*Shallow end, being shocked when grabbing railing*

gamerfan2004

Well-known member
Jul 3, 2013
143
Newark, DE
Yesterday you measured 1.7 volts between the screwdriver & railing anchor.
If you have time, repeat that test to confirm & check again after disconnecting the bonding wire at the pump.
Also are both of those readings the same whether or not the pump is running?
I can plan to do this, hopefully, this week depending on my other tasks. The readings previously didn't matter if the pump was running or not.
 

Mike1162

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Jun 13, 2015
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N Tonawanda, NY
Let's alter this test a bit. Place the screwdriver where you can test between all four anchors & the screwdriver without having to move the screwdriver. Get readings from all the anchors with & without the bonding wire attached at the pump. The deep end anchors should also be tested with & without the ladder installed. Edit - Just might as well also test the voltage of the water at the stairs & by the deep end ladder with & without the ladder installed.

Am I correct that you believe the NEV is getting to the pool via the ground to the pool light and/or via the bonding wire?
 
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mas985

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Am I correct that you believe the NEV is getting to the pool via the ground to the pool light and/or via the bonding wire?

NEV by definition, neutral to earth voltage, is on the power company neutral. If you watch the above video, it will explain how NEV is created and how the different points in the power distribution network can have different potential on the same neutral lines. The primary NEV current flow is as follows:

Neighborhood Transformer Neutral <-> House Neutral <-> House Ground <-> Pump <-> Bond <-> Railing <-> Person <-> Water <-> Earth Ground

The two end points are at different potentials so current will flow and no matter where you break this circuit and measure the voltage, there should be a potential difference. In reality, current is taking multiple paths back to the substation. It is the path of lowest resistance that will carry most of the current. However, anywhere where there is a potential difference will also carry current.

If the water near the light is at the same potential as the house ground/neutral, that will force the water near the light to be at the same potential as the bond. However, water has resistance so if there is another point in the pool that is also tied to earth ground, there will still be potential gradients in the water which has been measured. Near the stairs there is a higher potential difference from water to railing than the opposite side of the pool. This is all consistent with the bond being at a higher potential than earth ground.

I believe the stairs are the issue. It is giving the current a path to travel from the water into the local earth ground near the railing. Most likely it is either a leak or a bolt/screw touching both water and earth.
 

Mike1162

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So the answer to my question is yes?

If both the bonding wire at the pump & pool light ground have 5 volts & the bare bonding wire is running through the soil isn't the light ground likely to have the most voltage potential?
 
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mas985

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So the answer to my question is yes?
Sorry, yes. I misread the question. Ground can be interpreted in multiple ways so I like to use the terms "house ground" and "earth ground" to differentiate the two and they will have different potentials.

If both the bonding & pool light ground have 5 volts & the bare bonding wire is running through the soil isn't the light ground likely to have the most voltage potential?
Voltage is relative so it is always measured between two points. So assuming the light is bonded correctly, which is in doubt right now, and the railing is bonded correctly, which was confirmed, then both should be at exactly the same potential and would have close to 0v between those two points. However, if you measure the voltage between the railing and a distant earth point, that should have ~3vac as was measured before. Same with the light, again assuming it is bonded correctly. There was a voltage difference measured between the water near the stairs and the railing. However, there is less of a difference the further away from the railing one gets in the water (i.e. closer to the light) which means the water has a large voltage gradient. Again, this all points to NEV on the bond and the stairs having a connection to earth somewhere.

One solution might be to drive in ground rods around the area close to the stairs and connecting them to the pool bond. This would force the soil near the stairs to be closer to the same potential as the bond and as a consequence, the water closer to the bond potential. That may be far easier to accomplish than trying to find the water earth connection.
 

Mike1162

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Jun 13, 2015
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N Tonawanda, NY
However, there is less of a difference the further away from the railing one gets in the water (i.e. closer to the light) which means the water has a large voltage gradient. Again, this all points to NEV on the bond and the stairs having a connection to earth somewhere.
Thanks for helping me understand all of this. Electricity is no longer as simple as I once thought!

I'm not following why you think the stairs must have a connection to earth. Wouldn't you expect the voltage in the water to decrease the further you measure from the source whether there is or isn't a source to earth?
 
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mas985

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Thanks for helping me understand all of this. Electricity is no longer as simple as I once thought!

I'm not following why you think the stairs must have a connection to earth. Wouldn't you expect the voltage in the water to decrease the further you measure from the source whether there is or isn't a source to earth?
Simply because the water is at a different voltage than the railing. If water were in complete isolation (not electrically connected to anything), then there would be no voltage from water to railing. Current could not flow. This means that the water close to the railing does not have a low resistance connection to the pool bond but has a lower resistant connection to earth so current can flow from the railing to the earth and complete the connection.
 

gamerfan2004

Well-known member
Jul 3, 2013
143
Newark, DE
@Mike1162
While I was working on closing the pool for the winter, I did a few measurements like before with the screwdriver far away from the pool area.

The deep end ladder anchors: 72mV

I removed the bonding wire from the pump and these are the readings:

Shallow end anchors: 140mV
Shallow end water: 65mV
Deep end anchors: 63mV
Water deep end: 63mV
Metal coping: 65mV

I started testing the ground around the shallow end and was hitting 140mV around the area. I then started heading toward my neighbors' house (near my pool) and the voltage was increasing steadily up to 300mV as I got closer to their utility/ground/meter connection. I didn't go any further but I found it to be interesting.
 

Mike1162

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Jun 13, 2015
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N Tonawanda, NY
Do we agree that the NEV is getting to the pool via the bonding wire? Seems ironic that the bonding wire is causing the problem that its suppose to prevent.
 

gamerfan2004

Well-known member
Jul 3, 2013
143
Newark, DE
Do we agree that the NEV is getting to the pool via the bonding wire? Seems ironic that the bonding wire is causing the problem that its suppose to prevent.
De Acuerdo Agree GIF
 

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Mike1162

Silver Supporter
Jun 13, 2015
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N Tonawanda, NY
Here's an 'out there' idea that probably violates every code related to bonding. Put a diode between the pump & bonding wire so the wire becomes a one way street.
 

JamesW

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Mar 2, 2011
27,681
In my opinion, bonding a handrail is probably more dangerous than not bonding, especially if the rail is not touching the water.

If a rail is not bonded, then touching the rail is like touching the concrete.

However, if the rail is bonded, there is a strong path through a human who touches the rail while they are in the water.

In the below video, the person only gets shocked when they touch the handrail.

People assume that the rail was probably not bonded, but I suspect that it was bonded and that provided the path for the electricity to flow.

If the rail was not bonded, the person would probably not have been shocked.


Note: The NEC requires bonding and you should always follow all local and national codes.

Also note that Dr. Sanjay Gupta does not really know what he is talking about regarding electricity or this particular incident.

He is speculating on what is happening and why, but he clearly does not know, and he is really not qualified to be presented as an expert in this case.
 
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JamesW

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Mar 2, 2011
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I suspect that there is a significant source of stray current/voltage in the ground that will be difficult to locate and difficult to eliminate or mitigate to and acceptable degree.

At this point, we do not know exactly what the bonding is or isn't.

There is a lot of speculation with very little definite information.

I honestly do not know if you can get this fixed without finding and eliminating the source of the voltage and current.

Unless you get a qualified electrical engineer who really knows how to track this down, I doubt that you will get it found or fixed.

I know of several people who have this same issue and they have given up on finding the problem and they just live with it.
 

JamesW

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Mar 2, 2011
27,681
@JamesW @mas985

Both of you have concluded that the railing is properly bonded. If the railing seems to be checking out, then is mas985 correct about a potential leak in that area?
I don't remember saying that I think that the rail is, or is not, properly bonded.

At this point, I don't think that we have enough information to make that conclusion.
 

gamerfan2004

Well-known member
Jul 3, 2013
143
Newark, DE
I don't remember saying that I think that the rail is, or is not, properly bonded.

At this point, I don't think that we have enough information to make that conclusion.
Gotcha. The post with the video made it sound like that may have been a "Yes" for the railing being bonding based on the scenario.

I know of several people who have this same issue and they have given up on finding the problem and they just live with it.
Basically, replace both the shallow end railing and deep end ladder with a Saftron product?
 

mas985

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Again, I believe the stray voltage is NEV coming from the power company neutral. This is not an uncommon situation and accounts for the majority of all stray voltage. The bonding is at the same voltage as the house neutral so when someone touches the railing, that has a different voltage than the water near the railing so a shock occurs.

The earth can really only have an excess voltage near the location where it is introduced. This is why NEV is always measured to "distance ground" and this is exactly what the OP measured. The voltage between the house ground and the earth ground increases with distance away from the house ground.

 
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