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Old 07-20-2010, 01:15 AM   #91
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another note


we do have a battery back up for our sump pump but we have disconnected it as well and still have the voltage present.

Could a satelite dish carry a charge?
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Old 07-20-2010, 06:29 AM   #92
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OK, I have read a lot of the comments here. I am not an expert but from what a gather here is my 2 cents. We all know shared neutrals are a bad thing and they have been removed from the code pretty much everywhere but one place: from the POCO transformer to the service entrance. The neutral is grounded at the transformer and grounded at the service. We know the unbalanced current flows on that neutral which means some small amount of current flows along the ground as well. The OP said that the POCO "box" also feeds a community park. If that means the park comes off the same transformer there will be ground currents from its service back to the transformer as well. I would be curious to know if the pool sits between any of those sources.

Likely the house ground at the service is at a different potential than the ground at the pool. Does the pool have a sub panel? I would be curious to see what happens if the breaker to the sub is turned off and all connection wires are removed at the sub: both hots, neutral and ground. Will shocks still occur?

As for a solution, we have to get everything at the same potential which means grounding the water, ladder handles and concrete in an equipotential grid. The OP said the concrete has rebar but likely none of it is accessible to attach ground wires to. Someone posted that there is a stick-on product that can be used to ground concrete. If such a product can be found you might want to try it. It is a lot cheaper than breaking up parts of the concrete to get to the rebar.
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Old 07-20-2010, 06:35 AM   #93
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First of all, the voltage readings you are taking are almost meaningless. Yes, there is something there, but sticking a probe in the water is not an accurate test.

PLEASE DO NOT use this pool until you at least have ALL the electrical violations fixed.
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Old 07-20-2010, 06:41 AM   #94
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Quote:
Originally Posted by SleepyDog View Post
We all know shared neutrals are a bad thing and they have been removed from the code pretty much everywhere but one place: from the POCO transformer to the service entrance.
HUH???
A) They are NOT a "bad" thing at all if wired properly. If (collective)you don't know how to wire properly and safely you should not touch it.
B) They have NOT been removed from any code I know of.
Where are you getting your information from?
Please do not make statements based on scare tactics and hearsay.



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Originally Posted by SleepyDog View Post
The neutral is grounded at the transformer and grounded at the service. We know the unbalanced current flows on that neutral which means some small amount of current flows along the ground as well.
Again, HUH??? Current pretty much ALWAYS flows on the neutral. How do you think 120v loads work?
Current flows on the ground as well??? It should not. If it does there is a problem that should be fixed. Current on ANY ground is NOT normal and IS a problem.
Grounds are meant to carry fault current ONLY.
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Old 07-20-2010, 08:11 AM   #95
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If the satellite dish is plugged in somewhere and had a coax or HDMI or other feed to the pool area, then yes it could carry a charge.

I think the next step is to bond the rebar to a common "grounding wire" (if not already) at two places on opposite sides or corners of the pool. If that isn't good enough then add two more bond places for a total of four more or less equally spaced. This will of course require digging perhaps a 3x3 inch hole into the concrete at each chosen location and patching.

I am not sure what kind of wire to attach to the rebar. Experts may recommend copper despite the problems that normally accompany dissimilar metals and moisture. If something else such as a stainless steel wire is suggested instead, then at least the dissimilar metal boundary (a splice to copper wire after just a foot or two of stainless teel) will be out on the surface where it could be redone periodically if needed.

If you still have problems then I suggest the copper wires buried in the soil around the perimeter. With the rebar bonded, you could start with just two perimeter wires a foot apart (with a copper wire "ladder rung" between them every 12 inches as described earlier.)

You will have copper wires on the surface here and there to bond everything including handles together, These wires will need to be glued down with epoxy or something so they don't come loose and get tripped over.

Quote:
... (shared neutrals) have not been removed from any code ...
Probably confused with the National Electric Code's being modified recently to no longer allow an outbuilding to be fed with hot(s) and neutral and no grounding conductor where the outbuilding had rods for grounding electrodes. Where the neutral was not to be shared with ground before or after the change.
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Last edited by AllanJ; 07-22-2010 at 07:00 AM.
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Old 07-21-2010, 06:40 AM   #96
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I don't want to sidetrack this discussion since it does not help the OP but shared neutrals used to be allowed for dryers, stoves etc. Heck, back in the 1970's era code there was an exception that allowed what today we call SEU cable to be used for a stove. The neutral to an outbuilding on a 3 wire connection that used to be allowed is not a shared neutral since the neutral and ground are kept separate at the sub. There was a great article on this in either this or another thread on this type of problem from the IEEE.

I agree with everyone that that concrete has to be bonded to the home grounding system which is at the ground potential back at the service. The ground at the pool is at a slightly different potential which is causing the shocks. The problem is that I know of know easy way to do this without breaking up concrete. If anyone has a way to do that, it would certainly help the OP.
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Old 07-21-2010, 09:13 AM   #97
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Quote:
Open pool for summer of 2008 (Shock noted unable to find source shock from pool water to concrete and pool water to handles)
From your previous post which gave us very good details it appears that you have an external fault introducing a voltage gradient to the pool area. What I note is that a neutral blocker at the transformer(?) reduced the voltage by around 1 volt assuming this test was done properly. So maybe a neutral earth problem (NEV).

The bonding of pool water was required in the 2008 code cycle . And it was required mainly because of pools that have insulated walls or liners (like vinyl) and non metallic ladders. This increased the possibility for a voltage potential to exist with the water and the concrete deck.

Note also that typically when you had concrete pool walls with reinforcement rebar and metal ladders that were bonded to the EPBG potential differences between the deck, metallic ladders and pool water rarely existed with a properly designed EPBG. Because the water was properly bonded by the metal ladder and the EPBG in the the pool walls.

So I have a few questions.

You state that a shock occurs when you touch the handles of a ladder. This implies you have a metal ladder (s). So first question ? Are the foot rungs between the handles plastic?
I ask this because it is possible that only one handle bar was bonded to the EPBG... or that none were if the rungs are metal. A simple test to see if you might be able to eliminate the shock with the ladder would be to connect both handles with a copper wire like a #10 or #8 awg and then run to an exposed bonding conductor for the EPBG and connect it.

My second question is are you also getting shocked just getting out of the pool without the use of a metal ladder or any other metal contact point? In other words can you reach out of the pool and as a result get the concrete wet and then receive a shock when you touch the concrete.

Lastly and I go back to what Speedy said you need to get the violations corrected first ...like the uf-b.

Here is a comprehensive graphic aided overview of what your pool install should entail. This should help see what NAP and Speedy are talking about. If you notice you will see the 2 types of acceptable metal grid that needs to be around the pool ( rebar or manmade copper grid). Your metal pool ladders and metal around the pool are connected to this grid work which is then connected to all the other required bonding items. All of these connected together make up your equipotential bonding plane and if done properly you should not receive any shocks around your pool regardless of voltage gradients from electrical faults or just the always present neutral current in the earth.

http://www.ct.gov/dps/lib/dps/office...pools_2005.pdf
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Old 07-21-2010, 09:46 AM   #98
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Quote:
Originally Posted by SleepyDog View Post
I don't want to sidetrack this discussion since it does not help the OP but shared neutrals used to be allowed for dryers, stoves etc. Heck, back in the 1970's era code there was an exception that allowed what today we call SEU cable to be used for a stove. The neutral to an outbuilding on a 3 wire connection that used to be allowed is not a shared neutral since the neutral and ground are kept separate at the sub. .
this is not what a shared neutral is. A shared neutral is where you have more than one circuit sharing a neutral. In other words; a multiwire branch circuit.

you are speaking more of what I would consider to be a combined neutral/EGC. I don't know if there is any industry used term for the system you are speaking of but it is not a shared neutral.
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Old 07-21-2010, 10:01 AM   #99
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I know this topics has been beaten pretty well and i am no electricion. Maybe this has been proposed already but what would be the negative of putting a grounding rod in the ground and running a wire from it to the pool to see if the voltage drops?
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Old 07-21-2010, 11:58 AM   #100
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I know this topics has been beaten pretty well and i am no electricion. Maybe this has been proposed already but what would be the negative of putting a grounding rod in the ground and running a wire from it to the pool to see if the voltage drops?
there would be no harm is doing it but based on the suggestion, you apparently do not understand the purpose of the equipotential bonding grid (EPBG). The idea of such a grid is to attempt to bring all conductors in the area to the same potential. That means all conductors must be bonded together with a low resistance connection. Ground (both in the literal sense and the electrical sense) is not actually a concern in such a situation unless the ground (literal sense) is within a distance where a person could contact it and some conductor involved in the EPBG.

in the simplest sense;

a shock is caused when there is a difference of potential (voltage) between two points and a conductor (wet swimmer) touches those two points allowing current to flow in an attempt to equalize the electrical charge between the two points.

So, to remove that difference in potential, you bond the two points together so the charges are already equal before the swimmer touches them.

If you can bond all points within the concerned area, there will be no difference of potential between any two points within the bonded area.

Now, how they relate to some area outside of the bonded area is irrelevant (for what we are doing here) . It is only the area within the bonded area you are trying to bring to a 0 potential to any other point within the grid. Regardless of what the potential might be between any point in the bonded area and any other point outside the area is, as long as all points within the bonded area to all other points within the bonded area are at 0 potential, there can be no shock when dealing with 2 points within the bonded area.
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Old 07-21-2010, 12:18 PM   #101
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Well said Nap!
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Old 07-21-2010, 06:06 PM   #102
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i'll bow down now... lol
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Old 07-21-2010, 06:50 PM   #103
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Quote:
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i'll bow down now... lol
no need.

Ya see, you say this:

Quote:
i am no electricion.
I say; this is what I do for a living. I would hope I can bring more to the table than an admitted non-electrician.
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Old 07-21-2010, 07:47 PM   #104
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I still say Bonding,Not Grounding!
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Old 07-21-2010, 07:56 PM   #105
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Quote:
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I still say Bonding,Not Grounding!
Um, ya. That is what an equipotential bonding grid is all about.
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