pool grounding once again

[aj30fan]

I have read through almost every post here but still cannot find any information on how to correct stray voltages or even where to begin.I have a situation where a small .5 to 1 volt appears on the grounding grid and gets into the pool, Ive spent weeks checking everything and cannot determine where this voltage is coming from.Ive exhausted all options that I can think of...called public service to check incoming, ran new feeds to pump, drove additional ground rod at panel(maybe I lost a ground there)but nothing seems to work.Any help on where to go next?

 

[bphgravity]

Re: pool grounding once again

Mike Holt has provided lots and lots of information on this exact subject. Try the link below and read the newsletter articles on the subject of stray voltage. You will see that there are many variables that can lead to this problem.

It is possibly more of a bonding problem than it is a grounding problem. If a metallic component of the pool has not been properly bonded, it could create a potential between another conductive component like the pool water. On the other hand, there could be an issue of an open or bad neutral connection at the home or a neighboring home that is using the pool as a return path.

Check out the link and see if you get some help there.
Try this Link

 

[charlie]

Re: pool grounding once again

I hate to say this but if everything is properly bonded to a #8 Br. Cu., the problem may very well be the serving electric utility. If a trouble man comes out and says it is your problem, call the engineering department and ask for a reference to their power quality or load and voltage people. You want someone out there with sensitive meters that know what they are doing. A trouble man is great if the problem is simple but they can't do in depth analysis.

 

[hurk27]

Re: pool grounding once again

A voltage drop on the service neutral from the transformer would easly have a .5 to 1 volt differantal between the pool grid and Earth? But why is this a problem? I can't see any one being able to feel a shock from that low of a voltage?

How are you messureing this voltage? are you placeing a short rod in the Earth a few feet away from the pool and messuring the voltage from it? Is there is a concrete surface close to the pool that is not bonded, or the voltage to Earth is higher?

I have seen where a primary neutral loss caused 56 volts to be on all the grounding of a apartment building to Earth that had no metal water pipe. This was because the transformer was pulling it's return voltage from the buildings grounding electrode system which was only a single ground rod.

 

[aj30fan]

Re: pool grounding once again

originally that was exactly what I was getting 56 volts across the entire system.I called public service and they replaced the nuetral off the street and brought the voltage down so I thought everything would be ok, a couple of days later I got another call saying they were still getting shocked when exiting the pool.I stuck one lead of my fluke in the pool and the other into the ground and read 1.7 volts.That must be what there feeling, pool is bonded correctly passed inspection, cant figure anything other than stray voltage, but now the hard part of trying to fix it.