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Old 07-13-2010, 11:42 PM   #61
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I'm still willing to field test yours stubby, same deal as before.
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Old 07-14-2010, 12:36 AM   #62
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Hi Nap

I made an edit on a more serious note in my previous post. Is the concrete part of the EPBG ? Or has that not been verified?
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Old 07-14-2010, 12:43 AM   #63
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No mine is over on ebay I never dreamed someone was actually making the thing. Anyway it's not really mine I just thought some nut was trying to make 50 bucks over the net. I had no idea that a company was behind it.
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Old 07-14-2010, 01:06 AM   #64
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For those interested I saved this thread over on Holts site some time ago. There is a lot to be learned in this discussion.

http://forums.mikeholt.com/showthread.php?t=126243
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Old 07-14-2010, 08:59 AM   #65
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Quote:
Originally Posted by Stubbie View Post
Hi Nap

I made an edit on a more serious note in my previous post. Is the concrete part of the EPBG ? Or has that not been verified?
na. No idea what is actually bonded or if there is steel in the concrete that should have been bonded.

any ideas on how to successfully bond concrete with no steel reinforcements in it? I know concrete is considered to be conductive hence the Ufer system. Just don't know what would be a practical idea if there is no steel.

and that thread over at Mike's is very informative. While it is a serious matter, I couldn't help but laugh when I read this:

Quote:
You could try and map the non-equipotentialness; get your boots and socks off, grab one meter probe, with the other probe still connected to house ground through the extension lead, wander round the surrounding concrete and grass watching the meter. You may locate where the stray current is being injected... And that may lead to an acceptable fix.
or wetting your pants when the tingle got a bit too strong. Never place yourself in a circuit unless you have all the answers about voltage and current first. Meters are cheaper than a funeral.

Last edited by nap; 07-14-2010 at 09:13 AM.
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Old 07-14-2010, 09:06 AM   #66
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Quote:
Originally Posted by Stubbie View Post
I couldn't help seeing the part about the "non conductive water inlet" yoyizit mentioned, which I wondered what that might be as did nap.
Seems I read 'inline' as 'inlet.'
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Originally Posted by rnemt140 View Post
the inline water bonding system
I thought the OP said people got shocked near the water inlet which implied a localized problem but now I can't find that passage. It might have been in one of the other case histories.

Even with this cite
http://ewh.ieee.org/conf/tdc/IEEE_T&...08_Lambert.pdf
I can't seem to find a 'passing value' for voltage, an acceptable minimum. 1 vac is too high, but 0.3 vac and lower might not be detectible by most people.
The use of #8 wire implies that someone somewhere made an E = IR calculation.

Felt shock intensity also depends on frequency, so with harmonics in the 60 Hz this might also cause a variation in the reported results.

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Old 07-14-2010, 09:40 AM   #67
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Quote:
You could try and map the non-equipotentialness; get your boots and socks off, grab one meter probe, with the other probe still connected to house ground through the extension lead, wander round the surrounding concrete and grass watching the meter. You may locate where the stray current is being injected... And that may lead to an acceptable fix.
Maybe they should try this method that was suggested elsewhere.

Quote:
Ground resistance
Stick DVM probes into ground.
Put on amps scale.
Measure
http://en.wikipedia.org/wiki/Telluric_current
Switch to volts, measure voltage.
Divide V by I to get R.
Done.
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Old 07-14-2010, 11:31 AM   #68
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Quote:
Originally Posted by nap View Post
na. No idea what is actually bonded or if there is steel in the concrete that should have been bonded.

any ideas on how to successfully bond concrete with no steel reinforcements in it? I know concrete is considered to be conductive hence the Ufer system. Just don't know what would be a practical idea if there is no steel.

and that thread over at Mike's is very informative. While it is a serious matter, I couldn't help but laugh when I read this:

or wetting your pants when the tingle got a bit too strong. Never place yourself in a circuit unless you have all the answers about voltage and current first. Meters are cheaper than a funeral.
Yeah hopefully that guy was joking.

I don't have any ideas how you would bond the concrete if it has already been placed. At least no ideas that would be cheaper than tearing it out and starting over.

After quickly reading this thread I gotta believe that a bond doesn't exist with the EPBG and the concrete even if the concrete has the copper grid in it. It seems it has failed or poor installation or doesn't exist at all.

I don't have a great deal of experience finding or troubleshooting pool issues like being discussed here other than trying the things you and others have already suggested. If it is more complicated than that then your going to have to find someone that has experience at the next level.

On another note he did say a neutral blocker did reduce the voltage to .74 volts from 1.7 volts. But that could be that all it did was reduce the voltage drop on the service neutral depending on where they placed the blocker....I think. I say this because you are bonded to the egc at the pump assuming it is not double insulated and no bonding lug. All this gives you a bond with the service grounding and neutral bond at the SE. It seems that a test might be beneficial with that bond broken and a potential between the concrete and water taken. Of course I am also assuming that no potential differences exist between other items of the EPBG.

On that thread over on Holts site it was mentioned by one of the electricians that total elimination of potential differences is sometimes hard to achieve .. you just hope the ones that do are very small and away from the waters edge. So I'm not sure what small is but .74 volts is pretty small...except this is at the water and concrete.

It also seems one might want to take some current readings as Jim mentioned a few posts back. If there is current flowing on the EPBG or the egc of the equipment circuits then your issue gets more dangerous.

Just some quick thoughts.

At this point unless the OP will return with any further details or an update with the solution we are just in a discussion with each other over what ifs.

Still though I really enjoy this subject when it comes to pools with problems like we have here. I think it is a weak area of knowledge with most electricians .. at least it is for me. So a lot to be learned in discussions like this one here.
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Old 07-14-2010, 11:57 AM   #69
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Still though I really enjoy this subject when it comes to pools with problems like we have here. I think it is a weak area of knowledge with most electricians .. at least it is for me. So a lot to be learned in discussions like this one here.
I see it as weak area of understanding not only for electricians but for engineers as well. There are a variety of causes and what (I think) happens is when a solution in one case is found, many think it is the solution in all similar situations. Then, when it doesn't work, they start arguing the original repair was incorrect or simply coincidental. Then all the BS starts getting thrown all over the place.


The facts as I see them are:

there are going to be neutral currents and they have a great deal to do with the POCO. Due to their system's designs, they are not curable. It is an inherent part of their design.

As such, the use of an EQPG is extremely important. As such, the design and implementation of such is critical.

just as why a lineman can go and crawl across 738K lines without being injured due to the system he uses to prevent current flow through his body, the EQPG will prevent current flow because it remove the differences of potential that cause current flow. The current flow is still there in the areas not included in the EQPG but due to the lack of difference of potential, there can be no current flow from any point within the grid to any other point within the grid. That is what makes it safe and is not dependent on the removal of the current flow outside of the grid.

The grid can actually have flow through it as it can have a difference of potential between it and some point in the ground but that flow is irrelevant to what happens within the grid itself and that is what the EQPG deals with.

People have a misconception that voltage is only present in a power line or some other intended conductor. That truth is, voltage is simply a measurement of the difference of the charges, whether they be a positive or negative charge, between two points. You can measure a voltage between just about any two points that are isolated from each other. Nature pretty much causes that. If you take any two points and bond them, it equalizes the charge within what is now one conductor and removes the reason for current flow. While the charge itself is still there, it just will not flow until there is a connection with a point with a different level of charge.

and that connection and subsequent equalization is the job of the EQPG. It is only when you are the connection between the grid and some other conductor that has a different charge will there be current flow which we recognize as being shocked.
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Old 07-14-2010, 12:44 PM   #70
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I can't really find any fault with what your saying as it does seem that potoential differences would be removed if the EPBG is constructed with the necessary care.

What I do have a problem with is just how to you bring all the water at every point in the pool to the exact same potential with the EPBG?. The chemicals make the water quite conductive but it doesn't seem as simple as metal to metal bonds. It seems to me it would be much like earth (dirt) where the potential floats from point to point. In other words would the potential necessarily be the same getting out of the pool on a metal ladder that is bonded to the EPBG vs. getting out of the water by just lifting yourself up on the concrete on the other side of the pool .. assuming wet concrete?

A metal ladder is going to bond the water if the EPBG is correct but there are a lot of pools where that bonding doesn't exist unless you install something that bonds the water with the EPBG. So my thought is a lot of non-bonded water is not shocking people even if the concrete walkway has the bond with the EPBG. It would seem that these pools would inherit a potential difference due to non-bonded water yet they do not shock you.
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Old 07-14-2010, 01:00 PM   #71
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As long as we're on the subject -
With bulk resistivities contact surface area is important so if a swimmer with 4 sq. in. hand surface and 8 sq. in. footprint area gets a shock and the current flows from hand to foot, for repeatable results the body simulator should have two conductive meshes with these areas, with a resistor in between.
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Old 07-14-2010, 02:54 PM   #72
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It would seem that these pools would inherit a potential difference due to non-bonded water yet they do not shock you.
Not all pools are subject to the same charges via the ground. Some pools would cause no shocks whatsoever if there was no EQBG let alone an imperfect one. Remember the code generally doesn't required a GEC in a house if it is probable that there will be a situation that it is beneficial or that a grounding electrode system is required only on houses that are likely to experience surges; they are required on all houses regardless of the propensity of that house to be subject to the problems the grounding systems are installed to safeguard against.


Pools are the same. Not all pools will be subjected to ground currents which result in shocks but since some do and it has found to be beneficial, all pools are required to have the EQBG.

in other words; better safe than sorry.
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Old 07-14-2010, 11:24 PM   #73
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Sorry so long getting back to your response NAP. Had several issues that took most the afternoon and evening.

Anyway I do agree with your analysis that there are so many variables with ground voltage gradients that an EQBG must be installed in the event a pool not subject to ground voltages/currents suddenly becomes subjected to one.

Without it you have no way to protect people from a voltage gradient that appears from any number of faults. You also have no way to correct any potential difference to the concrete if it doesn't have the bonding grid.

In the case of this thread and the op's original problem it seems that the solution is verifying everything is bonded to the EQBG. I would suspect the concrete doesn't have any grid to bond to or was flawed design when installed or the bond has failed.

I wish he would return with more details after reading our responses. It would be great to determine what fixes his problem.
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Old 07-14-2010, 11:53 PM   #74
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I think the OP might be overwhelmed with the discussion.

sounds like OP got a raw deal from the installing electrician as well. If it were me, I would call a reputable electrical company to determine what it would take to correct all of the problems and go after the installer.

Then, when they have a proper installation, they can deal with any problems remaining.
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Old 07-15-2010, 07:10 AM   #75
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A question that must not be overlooked.

If the concrete does not have rebar in it, is there any way to solve the problem without destroying the pool?

I would consider the lack of an equipotential bonding grid to be an omission as opposed to a defect. Other than the cost of copper, burying wires in the ground at the perimeter of the pool is not that hard.
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