Feeling a small shock on one side of pool deck / possible bonding issue?

[wc!]

This is my first post here on TFP, so I apologize if this is in the wrong place.

We just had an in-ground pool installed and we've been swimming in it for about 3 weeks now. It's an 18x36, vinyl lined over vermiculite, polymer walled, salt water pool with a SWG, LED lights, a heat pump, and surrounded on all sides by a concrete deck (with a rebar grid). Everything was going fine until about 2 days ago when one of the kids said that the pool shocked them. I wasn't home, but my wife was in the pool at the time so she got out and reenacted the process. She placed one foot on a wet spot on the concrete and dipped her hand in the water and sure enough, she felt it too. It was small, but it was there. She got the kids out, called me, and I came home and tested it myself. When I tried to recreate it to feel the shock, I felt nothing. I even gave myself a paper cut and retried it to see if that helped, and nothing. My wife stood beside me and did the exact same thing that I was doing and she could feel it again and again and again. Since I couldn't feel it, I grabbed my multi meter to see if I could see anything strange and when I put one led in the water and one on the wet deck, I saw 0.15 - 0.33 volts on that side of the pool. When I tested the other 3 sides, the meter only showed 0.004 - 0.006 (small enough to be considered nothing). It's small voltage on the one side, but something is there. After I saw it, I started back-tracking from the pool sub-panel back to the main breaker at the house. One by one I flipped the breakers off, rechecking the voltage each time. In the end, I cut power to the entire house by the main breaker and still saw the the voltage. I called the electrician back out and he went over everything from the pool to house and said everything was grounded and connected properly. He reached out to the power company and is having them check their end. Our guess is that there is stray voltage from the power company coming in on the neutral line, but we're waiting for the power company to come out and take a look at it.

The power company is looking into the stray voltage and they should be able to take care of it (I hope), but it doesn't solve the second problem of me being able to feel they stray voltage when we touch the water and the deck. I went back to the pool guy and we talked about bonding and he said everything was bonded correctly and it was inspected by a county inspector and passed. I was lucky enough to see my pool built from ground breaking until the final chemicals were added, so there are things that I do know happened. For instance, I know that there was a rebar grid laid out all around the pool prior to the concrete being poured. I know that there was a copper wire attached to the hand rail well, then run across the rebar, then connected to the ladder well, then run across more rebar, then to the anchors for the diving board, then finally extending out of the concreted pad (it's now connected to the heat pump). I also know that there was an inspector at the house and that bonding is part of the inspection process, and everything was in fact "approved" by him. The coincidental part of all of this, is that the bonding wire and it's connection locations are all on the 3 sides that are showing no voltage so I'm wondering now if the wire either A) should have been connected to the other side of the deck too, or B) that there is a break in the rebar connection on that side of the deck making it it's own separate (and now unbonded) grid.

My questions are:

1. Is the voltage I'm seeing on the one side of the pool within normal earth/ground levels and I'm just making something out of nothing?

2. Should the copper bonding wire have been across and connected to all 4 sides of the pools concrete pad rebar, or should have just connecting the wire to any point on any of the rebar worked for proper bonding as long as all of the rebar was connected to each other (by touching or ties)?

3. If for some reason there is a break in the rebar on that side, could I rebond that one side by chipping away a small section of the concrete until the rebar is exposed, then running a new copper wire from where the original one exits the concrete and attaching it to the newly exposed rebar? Or, does the wire in fact have to be run across all of the rebar on that side so connecting it to one point is pointless?

Sorry to be so lengthy in my first post here, but I wanted to give as much info as possible. Any input would be greatly appreciated!

Thanks!

 

[danpik]

This is my first post here on TFP, so I apologize if this is in the wrong place.


My questions are:

1. Is the voltage I'm seeing on the one side of the pool within normal earth/ground levels and I'm just making something out of nothing?

This is not really an easy question to answer easily. There is always a certain amount of voltage potential in everything. Potential is what makes electricity work. Take a flashlite battery for example: There are two voltage potentials. One at each end. As we all know the positive end is at 1.5 volts of potential to the negative end. With that, any connection between the two will cause a voltage to flow on that connection. The same thing is happening between the water of your pool and the deck. Each one of them is at a certain voltage potential as you measured. Since in the universe we do not have a true "0" volt reference, we use the earth as "0". Unfortunately things around it such as pool water may be at a slightly higher or lower voltage potential than the earth. This is why the bonding grid is so important. Without it, anything else that comes between the water and the deck becomes the conductor (such as your wife and kids)

2. Should the copper bonding wire have been across and connected to all 4 sides of the pools concrete pad rebar, or should have just connecting the wire to any point on any of the rebar worked for proper bonding as long as all of the rebar was connected to each other (by touching or ties)?

It sounds to me like the rebar connections themselves are not real good. Remember, two round items laying across each other do not have a lot of contact surface. Realistically, the rebar should have all been wire tied tightly and the copper wire split-bolt connected to the rebar instead of just laying across it. The copper wire also should have been ran completely around the pool with at least 4 connection points to the shell/deck at equal points around the pool. It is possible that the rebar grid is not properly connected together to complete the grid or it could be coated rebar that will be useless as a grid.

3. If for some reason there is a break in the rebar on that side, could I rebond that one side by chipping away a small section of the concrete until the rebar is exposed, then running a new copper wire from where the original one exits the concrete and attaching it to the newly exposed rebar? Or, does the wire in fact have to be run across all of the rebar on that side so connecting it to one point is pointless?
Thanks!

I would try to gain access to the rebar as a first attempt to fix this problem. If not, I would consider having the deck saw cut to a depth of 1"-2" and grout in a copper wire that I would then connect to the rest of the bonding grid.

Is there a water bond device installed in this pool too?

 

[borjis]

is the SWG, LED Lights and pump motor connected to the bond wire as well?

if not, that could be it.

 

[wc!]

Thanks for the responses!

The copper wire also should have been ran completely around the pool with at least 4 connection points to the shell/deck at equal points around the pool. It is possible that the rebar grid is not properly connected together to complete the grid or it could be coated rebar that will be useless as a grid.

I know that the wire was connected to the rebar by what appeared to be a copper screw clamp of some kind. The rebar was plain exposed metal and was twist tied together at the over lapping points with some sort of wire. Unfortunately, I also know that the bonding wire was NOT run completely around the grid. The side showing the voltage has no wire. There were at least 4 connection points, but they were not spaced evenly and they are all on the 3 sides that show no voltage. I think that the rebar overlaps and connections just aren't enough without the help of the wire.

Is there a water bond device installed in this pool too?

It looks like the ladder is used for this. The ladder well is attached to the bonding wire and rebar. Since the ladder touches the ladder well and the water, I would think that would cover it.

is the SWG, LED Lights and pump motor connected to the bond wire as well?

The LED lights and pump motor, yes. I'll have to look at the SWG, but off the top of my head, I would say no (you mean the inline cell, right?). If I recall, the cell is enclosed in plastic so I'm not sure how to bond it. I'll take a look at it when I get home and get back to you.

Thanks again!

 

[danpik]

It is entirely possible that as time has gone by, the rebar has rested sufficiently to insulate the steel from the concrete. This is why there should be a copper wire surrounding the pool

 

[wc!]

The SWG control unit was not bonded. There's a bonding lug on the bottom, but nothing was connected to it. I ran another #8 wire from that bonding lug back to the original bonding wire so that it's now bonded, but I still saw the voltage. It needed to be done per the manual, regardless.

I think I found the problem though, but I wanted to get another opinion. When I follow the bonding wire out of the concrete pad, I see that it connects to the heat pump, then to the bonding lug on the pump, but then it runs inside of the electrical panel. Unless there's a specific bonding lug inside of the electrical panel, which wouldn't make sense for it to be on the inside, then I think the electrician connected the bonding grid to the electrical ground or neutral and I think that's where the voltage is coming from. My understanding is that the bonding grid is NOT supposed to be grounded or connected to anything in the electrical system. I'm thinking that if I disconnect that bonding wire from whatever it's connected to inside of the panel, then everything should be as it's supposed to be (except for the separate issue of having voltage on my neutral, which the power co is still getting around to checking into). What do you think? I just don' know of any reason that the bonding wire should be running into the electrical panel at all, unless its just floating loose and in there just to hide it.

 

[ssgumby]

The SWG control unit was not bonded. There's a bonding lug on the bottom, but nothing was connected to it. I ran another #8 wire from that bonding lug back to the original bonding wire so that it's now bonded, but I still saw the voltage. It needed to be done per the manual, regardless.

I think I found the problem though, but I wanted to get another opinion. When I follow the bonding wire out of the concrete pad, I see that it connects to the heat pump, then to the bonding lug on the pump, but then it runs inside of the electrical panel. Unless there's a specific bonding lug inside of the electrical panel, which wouldn't make sense for it to be on the inside, then I think the electrician connected the bonding grid to the electrical ground or neutral and I think that's where the voltage is coming from. My understanding is that the bonding grid is NOT supposed to be grounded or connected to anything in the electrical system. I'm thinking that if I disconnect that bonding wire from whatever it's connected to inside of the panel, then everything should be as it's supposed to be (except for the separate issue of having voltage on my neutral, which the power co is still getting around to checking into). What do you think? I just don' know of any reason that the bonding wire should be running into the electrical panel at all, unless its just floating loose and in there just to hide it.

the bonding wire should not be connected to ground inside the panel. It should be connected somewhere on the outside with a copper lug, but not tied to ground in the panel.

 

[danpik]

How are you determining there is "voltage" on the neutral line? The neutral line is at 0 volts referenced to the hot lines. There is almost no way (other than expensive testing equipment) to check for line voltage on a neutral wire.

As for a POCO problem, It may be possible. I have heard about voltage leaks on underground lines so there is always a possibility.
I dug back to an earlier post I had and copied this as I did not want to rewrite it...

Several years ago I had to fix a bonding problem on a pool. The owner was getting some pretty severe shocks and was sure it was a problem with something on the POCO lines. I fixed the bonding grid around the pool and eliminated the shocking problem. He was happy but still was convinced it was something on the POCO side. Fast forward about 2 years and we had a large area wide power outage that lasted several hours and covered a large portion of the northeast. With nothing to do I decided to test a theory. I went to his house, unhooked the bonding grid from the water and tested again. With an area wide power outage there should have been no "stray" voltage in the area. When I put one meter probe in the ground and the other in the water I measure a voltage differential of almost 3 volts.

Now even if there was a stray voltage from a power co fault, the properly installed bonding grid would have eliminated the problem by bringing everything into the same voltage potential.

I also wrote this a while back...

Bonding and grounding are two often misunderstood concepts. To start, we will look at grounding first. In the 120 volt electrical supply system for your pool pump there are 3 wires. Hot, Neutral, and ground. The hot and Neutral serve to move power from the source and back to the source so the pump can run. The ground wire in this system serves only as a non resistive conductive path back to source should something happen internally in the pump. For example, if, for some reason, the hot wire came in contact with the motor housing, the housing could become energized. Without the ground present, the housing could sit there waiting to shock any unsuspecting person or animal who happened to touch it. You would be the conductor to ground. Ground being the ground you are standing on. Now, because the resistive properties of the ground you are standing on are too high for the current to short circuit back to the source, it would most likely not trip the overcurrent protection (fuse, breaker). A couple of times here I have referred to "source". This is the power company transformer on the pole out at the street. The hot and neutral connections are both on this transformer and the returning current wants to get back to what is called the center tap on the transformer either via the grounding system or the neutral system. If there is a ground wire present in the circuit, the hot wire coming in contact with the motor housing would immediately trip the overcurrent protection as there would be a dead short in the system.

Bonding. The really miss-understood concept.
Have you ever experienced a static shock?...You know, you shuffle your feet across a carpet in the dry season and touch a metal doorknob. If you were bonded to that doorknob when you shuffled across the floor you would not have felt it when you touched it. Everything in the universe has what is referred to as electrical potential. Humans have a certain potential, a piece of steel has its own potential, water its own, etc, etc, etc. Most times this potential is not different enough to feel it. When you shuffle your feet on the carpet though your potential changes from that of the doorknob. When you get close enough to the doorknob though both you and the doorknob want to get to the same potential. when that happens, a spark jumps the gap and evens out the potential. Fortunately there is little amperage behind it so there is no chance of getting electrocuted. Now, lets look at your pool. your pool pump is grounded back to the source thru the ground wire. But, it still is at some level of potential. Your pool water is at some other level of potential, your heater at its own level, heck, the ground you are standing on is at some level of potential. This means that all of the items in the vicinity have some varying degree of electrical potential. Under most circumstances these potentials are so close to each other that you never feel any kind of shock. however, every once in a while something happens to change the potential of one of the items. It could be a stray voltage induced from an underground electrical service, It could be a slight resistive leakage of current in your pumping system. What ever it is there is a potential difference. Now imagine you are getting out of the pool and as you touch the metal side of the pool you get the shock of your life. Hopefully not enough to kill you but a good shot none-the-less. Guess what? You just became the bonding conductor in the system. Had all of the components in the system been bonded together by the #8 bonding wire you never would have felt it. The wire is a non-resistive path between all of the components and since electricity is lazy, it will take the least resistive path. (actually, it will take all available paths. It just likes the least resistive more) This bonding system will also protect you if you were standing on the ground and decided to touch the water to see how warm it is. If the bond is in place there would be no potential difference between the water and the ground even if there were a stray current floating around.

Hopefully this helps clear some of this up

 

[wc!]

How are you determining there is "voltage" on the neutral line? The neutral line is at 0 volts referenced to the hot lines. There is almost no way (other than expensive testing equipment) to check for line voltage on a neutral wire.

It's really just a best guess based on my limited knowledge. When I back tracked from my pool sub panel to the main house panel and ultimately flipped the main on/off breaker to the house, I still saw the voltage. My understanding is that when you turn this main breaker off, the neutral is still active back to the poco so I just guessed that it was where the voltage is coming from. It could be coming from the earth, but the neutral just seemed more logical. My electrician came to the same conclusion, so we're waiting for the poco's input now. I'm no expert, so please correct me if my thinking is off.

You seem to know a lot about this subject. What is your take on the bonding wire running back inside of the electrical panel? Not knowing exactly where it's connected (yet), is there any reason for this?

 

[danpik]

It's really just a best guess based on my limited knowledge. When I back tracked from my pool sub panel to the main house panel and ultimately flipped the main on/off breaker to the house, I still saw the voltage.

This was the voltage measured at the pool (water to earth)? Or did you meadure voltage on the neutral somehow?

My understanding is that when you turn this main breaker off, the neutral is still active back to the poco so I just guessed that it was where the voltage is coming from.

Yes, the neutral or "grounded conductor" is not switched. This is tied back to the POCO transformer and ultimately to the grid back to the generating source.

It could be coming from the earth, but the neutral just seemed more logical. My electrician came to the same conclusion, so we're waiting for the poco's input now. I'm no expert, so please correct me if my thinking is off.

you will/should see a small measurable difference in the neutral to earth connection. Remember, the ground in your service is different from the earth. The only place it will be similar in potential is near any ground rods. I can drive a ground rod and connect one lead from a meter to it. I can then go, say 25' away and drive another rod and connect the other lead from a meter to it. It will not be big, but I will be able to measure a voltage differential between the two.

You seem to know a lot about this subject. What is your take on the bonding wire running back inside of the electrical panel? Not knowing exactly where it's connected (yet), is there any reason for this?

There should be no bonding wire running to the sub panel. It is most likely connected to the ground bar inside the box or possibly to an add-on lug. Either way disconnecting it won't hurt anything. It was mistakenly ran that way as back in the day it was assumed everything would be safe at what ever potential the neutral /ground wire is at. In truth, the only time a ground wire is at 0 volts potential is when it is measure against the transformer output. In this case it is used as a 0 volt reference source. In reality, it could be at 1,000,000 volts and the hot side would be 1,000120 volts. In this scenario, everything else around it would be at 1,000,000 volts+ - 1 or two volts. Think Bird On A Wire. The bird is at the same potential as the wire so he feels no electricity. If he were to touch something else at the same time as the wire he would be the bonding conductor in the circuit

 

[wc!]

This was the voltage measured at the pool (water to earth)? Or did you meadure voltage on the neutral somehow?

I measured it at the pool, from the water to concrete pad.

There should be no bonding wire running to the sub panel. It is most likely connected to the ground bar inside the box or possibly to an add-on lug. Either way disconnecting it won't hurt anything. It was mistakenly ran that way as back in the day it was assumed everything would be safe at what ever potential the neutral /ground wire is at. In truth, the only time a ground wire is at 0 volts potential is when it is measure against the transformer output. In this case it is used as a 0 volt reference source. In reality, it could be at 1,000,000 volts and the hot side would be 1,000120 volts. In this scenario, everything else around it would be at 1,000,000 volts+ - 1 or two volts. Think Bird On A Wire. The bird is at the same potential as the wire so he feels no electricity. If he were to touch something else at the same time as the wire he would be the bonding conductor in the circuit

That's what I was thinking as well (after a lot of research). I'll ask my electrician first to make sure he's not doing something wonky inside the sub panel, but I'll open it up and remove the bonding wire this weekend. I'll post back what happens, but my guess is that once I disconnect it, there will be no more voltage reading from the pool to the concrete. If I get in the sub panel and the bonding wire is just floating, or it's not connected to the ground bar, I'll be beck to scratching my head and waiting for the poco.

Thanks for all of the help and information!

 

[70runner]

Removing the bonding wire from the subpanel will not isolate the equipotential grid from service ground. Electrically, the bonding grid will likely still be grounded via a pump/heater bonding lug and EGC.

The bonding discussion above is a good one, however, to mitigate the occurrence of variable potential levels among pool components the current NEC bonding protocol essentially requires pools be energized with whatever potential difference exists between the utility neutral and earth during normal conditions. Safer?...perhaps.

 

[danpik]

Removing the bonding wire from the subpanel will not isolate the equipotential grid from service ground. Electrically, the bonding grid will likely still be grounded via a pump/heater bonding lug and EGC.

True, this is not really a problem though. This is one of the minor discrepancies with the NEC protocol that I feel needs to be addressed

The bonding discussion above is a good one, however, to mitigate the occurrence of variable potential levels among pool components the current NEC bonding protocol essentially requires pools be energized with whatever potential difference exists between the utility neutral and earth during normal conditions. Safer?...perhaps.

I am not sure I can agree with this statement completely. We are not trying to energize anything. Bonding simply brings all voltage potentials into the same level. lets assume for a moment that the pool water is at 0 volts. In a vinyl lined pool, the steel frame is isolated so it will not be at the same voltage potential as the water. lets then assume that the water being at 0, the pool frame is at +3 volts, the ground(dirt) around the pool is at -2 volts and the pump motor is at -3 volts. A meter connected between any two of these items will show some sort of voltage reading. If you touch any two of them you will be a conductor between them and a voltage transfer will occur. If we connect a bonding wire between all of them then the voltage potentials will even out. This eliminates all of the step/touch potentials that was causing the shocks. Now, if the system neutral was connected either intentionally of inadvertently thru the EGC no change would occur other than the system neutral would be at the same potential. All we really have done is equalize the voltage potentials.

 

[wc!]

As an update to this, I did not disconnect the bond wire from the panel this weekend. I did, however, open the panel and confirm that the bonding wire is in fact connected to the neutral bar. I also confirmed with the PB that this was not the norm in his builds (normally uses a different electrical contractor) and in his opinion, the bond wire should have just ended at the SWG. I contacted the electrician and got an ear full about how my meter was cheap, he knew what he was doing, hes been doing it that way for years, he knew the rules, if I wanted to take over it's all on me, etc, etc, etc.

At this point, I'm leaving everything as is in case something else fails inspection so he can't say that it was something I did. I will meet the PB, the electrician, and the inspector at my house for the final inspection and raise the question at that point. I'll post back and let everyone know what happens. Thanks again!

 

[danpik]

I would stick the shocking problem squarely on the shoulders of the pool builder. It is up to him to deliver a safe pool to you. It should be of no concern to you who his electrician is, only that he (PB) will ensure that the job is done correctly and passes inspections. I would let him deal with the electrician and the inspector. It would be good if you were there to ensure the conversation goes smoothly in your favor

 

[diverminh]

I ordered my panels from Solar Pool Heating . The panels turned out to be Techno-Solis panels. The reason why I ordered from Solar Sun Pacific instead of eBay was because they panel seemed to weigh more (thicker material?) than the eBay panels. So far I have been very happy. The only complaint I have about Techno-Solis panel is that it did not come with enough screws. I had to go to my local hardware store to pick up some more screws at an extra cost of $40.