it has to be more than 2 volts. Even when wet, you wont feel 2 volts. Imagine holding on to a 9 volt battery in the pool..Will you feel it? I dont think so. 2 volts is what the meter is reading due to a poor connection but a full human body has a lot of surface area in the water, and cuts across a lot of voltage gradients between the source and the metal edge.

I believe there is a voltage present which makes it serious and an urgent find.
Click to expand...

Mike, It has more to do with the 60Hz than the amount of voltage, and as you

know only 0.3 to 0.4 mA to feel the sensation of electricity.
 
Ok yea .03 -.04 amps but that wont flow if the voltage cant overcome the sum resistance of body and water.

I agree 60 cycle power is different than flat DC but 2 volts of either is still not enough.

With 2 volts and .01 amps flowing (less than the .03 or .04) you have a circuit resistance of 200 ohms. Thats well below the total resistance of a wet body and the pool water. Thus the reason I feel there is a much higher stray voltage somewhere that needs to be found before someone gets hurt or killed.
 
plugging in the meter connects/provides a return path to the poco source. One possibility is that this is a low impedance path, and that as emahler indicated, there is a poco source (so called stray voltage which could be a neighbor having a poor neutral, or another poco unintended source) which is using this path to return to source. I confess that I don't understand why the mechanics of this would create a voltage gradient at the pool, but there are other documented cases of this (one such story of stray voltage under a pool was in one of Mr Holt's newsletters last year I believe). At any rate, this is one possibility to consider while you try to figure this out.
 
Some one posted a report by Georgia Tech on pools grounding and bonding. I don't have a link but I dd download it in PDF, it is about 25 pages. If you send me a PM with your e-mail I will forward it to you. On page 10 it states a case where 1.7 to 2 volts was measured between the pool water and the ground ring. When a copper butt plate was connected to #8 wire and the ground ring then dropped in the water the voltage dropped to zero. this sounds like a similar case, nothing bonded in the water to the equalize the potential difference of the water and the metal pool edge.
 
This sounds interesting. I just have a real hard time believing you could feel the current from 2 volts. I know others will disagree with me but I have a hard time believing its just a slight difference between the water and ground ring.

If the above situation is the case here then would it be safe to assume that this pool does not have a metal pool ladder connected to the grid?
 
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