That is what I was thinking I would have to do originally so I'll definitely be posting about the outcomes.
bonding vs grounding question
- Thread starter cptserious
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What is the accuracy of the last paragraph in this article which is below? Pool Bonding 101: Why Handrails, Coping, and Water Could Shock You.
If you are speaking of the possibility of the grid feeding electric back to the pool section.
Here is something to mull over... First off we need to get a general understanding of the physics at play here. One of the fundamentals is, everything has a certain amount of electrical potential. another misunderstood fundamental is that electricity does not seek ground. It seeks it's source. In other words, the electric that is fed to your home wants to get back to the place it came from. In the case of a normal electrical grid this will be the transformer. Now there are some variable that come into play here that may cause some of this power to be in the ground as an alternate path back to the transformer. Also, as we were falsely taught in school, electricity does not take the path of least resistance. It takes all paths. It will primarily take the least resistive path but unless there is a zero ohm path it will be present on all conductors. Now for the one that is hard for everyone to grasp. The earth is not at zero volts. it could be, for example, 1,000 volts (we really don't know what it is)but, since everything else around it is close in voltage and the resistance is high we never feel the differentials when we touch two different objects.
Here is a way it was explained to me several years ago...
Assume you are sitting in a parked car on the side of the road and another car passes you at 60 MPH. We can determine the speed at which that car passes by measuring the speed. We measure 60 MPH in reference to zero (the parked car). This is the same as voltage potential in an electrical outlet. However, is the parked car really at zero MPH. Remember, the car is sitting on the planet earth which is spinning on it's axis roughly 1,000 MPH and hurling thru the universe at some unknown speed. since we only truly know one "zero" reference we can only measure one aspect of the speed. The voltage potentials work the same way.
Lets assume that your pool water is at 1,000,000 volts. You would not want to go near that would you? Now lets assume your deck is at 999,999 volts. If you are standing on the deck, you are at the same voltage as the deck. Now touching the pool water is pretty safe as there is only 1 volt of differential. If we have a way to connect the two with a low resistance path (bonding wire) then the potential will even out thru the wire and since you are a more resistive path you will not feel it.
Is I mentioned earlier, I don't think your voltage differential is coming from the grid as much as I think the pool is sending voltage to it. Either way there would be voltage flow. I really wish you were in Knoxville Tenn as I will be there in a few weeks.
Dan
Thank you Dan! This actually makes perfect sense. Given the fact that when I would disconnect the ground wires from the ground bar in the sub-panel for the pool light and pump I would read no VAC difference on the analog multimeter, I started to wonder if the voltage on the main ground wire coming from the main panel was causing a difference in potential thus using me as a means to get to the grid rather than the grid into the water. This would explain why people are saying the grid because if the ladder were truly bonded properly then the difference should level out between the water and grid through the ladder. I have some ideas for a few more tests.
By the way, interestingly enough, my family and I moved to Maryland, not Knoxville originally, from Knoxville TN. ?
By the way, interestingly enough, my family and I moved to Maryland, not Knoxville originally, from Knoxville TN. ?
Well, did a little more testing this evening and I'm not sure what to make of it other than, as almost everyone has said, the bonding wire. I tested the VAC reading between the water and the ladder and of course, there was no reading on either railing or the concrete between the railings. As I got further out from the ladder and cups, I started to get readings around the 0.2 - 0.4 VAC mark. Tested the water to the shallow end hand railings and it was reading 0.2 - 0.4 VAC just like the concrete around the pool other than at the deep end ladder.
Here is my latest thinking (I do have a call into a pool builder in the area to get them involved because it will require a fix).
The deck is not bonded but the area around the deep end ladder is being "somewhat" protected by the fact that the metal cups and ladder are bonded by the water only which is why the further you get from them the more reading you get.
Now the question is... why didn't we feel this last year? Could it be the generator we had installed after the pool was closed? Or the fact that we had to replace the pool pump (even though it is exactly the same with a little more horsepower)? Or could it be that the new concrete we had poured included rebar when there wasn't any in the original deck which was NOT connected to a bonding wire but was within 5' of the pool edge?
So many questions and not a lot of answers. May very well end up doing Dan's idea of the 1" trench but I'm thinking I'll cut along the edge where the old concrete meets the new concrete and tie in the rebar. Only question with that is whether or not it still needs to be buried 4"-5"?
Here is my latest thinking (I do have a call into a pool builder in the area to get them involved because it will require a fix).
The deck is not bonded but the area around the deep end ladder is being "somewhat" protected by the fact that the metal cups and ladder are bonded by the water only which is why the further you get from them the more reading you get.
Now the question is... why didn't we feel this last year? Could it be the generator we had installed after the pool was closed? Or the fact that we had to replace the pool pump (even though it is exactly the same with a little more horsepower)? Or could it be that the new concrete we had poured included rebar when there wasn't any in the original deck which was NOT connected to a bonding wire but was within 5' of the pool edge?
So many questions and not a lot of answers. May very well end up doing Dan's idea of the 1" trench but I'm thinking I'll cut along the edge where the old concrete meets the new concrete and tie in the rebar. Only question with that is whether or not it still needs to be buried 4"-5"?
Just an update while I'm waiting to get a recommended pool electrician out.
I decided to disconnect my pump and SWCG from the bare copper wire coming out of the ground at the equipment pad just to see what kind of readings I would get from the analog multimeter. I got the exact same readings as before when they were hooked up to the wire. Anybody care to take a guess as to why this would happen? Perhaps that wire is not a bonding wire at all but a ground driven far into the earth.
Secondly, when I opened my Pentair junction box cover, I noticed that there were 3 green wires. 1 went back to the ground bar in the sub-panel, 1 went into the protective cover of what I assume is the wiring connected to the light and another was in the same conduit as the light wiring but was screwed down instead of wrapped around a green ground screw. Would the bonding wire of the pool light come up through the same conduit as the rest of the electrical wiring?
I decided to disconnect my pump and SWCG from the bare copper wire coming out of the ground at the equipment pad just to see what kind of readings I would get from the analog multimeter. I got the exact same readings as before when they were hooked up to the wire. Anybody care to take a guess as to why this would happen? Perhaps that wire is not a bonding wire at all but a ground driven far into the earth.
Secondly, when I opened my Pentair junction box cover, I noticed that there were 3 green wires. 1 went back to the ground bar in the sub-panel, 1 went into the protective cover of what I assume is the wiring connected to the light and another was in the same conduit as the light wiring but was screwed down instead of wrapped around a green ground screw. Would the bonding wire of the pool light come up through the same conduit as the rest of the electrical wiring?
Just an update while I'm waiting to get a recommended pool electrician out.
I decided to disconnect my pump and SWCG from the bare copper wire coming out of the ground at the equipment pad just to see what kind of readings I would get from the analog multimeter. I got the exact same readings as before when they were hooked up to the wire. Anybody care to take a guess as to why this would happen? Perhaps that wire is not a bonding wire at all but a ground driven far into the earth.
Secondly, when I opened my Pentair junction box cover, I noticed that there were 3 green wires. 1 went back to the ground bar in the sub-panel, 1 went into the protective cover of what I assume is the wiring connected to the light and another was in the same conduit as the light wiring but was screwed down instead of wrapped around a green ground screw. Would the bonding wire of the pool light come up through the same conduit as the rest of the electrical wiring?
Sound right. The bonding wire for the light will be in the conduit. Run a jumper from that wire over to one of your ladder cups and see if anything changes.
Dan
I will definitely try this. That extra green wire is stranded versus solid. Will that matter or not as long as it is at least #8 AWG?
I will definitely try this. That extra green wire is stranded versus solid. Will that matter or not as long as it is at least #8 AWG?
heavy gauge solid wire is almost impossible to pull thru small dia conduit that is why it is stranded. Also, the wire itself is mot acting as part of the bonding grid in this case. It is only acting as a jumper to the rest of the grid if it is set up properly. The light niche is acting as a water bond point and the wire should be coming out, connecting to the deck box which should also be connected to the bonding grid. Any wire connection between the two points for a test should be fine as all you are doing is equalizing potentials if they exist.
Dan
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