Inground Pool Bonding Mystery

[ptonsparky]

A high impedance meter will be showing voltage difference to about anything. You do have an issue where your spouse and children can feel it. IDK if the other tests are giving us much.

 

[Fred B]

All readings with ground rod are to a ground rod outside of the bond loop. In some instances I attached the bond loop to it to see if it changed anything.

Really until you are able to validate which components of the EP bonding (Equipotential bonding) that are not linked, the reading to remote earth are not useful overall. You normally will have for a variety of reasons as previously mentioned for voltage differences. Thus the requirement for EP bonding.

Water to ground rod outside of and not attached to bond loop - 0 VAC / 0 VDC

This could be a failed reading, poor connections. A reading like this is what you want to see between components of the EB Bonding, but not necessarily from a component to remote earth.

Remote Earth test has limited help overall as the EP Bonding is designed (or should be) to bring all related components to the same potential (Bird on a wire) to prevent shock regardless of the voltages to remote earth are. EP Bonding done correctly, you could have 120V introduced into the pool and not receive a shock from any contact within the pool bonding area between components of the EP Bonding. The reason for the shock you are reporting is a difference of potential between the components.

Your multiple DC readings between components is indicative of galvanic response from dissimilar metals used in the pool structure and being salt water pool this effect can be enhanced. (This is equivalent to creating a battery with the pool structure.) Look for components showing excessive corrosion or even blackened components. Some component can even be totally disintegrated. Shell of Aluminum or steel and water bond of brass or copper will create such effect. But your use of the cheap Southwire meter is not a real test as the readings are easily negated by the range of +- tolerance of the meter.

Water to coping with bonding attached to ground rod at sub panel - 1.8 VAC and 1.03 VDC

This is the only reading that really has a meaning. It says you have a missing bond between the water and the coping. Doing the same test between all components of the EP Bonding noting any voltages. Again if components test are bonded you should have a 0V reading.

Running a conductor between the coping and the nearest access to the EP Bonding and retesting the "water to coping" and see if it changes, if not, do the same to the water. The voltages should be reduced or eliminated ( a wire into the water will have limited success to create a good electrode for the test but should be enough to see if there is a change.)
Identify the missing bond and correct.
Same test procedure for any other components that have a voltage present, and correct.

 

[retirede]

I drilled a hole to the steel edge of the pool shell and I'm seeing 300 ohms from this point to the bond loop about 8 feet away using a #8. The numbers just bounce around to approximately 1400 on the bare coping a couple inches away measured in the same fashion.

Seeing 800 ohms to this same point approximately 40 feet away on the coping adjacent to the pool equipment.
Seeing 200 ohms to the steel wall at the same location to the same point 40 feet away. Ohm readings were taken with a digital multimeter.

If I’m understanding correctly what’s being measured here, these readings are problematic and point to incorrect or failed bonding.

Everything that’s bonded together properly should show a resistance near zero.

 

[Trickyrick33]

Really until you are able to validate which components of the EP bonding (Equipotential bonding) that are not linked, the reading to remote earth are not useful overall. You normally will have for a variety of reasons as previously mentioned for voltage differences. Thus the requirement for EP bonding.

This could be a failed reading, poor connections. A reading like this is what you want to see between components of the EB Bonding, but not necessarily from a component to remote earth.

Remote Earth test has limited help overall as the EP Bonding is designed (or should be) to bring all related components to the same potential (Bird on a wire) to prevent shock regardless of the voltages to remote earth are. EP Bonding done correctly, you could have 120V introduced into the pool and not receive a shock from any contact within the pool bonding area between components of the EP Bonding. The reason for the shock you are reporting is a difference of potential between the components.

Your multiple DC readings between components is indicative of galvanic response from dissimilar metals used in the pool structure and being salt water pool this effect can be enhanced. (This is equivalent to creating a battery with the pool structure.) Look for components showing excessive corrosion or even blackened components. Some component can even be totally disintegrated. Shell of Aluminum or steel and water bond of brass or copper will create such effect. But your use of the cheap Southwire meter is not a real test as the readings are easily negated by the range of +- tolerance of the meter.


This is the only reading that really has a meaning. It says you have a missing bond between the water and the coping. Doing the same test between all components of the EP Bonding noting any voltages. Again if components test are bonded you should have a 0V reading.

Running a conductor between the coping and the nearest access to the EP Bonding and retesting the "water to coping" and see if it changes, if not, do the same to the water. The voltages should be reduced or eliminated ( a wire into the water will have limited success to create a good electrode for the test but should be enough to see if there is a change.)
Identify the missing bond and correct.
Same test procedure for any other components that have a voltage present, and correct.

I borrowed a Fluke 117 multimeter. My voltage this morning from the water to coping was .5 VAC. I drilled a hole to the exterior steel pool shell and attached a #8 from this point back to the bond wire. The voltage from water to coping went to 0 on 1/2 of the pool. I drilled another hole on the other side and attached another #8 to the bond wire and the voltage dropped to 0.

However I’m seeing .2 VAC from water to the concrete deck when it’s wet. It increases by a few hundredths for every couple feet I move away from the water.

 

[Trickyrick33]

Just a follow up, I managed to find the wire mesh in the concrete. I attached it to the bond loop and the voltage went to 0 for about 2/3 of the concrete deck.

I’m now seeing .03 VAC on the remaining 1/3 of the deck with one spot at .06 VAC. This is to dry concrete. Those same spots wet are at .25 VAC.

Strangely enough, I get .02 VAC with just the one lead in the water and the other is the air.

 

[ptonsparky]

Just a follow up, I managed to find the wire mesh in the concrete. I attached it to the bond loop and the voltage went to 0 for about 2/3 of the concrete deck.

I’m now seeing .03 VAC on the remaining 1/3 of the deck with one spot at .06 VAC. This is to dry concrete. Those same spots wet are at .25 VAC.

Strangely enough, I get .02 VAC with just the one lead in the water and the other is the air.

.02 is meaningless.

 

[Trickyrick33]

.02 is meaningless

.02 is meaningless.

If I remove the temporary bond wire to the steel shell the .03 VAC on the deck shoots up to around 1VAC. Once reattached the numbers come back down. Wouldn’t this indicate the wire mesh is bonded in this area? I’m trying to decide if I want to cut more concrete in this area to attach another bond wire in this location.

Are these .03 to .06 readings inconsequential?

 

[jim dungar]

Are these .03 to .06 readings inconsequential?

You need to see the accuracy specs for your meter.

I would not be surprised to find most 'affordable' hand held meters are not going to be accurate to 3 significant figures , much less 2 decimal places.

 

[Trickyrick33]

You need to see the accuracy specs for your meter.

I would not be surprised to find most 'affordable' hand held meters are not going to be accurate to 3 significant figures , much less 2 decimal places.

I found the wire mesh on the other side of the pool. The dry concrete originally at .06 AC is at 0VAC with this wire attached to the bonding. Wet it goes to .046 VAC. All other dry spots are showing 0 VAC.

Meter is a Fluke 117. When I measure in the auto setting it only reads 0 for everything wet or dry. When I move it to the manual AC voltage setting I see the .046 VAC.

 

[jim dungar]

I found the wire mesh on the other side of the pool. The dry concrete originally at .06 AC is at 0VAC with this wire attached to the bonding. Wet it goes to .046 VAC. All other dry spots are showing 0 VAC.

Meter is a Fluke 117. When I measure in the auto setting it only reads 0 for everything wet or dry. When I move it to the manual AC voltage setting I see the .046 VAC.

What voltage range are you using?
That meter says its resolution is 0.1V on Auto Volts and 4 significant figures for the other ranges. Its accuracy on Auto Volts is about 2%.

 

[ptonsparky]

Are these .03 to .06 readings inconsequential?

IMO, Yes.

 

[Trickyrick33]

I managed to eliminate all of the AC voltage issues from water to coping and from water to the concrete deck by attaching new bond wires to two points on the steel wall as well as two points to the wire mesh in the concrete on both sides of the pool.

However, after a good rain this afternoon I’m now showing .5V DC from water to coping and from the water to the exterior bond loop. How could the new bonding eliminate the AC voltage but not the DC voltage?

 

[ramsy]

showing .5V DC

Not reliable, unless meter reading uses a low impedance setting.

 

[Raine_EE]

How old is the pool?
Is the soil corrosive?
Do you have issues with ug conductors (neutrals, grounds) getting eaten up over time?
The electrical resistivity of soil can depend on the moisture content.

 

[drcampbell]

... I'm seeing 300 ohms ... Seeing 800 ohms ... Seeing 200 ohms ...

Accurate resistance measurements are not possible with a high-impedance DVM when there's voltage on the circuit.

You might get halfway accurate resistance measurements with a large battery -- with a significantly higher voltage than the stray voltages -- and a milliammeter, though I doubt they'd be terribly relevant.

 

[mtnelect]

With the Utilities MGN (Mult grounded Neutral) system you will never get rid of it, no matter how much you try !

 

[Trickyrick33]

Not reliable, unless meter reading uses a low impedance setting.

Meter is a Fluke 117. On LoZ/Auto function voltage is at 0.0 this morning but it was at 0.1 yesterday after a hard rain on the same setting. On the manual setting voltage is 0VAC / 0.5 Volts DC.

The new bonding eliminated to the AC voltage I was seeing before. Are the DC readings concerning or are they inconsequential?

 

[ptonsparky]

Meter is a Fluke 117. On LoZ/Auto function voltage is at 0.0 this morning but it was at 0.1 yesterday after a hard rain on the same setting. On the manual setting voltage is 0VAC / 0.5 Volts DC.

The new bonding eliminated to the AC voltage I was seeing before. Are the DC readings concerning or are they inconsequential?

Inconsequential.

 

[jim dungar]

Meter is a Fluke 117. On LoZ/Auto function voltage is at 0.0 this morning but it was at 0.1 yesterday after a hard rain on the same setting. On the manual setting voltage is 0VAC / 0.5 Volts DC.

The new bonding eliminated to the AC voltage I was seeing before. Are the DC readings concerning or are they inconsequential?

My limited experience has been that DC voltage comes from the chemicals in the water effectively creating batteries between metallic/conductive materials.

 

[roger]

My limited experience has been that DC voltage comes from the chemicals in the water effectively creating batteries between metallic/conductive materials.

Which is a good reason to have sacrificial anodes on your boat