Stray voltage on pool pavers

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beachwiring

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Hi everyone
I recently received a call from a homeowner who has a home built 3 years ago and an in ground pool installed 1 year ago. This summer his kids were noticing a shock when getting out of the pool. He called the original electrician who basically said it passed all inspections Im not responsible and he also called the local utility company who checked their connections and ran resistance tests and told him the bonding wire was compromised. I was called in and ran resistance and voltage tests to all pool equipment and ladder cups saw around 5 ohms and 2 volts between ground and ladder cups. I ran a new bond wire from the pool equipment 30 feet away to the first pool cup retested and everything went back to 0. All pool equipment, pool water and all metal cups holding in the 3 ladders. Was wrapping up when one of my guys dropped a piece of wire into the pool as I reached into get it I felt a slight shock. I tested the wet pavers to the pool ladder and got 1.2 volts. I ran a #8 around the perimeter of the pool on the surface of the pavers back to my new bonding wire and nothing changed. Shut down his entire home and nothing changed. I drove a small ground rod in the front of the home 35' from meter and tested that to the main ground and got the same 1.2 volts. I spoke with the utility engineer and she said that is normal anything over 4 volts would be an issue and that the bond wire around the perimeter must be compromised. I told her that I didn't agree because all the cups checked out so they must be bonded together with the perimeter bond wire and that I ran a wire around the perimeter just to be sure and nothing changed. I would like to know if anyone has any guidance or knowledge to move me forward. Im thinking I may have to have the homeowner pull up the pavers and install mesh below it in order to bond the surface. Currently the pavers are about 4" thick and the bond wire is probably 6" below that. Any help would be greatly appreciated. Thank you
 
There are at least two possible origins for the voltage you see.
One is an offset between equipotential grid and remote earth because of excess current in local GES because of a compromised service neutral or POCO MGN.
Another is a voltage gradient in the surface earth because of a distribution voltage fault.

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If you shut down the entire residence then the voltage may be coming thru the ground rod or the water pipes. If this area has community water then it is possible the voltage is coming from another home. Disconnect the ground rod wire and the wire to the water pipes and see if you still have an issue
 
On things like this, I'm always curious as to if the voltage if from an on site source or an off site source. If you can read the voltage after turning off the main, it could be coming from off site. If you still have voltage with the main off, pull the service neutral and see if the voltage is still there.

If the voltage is from an on site source, IMO you should track it down.

If the voltage is from off site, I'd write a letter to the PoCo rep stating what you found. They most likely will say what they said, "normal".

If the voltage stays with main off and service neutral lifted then it's most likely a stray current through the earth and you have a step voltage showing itself.

The equipotential bonding grid is supposed to mask these problems because to find it fix it takes some work and it will most likely reappear in the future. We want cheap power, so .... fix that bonding grid.

Is the water bonded to the bonding grid?
 
Thank you guys!
oldsparky52.
-The pool is a fiberglass shell. The house is in South New Jersey along the coast so you can only go down 3-4' before you hit water. They pump out ground water for a week then drop in the pool.
-The water is bonded theres a fitting installed in the piping on each side of the pump
-I haven't lifted the service neutral. I will try that tomorrow
Dennis Alwon
-Its not community water. The house has a ufer ground and (2) ground rods I lifted each one but always left the other one hooked up and didn't see a change. I will lift both to see if that does something. The house has plastic pipe for the water service and pex for the hot and cold so the water pipes are not an issue.
GoldDigger
-I am meeting the engineer from the utility company on thursday at the house and will have her address those issues.
Thank you again. I felt like I hit a wall but now have some vigor back.
 
I am going to say insufficient permimeter bonding is your problem - even if whatever was done passed code.

Pavers within the first few feet of the edge of the pool sounds like a bad design to me for the purpose of perimeter bonding.

The idea of equipotential bonding in/around the pool is so that the users of the pool are like a "bird on a wire". Regardless of what happens or what voltage the entire pool bonding system is over remote earth - everything within reach of a pool user is at same potential. If you achieve that, the entire pool and surroundings can be sitting there at 1000 volts over a remote probe in the earth, yet nobody in the pool even knows there is any problem. 1.2 volts from the service neutral to remote probe in the earth is nothing and even sort of expected, and is a big reason why all the bonding is required in and around pools.

read 680.26(B)(2). since you have pavers you could have an alternate means that passed inspection, but is still not quite effective enough - which is why I mentioned I think the pavers within the first few feet of the edge of the poo is not a good design for the purpose of perimeter bonding. I'd be recommending at least 3 feet wide poured concrete with bonded reinforcing steel in it to the owner, cost means nothing compared to having to take a family member or friend to the cemetery in a box.

The original electrician has sort of a poor attitude if all he is concerned about is "it passed inspection so nothing is my fault".
I think he may find out in a hurry if someone would be electrocuted that if an investigation found he did have something not to code, the attorneys will come after him even if it passed inspection. He'd be wise to be involved in finding out what the problem is here even if he doesn't get paid for it. It can cost him a lot more then his lost wages should the worst ever happen.
 
I too am interested in your findings following your meeting with the power company.

The shock was not noticed after the pool's completion last year? Pool used for the first time this year?
 
1) the pool water can be a nifty battery. what type of pool water is it?
2) follow the voltage. does gradient voltage rise as you follow a path to a neighbor? maybe a neighbor N is lifted or something is compromised there?
 
FionaZuppa said:
1) the pool water can be a nifty battery. what type of pool water is it?
2) follow the voltage. does gradient voltage rise as you follow a path to a neighbor? maybe a neighbor N is lifted or something is compromised there?
Click to expand...
Those things are expected to happen and another reason why equipotential bonding is required. There shouldn't be voltage gradients within the zones where equipotential bonding is required, around the immediate perimeter of the pool is within that zone.
 
kwired said:
The original electrician has sort of a poor attitude if all he is concerned about is "it passed inspection so nothing is my fault".
I think he may find out in a hurry if someone would be electrocuted that if an investigation found he did have something not to code, the attorneys will come after him even if it passed inspection. He'd be wise to be involved in finding out what the problem is here even if he doesn't get paid for it. It can cost him a lot more then his lost wages should the worst ever happen.
Click to expand...

thank you for this.

i've seen two fatalities from incorrect pool wiring in 40 years
playing sparky.

neither was the result of anything that i had anything
to do with electrically.

to the OP.... thanks for giving a..... enough to make it right.
let us know how it turns out, and what you have to do to fix
it.
 
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I'd really like to hear the answer. It's especially interesting you still have voltage with the main off.

Is this an overhead service with a rigid mast? Do they have copper water lines?

I was involved with a similar scenario many years ago where the problem, according to utility engineer, was a broken water heater element at a neighboring house. They shut off each house individually until voltage disappeared to find the culprit.


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brantmacga said:
I'd really like to hear the answer. It's especially interesting you still have voltage with the main off.

Is this an overhead service with a rigid mast? Do they have copper water lines?

I was involved with a similar scenario many years ago where the problem, according to utility engineer, was a broken water heater element at a neighboring house. They shut off each house individually until voltage disappeared to find the culprit.


Sent from my iPhone using Tapatalk
Click to expand...
If you still have voltage with the main off that means the neutral is at a voltage higher then "ground" Since primary and secondary distribution grounded conductors are bonded together it could come from either system.

This is also a major reason we are supposed to bond nearly every metal item around a pool - no matter what voltage the premises grounding system is over true earth, the pool user is only exposed to that one potential because everything he can touch is at same potential and he is in no danger.
 
Don't forget that the shield on the incoming TV cable can also a a source of unwanted voltage. When you are disconnecting connections to the earth during testing, also disconnect the incoming TV cable.
 
cowboyjwc said:
Did they put in the required bonding ring?
Click to expand...

I have to question if a bonding ring is always going to be sufficient if the finished surface is "pavers".

I'd rather see poured concrete within the first 3 to 5 feet of the edge of the pool myself, with bonded reinforcing within it. Then maybe pavers is ok beyond that if that is what is desired.
 
kwired said:
I have to question if a bonding ring is always going to be sufficient if the finished surface is "pavers".

I'd rather see poured concrete within the first 3 to 5 feet of the edge of the pool myself, with bonded reinforcing within it. Then maybe pavers is ok beyond that if that is what is desired.
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I agree that the bonded concrete is better than the pavers.

If there is some stray current, the bonding grid is (like you have been saying) supposed to allow the safe usage of the pool and pool area. But, if there is stray current, then at the edge of the bonding grid would you once again be subject to exposure to step voltage?
 
oldsparky52 said:
I agree that the bonded concrete is better than the pavers.

If there is some stray current, the bonding grid is (like you have been saying) supposed to allow the safe usage of the pool and pool area. But, if there is stray current, then at the edge of the bonding grid would you once again be subject to exposure to step voltage?
Click to expand...
Yes, possibly. But you will be much less likely to drown as a result.
 
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