swimming pool light shocking

[kwired]

Let ,e try to clarify that a little:

He said
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?

OP did mention the 1 volt to earth. Did not mention where in relation to the pool this "earth measurement point" was. Considering the intended purpose of using equipotential bonding in and around a pool, this measurement needs to be taken very near the pool. Any measurement to earth away from the pool doesn't mean much and some voltage reading to a remote point may actually be considered normal.

Would seem to me the most important measurement here is likely from the light in question to either the water, or other conductive objects nearby (in or out of the water) like say a exit ladder or structure for diving platforms, lifeguard stands, and the like.

 

[GoldDigger]

OP did mention the 1 volt to earth. Did not mention where in relation to the pool this "earth measurement point" was. Considering the intended purpose of using equipotential bonding in and around a pool, this measurement needs to be taken very near the pool. Any measurement to earth away from the pool doesn't mean much and some voltage reading to a remote point may actually be considered normal.

Would seem to me the most important measurement here is likely from the light in question to either the water, or other conductive objects nearby (in or out of the water) like say a exit ladder or structure for diving platforms, lifeguard stands, and the like.

Given the OP's statement about tingling in addition to measurement, I suspect that the potential difference driving that is between the water near the light and earth within easy reach alongside the pool. Earth in that area should be protected by the EP grid.

You can exit the pool anywhere along the side, not just at a ladder, unless the water level is very low.

 

[kwired]

Given the OP's statement about tingling in addition to measurement, I suspect that the potential difference driving that is between the water near the light and earth within easy reach alongside the pool. Earth in that area should be protected by the EP grid.

You can exit the pool anywhere along the side, not just at a ladder, unless the water level is very low.

My main point was we don't know what the "to earth" was a reference to.

We also don't know what conditions users may have been experiencing the tingling to. Was it just felt in the water, or did they have to touch something else that is within reach? Did they have to touch the light or just be close to it? Knowing how well or if the concrete reinforcement is even bonded is going to be nearly impossible I would think.

 

[Pool]

Water inside

Water inside

If there is water inside the fixture it may need to dry out or be replaced. I have a scare near my thumbnail that picks up this tingle feeling as it gets close to some fixtures. Feels like a stick pin.

 

[kwired]

If there is water inside the fixture it may need to dry out or be replaced. I have a scare near my thumbnail that picks up this tingle feeling as it gets close to some fixtures. Feels like a stick pin.

Wet niche fixtures get water inside the niche. If water makes it's way into something that is supposed to be sealed and there is current leakage - GFCI protection should trip.

OP is dealing with a bonding and grounding issue