swimming pool light shocking

[Proebrian]

I have a 120v pool light that you can get tingling sensation with 1 volt to earth. I have lots of experience with pools and have always been able to resolve stray voltage with correct bonding. We have checked all bonding it is correct. If you disconnect the ground wire coming from house subpanel feeding pool subpanel you loose the 1 volt at the light and the tingling sensation?

 

[don_resqcapt19]

What wire are you disconnecting to make the voltage go away? "Ground" does not mean anything in the NEC world.

 

[Luketrician]

Proebrian:

Grounded - Neutral

Grounding - EGC

 

[mgookin]

I have a 120v pool light that you can get tingling sensation with 1 volt to earth. I have lots of experience with pools and have always been able to resolve stray voltage with correct bonding. We have checked all bonding it is correct. If you disconnect the ground wire coming from house subpanel feeding pool subpanel you loose the 1 volt at the light and the tingling sensation?

Welcome to the forum.

Are you asking a question or making a statement in your last sentence?
If removing that connection results in the stray voltage going away, then it is likely that something on the house side of it is putting that stray voltage on it.

 

[Dennis Alwon]

Proebrian:

Grounded - Neutral

Grounding - EGC

Yes, Don knows that but you said ground--- not grounding or grounded.... I assume you mean you disconnected the equipment grounding conductor.

 

[Proebrian]

When i disconnect the equipment grounding conductor the stray voltage is gone. My understanding is if all metal part are bonded together it should make all the pool water,equipotenial bond on deck ect to be one potential and preventing any shock hazard. Even with a back feed on the grounding conductor

 

[Fulthrotl]

I have a 120v pool light that you can get tingling sensation with 1 volt to earth. I have lots of experience with pools and have always been able to resolve stray voltage with correct bonding. We have checked all bonding it is correct. If you disconnect the ground wire coming from house subpanel feeding pool subpanel you loose the 1 volt at the light and the tingling sensation?

is light fed from pool subpanel, or house subpanel?

does having pool pump running or not change anything?

is there a salt chlorinator, chlorine and acid pump, or anything
else 120 volt powered in contract with the pool water?

is there a gradient in the pool water, or is the tingling even
thruout the pool?

pool light incandescent, or LED?

 

[Proebrian]

It is fed from pool panel.
All breakers are off even main breaker on house.
Dont get a reading from water just when you get close to metal light ring.
Light is led.
We have ohmed out equipotenial bond to steel bond to light bond individually, it all checks good.

 

[don_resqcapt19]

When i disconnect the equipment grounding conductor the stray voltage is gone. My understanding is if all metal part are bonded together it should make all the pool water,equipotenial bond on deck ect to be one potential and preventing any shock hazard. Even with a back feed on the grounding conductor

The very fact that the voltage goes away when you disconnect the EGC proves that the bonding is not complete, because as you said, the bonding will place everything that is bonded at the same potential. When you measure the voltage, what two points are you measuring between?

 

[mgookin]

So if you break the EGC from MDP to subpanel and put a volt meter between the two, do you get 1V?
This is interesting.
Please do let us know what finally solves it.

 

[Dennis Alwon]

I agree with Don. If the main is turned off then there appears to be stray voltage. The stray voltage should be alleviated with the equipotential bonding but it does not appear to do it's job . IMO, there is something not quite right with the equipotential bonding.

 

[kwired]

The very fact that the voltage goes away when you disconnect the EGC proves that the bonding is not complete, because as you said, the bonding will place everything that is bonded at the same potential. When you measure the voltage, what two points are you measuring between?

+1

There is enough resistance in something to allow a 1 volt drop between the objects you are measuring to.

 

[don_resqcapt19]

+1

There is enough resistance in something to allow a 1 volt drop between the objects you are measuring to.

It takes a lot of current to create a 1 volt drop in short lengths of #8 copper. Of course there could be a lot of resistance in the connections. I still expect that not everything is actually bonded as required.

 

[Proebrian]

went out there to retake all the readings again. Did not find anything different , we ohmed out all the bonds to the pool steel bond all the readings were very low. we disconnected all bonds from equipment and discovered the voltage in the water by the light went to 3.5volts from the original 1volt with the bonds hooked up. So we knew the bonding was getting rid of some of the voltage but not all.We connected everything back and pulled up paver deck to find equipotential bond wire. we then ran a jumper wire from equipment bond and attached it . We got the reading down to .1 volts . seems there is some kind of deck bond issue. Just to satisfy my curiosity I disconnected and ohmed out deck bond really low reading Im baffled why it was not working but we ran a #8 bare bond to the deck bond and back to equipment bond and cleared it up.

 

[Dennis Alwon]

So it does appear to be stray voltage that was not corrected by the bonding as some of us stated. Why it didn't I do not know other than the connections somewhere were not as good as they should have been. Perhaps some corrosion had gotten in on some of the joints.

 

[GoldDigger]

If your are measuring voltage in the water itself at various points, and higher near one of the lights, then no amount of "bonding the water" will resolve that problem.
Leakage somewhere in the light seems to be getting past the equipotential bonded surfaces of the light and causing current and therefore a voltage gradient in the water.
Possibly an open bond connection in the parts of the light.

If, on the the other hand, all of the metal around and in the pool is at the same potential, then the water cannot be at any other potential.
If all of the equipotential grid around the water is at one voltage and the water is at another voltage, then something which is in contact with the water is either both unbonded and ungrounded or is unbonded but is connected to remote earth ground potential. (Like a drain fitting connected to a metal pipe but with a plastic union before it gets back to where the pipes are bonded.)

Your original description of a tingling when you touch the water and "earth" at the same time tells me that the water is at the EGC potential but the earth around the pool has not been properly made a part of the same equipotential grid.
Do you know if there is a bonded wire or mesh under the earth around the pool?

 

[Dennis Alwon]

If your are measuring voltage in the water itself at various points, and higher near one of the lights, then no amount of "bonding the water" will resolve that problem.
Leakage somewhere in the light seems to be getting past the equipotential bonded surfaces of the light and causing current and therefore a voltage gradient in the water.
Possibly an open bond connection in the parts of the light.

The op says there was voltage with the main breaker off at the house.

it is fed from pool panel.
All breakers are off even main breaker on house.

 

[GoldDigger]

The op says there was voltage with the main breaker off at the house.

In which case my later alternative of the equipotential plane being different from remote (or local) earth would come into play.
That does cause me to wonder why, with the main breaker off, the voltage near the light jumped from 1V to 3.5V when the EGC was lifted.

Possibly we have two problems here, namely
1. Leakage in the light and
2. Displacement of EGC from earth because of current drawn by another load on the same POCO secondary, POCO MGN problems, or earth gradients from wires other than house loads.

 

[kwired]

In which case my later alternative of the equipotential plane being different from remote (or local) earth would come into play.
That does cause me to wonder why, with the main breaker off, the voltage near the light jumped from 1V to 3.5V when the EGC was lifted.

Possibly we have two problems here, namely
1. Leakage in the light and
2. Displacement of EGC from earth because of current drawn by another load on the same POCO secondary, POCO MGN problems, or earth gradients from wires other than house loads.

OP said in post 1 that when EGC to pool subpnel light was lifted the 1 volt went away. He later said when disconnecting some of the other equipment bonds, the voltage raised to 3.5 volts.

 

[GoldDigger]

OP said in post 1 that when EGC to pool subpnel light was lifted the 1 volt went away. He later said when disconnecting some of the other equipment bonds, the voltage raised to 3.5 volts.

Let ,e try to clarify that a little:

He said

If you disconnect the ground wire coming from house subpanel feeding pool subpanel

The 1V measured between the pool light and local earth went away.
Nothing about a pool subpanel light. I am assuming that the "120V light" is a pool light, not a light at the panel.

Anyway, in the absence of any other information, I would first consider that the EGC is effectively bonded to the light shell in the water, but that there is a tingling due to the voltage difference between the water and the earth around the pool.
Two ways to approach that:

1. Figure out why the EGC is 1V off local ground (there are any number of code compliant reasons for that given neutral current flowing in/out of the GES somewhere, not necessarily at the house in question. Fix that somehow.
2. Figure out why the local earth around the pool is not part of the equipotential grid connected to the EGC.
The second one is probably more valuable in the long run.

The information about 1V --> 3.5V with some combination of bond lifts is more unclear and possibly not relevant to this problem except to the extent that it affects point #2 above.

Does that fit with your understanding of the OP's posts?