in-ground pool bonding issues...

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UpEvol

Member
I am troubleshooting an in-ground pool that is more than likely pretty old. There is a bond for the equipment going into the earth (#8 bare). I am assuming there is a loop around the pool based on the pool guys knowledge with this property. The 2 niche lights are low voltage and were replaced recently.
My concern is that the homeowner says he is still getting "shocked" when he is in the pool. The only metal is the drain, and the rings for the lights. I ran a jumper to the #8 bare in the equipment area and put my meter between the ground and the water - it fluctuated voltage between .5 and 3 volts...
So, is this a bonding issue, or could there be a wire buried close by with an exposed hot, or a neutral back-feeding from somewhere? Also I shut down all the mains for the property while testing with no change in readings...
Any help will be appreciated...
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
If all the mains are off and thee is still voltage, then I suspect it is coming from the utility underground cables. If the bonding was done properly you should not feel the voltage. I would contact the poco and see what they could do.
 

UpEvol

Member
Thank-you dennis. I have considered that and will be calling them. Could there be an issue coming from the neighbors pool or equipment? The pools and gear are about 15 or 20 feet apart...
 

wirenut1980

Senior Member
Location
Plainfield, IN
With the main off, remove the neutral connection coming from the utility and check voltage again between water and ground. If it is still there the source is most likely current in the ground coming from either a secondary fault from the neighbors, or if utility primary underground cables are in the area, could possibly be an open primary neutral. If this is the case, the source should be found.

If the voltage goes away when lifting the neutral at the main, then the voltage is voltage drop on the primary neutral. If this is the case, there is probably nothing the utility can do, since 0.5 to 3 V is considered normal.

I agree with Dennis that the bonding is not correct if the voltage is still felt. My knowledge is limited on how to properly bond an existing older pool.
 

M. D.

Senior Member

UpEvol

Member
UPDATE...

UPDATE...

Thank you for the replies, and links.
Today I started snooping around the neighbors property... The pool equipment for both pools is separated by a 6' brick fence. everything associated with the two pools is about 15' apart. I took a reading at the neighbors pool and came up with .2v.
A new pump was installed last week and was not bonded. I bonded the pump, and the pool zeroed out for about 20 minutes and then went back to a 1.5v reading (I suspect the pump is shaking the ground wire loose).
Just to see what would happen I bonded the two grounding systems together with a #6 jumper...
both pools immediately zeroed out, then remained steady at .1v

I would love to say problem solved, but I have only eliminated the symptom...
There are more potentials between the two properties I am sure, given the fluctuations when things like pumps and A.C. units turn on and off.
I would rather not leave the two pools bonded together even though the homeowners are fine with it...
Have I introduced a new world of problems that could potentially be more serious to both homeowners? How do I eliminate the source if it does not seem to be from either property, and the power co. considers it normal?Perhaps I am over thinking this, but I would like to be sure the problem has been resolved.

Thanks again for all your help...
 

M. D.

Senior Member
If there is a stray current issue there will be higher readings as the usage in the neighborhood goes up .. try going there when the people in the hood are home like a saturday , a hot one,. when A.C's are running and folks are washing clothes and such ... the readings will most likely go up.. If these neighbors are friendly you could have them both turn on electric loads and see what happens.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I would ask the neighbors to turn off their power and take readings. Also if the water is a community system then anything goes.

In terms of a band aid, th EPB system is really a bandaid-- it basically allows stray current but you will not feel them. I would do the fix that works and leave it at that. Trying to eliminate all currents may be impossible.
 

UpEvol

Member
Thanks guys. Your comments make a lot of sense after reading the links posted by M.D. earlier... although the equipotential grid test conducted showed surprising results contradicting other theories concerning the issues in 547 and 680. Perhaps the old saying "it if works, don't fix it" still has some value...

Thanks for the help.
 

wirenut1980

Senior Member
Location
Plainfield, IN
Thought I'd post a link or two ... to bond an already installed pool area is very expensive... You will most likely need to scroll way down to see the article ,. I had to.
http://ecmweb.com/construction/swimming-pool-bonding-requirements-20101101/

http://donaldwzipse.com/images/PID642277.pdf
And this one is kinda big .. it's got lots of pictures .. and it was used in the EC&M article
http://grouper.ieee.org/groups/td/d...Results-EPRI-Swimming-Pool-Test-Structure.pdf
Good luck !

Anybody notice that the Donald Zipse paper says that the equipotential bonding grid is useless and does not work against stray voltage...err current?:happysad:
 

M. D.

Senior Member
Anybody notice that the Donald Zipse paper says that the equipotential bonding grid is useless and does not work against stray voltage...err current?:happysad:

Yup , I'm Just a guy , an average guy not very well educated ,. but whe he says things like this ,. it makes sense to me

It is opined that the equipotential plane is no more than an earth electrode, which lacks any ability to maintain or to have zero voltage gradient across it when any amount of electrical current flows over, across or through the equipotential plane. As an electrode-earthing element, the equipotential plane has the potential for uncontrolled stray current from the multigrounded neutral electrical distribution system to flow across the equipotential plane generating a dangerous and hazardous voltage to drive the stray current into and through humans and cows and pigs with devastating results.Donald Zipse
 

wirenut1980

Senior Member
Location
Plainfield, IN
I actually disagree with some of what is in that paper. To say only voltage or current is what matters is not correct. True, current is what kills, but I have seen a case where there was 5 amps flowing through bonding conductors. These bonding conductors were bonding grounding systems of power, cable, and phone at an office building with 2 transformers and services. The comm guys were getting a spark when a bonding conductor was lifted. We took several different measurements thinking there was an open neutral somewhere, but everything checked out fine. There was pretty significant neutral current on the power neutral, and the parallel grounding paths were good enough that they were handling part of that neutral current return path.

Anyways, my point of this case study was that we installed a 500 ohm resistor (to simulate a human resistance) in the path, and the current dropped to nothing. The power system neutral was now by far the best path. So, I could touch the ground bar and even put myself in the path and was ok. So, to say that 5 amps of current can kill you with no other explanation...well, it depends. :D There is a more exhaustive explanation and drawing attached.
 

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wirenut1980

Senior Member
Location
Plainfield, IN
Also, the experiment in the paper with the bucket bonded to the equipotential grid, I question that as well. If all was bonded together, how did the current flow? The voltage between the bucket and equipotential plane was conveniently left out.:huh:
 

WIMaster

Senior Member
Location
Wisconsin
Has this guy told lineman that intentionally bond themselves to very high voltage to create an equopotential plane that it doesn't work and that they are all really dead and just think they are alive??

I am pretty sure he is unwilling grasp the entire concept and the fact that it does work. equopotential = equal potential = zero voltage difference hmmmm
 
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