Electrical Shock In Swimming Pool

[MJ1]

We have an inground vinyl liner swimming pool with a salt generator on it.
Last August 2007, we added the generator, right after we added it, we started to notice a slight sting once in awhile.
I checked the water with a volt meter, and found out we were showing 1.5 volts in the water.
We just started noticing the voltage again a couple of days ago.
Here is what we know.
1. Pool is properly bonded and grounded.
2. Pool has a small leak, which we cannot find.
3. We have shut off power supply individually from the breaker box, and that makes no difference.
4. Only time we noticed voltage went away, is when we had a power outage.
5. Power company came out, and suspects it could be stray voltage.
6. Tested water for high concentration of metals, to see if that was a problem, but that came back negative.
7. Stray voltage, is more noticeable when ground is very dry, as the electricity is searching for a ground.

Curious if the salt is making the water more conductive, if so maybe the problem was always there, but the salt brought it to light. Concerned it is a safety issue.

Any suggestions?

 

[JohnT]

If the pool were properly bonded, you wouldn't be able to feel the stray voltage. When you added the SWCG, did you add a connection to the bond wire for it? When do you feel the shock? The most common time is when touching the water and the concrete deck around the pool, and the reason is failure to bond the rebar in the deck.

It is extremely common for pool bonding to be done incorrectly. Very few electricians really understand it.

Shutting off the power at the breaker only disconnects the hot, not the neutral and ground, both of which can cause what you are experiencing.

If in fact your pool is grounded as you say, that could be the cause of the shock.

 

[The Mermaid Queen]

welcome to TFP!

 

[CRG_80cc]

Maybe the small leak could be finding it's way to a stray voltage source. Since you have a salt generator, the salt ions are helping conduct the voltage back to your pool.

 

[Titanium]

MJ1,

I don't have much to add except to say that JohnT is spot on with his comments.

3. We have shut off power supply individually from the breaker box, and that makes no difference.

In order to determine whether the stray voltage is coming from you or others (neighbors or utility), you would have to remove the meter base. This should disconnect both the hot and neutral from the utility. I don't think this would disconnect the utility ground, though.

5. Power company came out, and suspects it could be stray voltage.

Wow, you have half the battle already won if the utiliity is already saying this. My experience is that a utility will hem and haw and stonewall and deny that stray voltage is the problem. Typically the utility will try and blame the homeowner and a improperly bonded pool. Alhough JohnT is correct - a properly bonded pool will mask the effects of stray voltage, which is exactly what its purpose is.

Can you go into more detail of 1) what the utility did, 2) what the utility said, and 3) what the utiltiy is proposing to do to correct the problem?

Also, when and under what specific conditions are you feeling the shock?

If in fact your pool is grounded as you say, that could be the cause of the shock.

JohnT, I'm confused by this statement. Can you elaborate on what you mean?

Last August 2007, we added the generator, right after we added it, we started to notice a slight sting once in awhile.

Can you go into more detail about this since this seems to correlate with the onset of shocking? Who installed the SWG? Was an electrician involved?

Titanium

 

[JohnT]

If in fact your pool is grounded as you say, that could be the cause of the shock.

JohnT, I'm confused by this statement. Can you elaborate on what you mean?

Titanium

If the pool bond wire is tied to a grounding electrode, which is required by code in Canada but not the US, this point COULD BE at a much different voltage than the pool structure or the service entrance grounding electrode. This COULD cause a current to flow resulting in a voltage gradiant. Even connecting the bond wire to the service entrance grounding electrode could still induce a flow for equipment that might have a neutral connection.

The grounding could be the cause of the voltage or it could be the means that the stray voltage is being introduced into the pool.

 

[chem geek]

Curious if the salt is making the water more conductive, if so maybe the problem was always there, but the salt brought it to light.

In addition to what others have said, what you say above is also true. Conductivity is roughly proportional to TDS so you probably increased conductivity from 2-6 times (depending on your initial TDS) when you added the salt. So any stray voltage that was there before would result in 2-6 times as much current at the higher salt level (all else equal).

Richard