Our Fearless Leader Mike

[Peter Furrow]

You're forgetting that everything, including the EGC, is at the same potential once bonded. If you lift the EGC on the motor (if it's not double insulated) you present more of a risk if there is a fault at the pump motor.

If the equipment grounding conductor was lifted off of the pool motor and there was a fault then the entire equipotential bonding system could become energized. In this situation the swimmer would not be shocked because he would be swimming in 120v & standing on the pool deck that had 120v. However, if there is a potential difference on any metal part such as a screen enclosure and he touches it ,Then he’s “screwed”.

However, I do agree that the equipotential bonding and the equipment grounding system should be bonded together. But, NEC does not require them to be bonded together at the panel. The only point where these two come together is at the pool pump motor.
But let’s say they are connected together and utility has an open neutral. In an open neutral situation the grounding electrode system and grounding have been known to become energized. In that situation with the equipotential bonding system and the equipment grounding system bonded together that would mean that the entire pool can become energized .But no one would be shocked because there’s no potential difference as long as everything is bonded together.
FYI .
I really don’t know what the hell I’m talking about Lol!


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[ActionDave]

If the equipment grounding conductor was lifted off of the pool motor and there was a fault then the entire equipotential bonding system could become energized. In this situation the swimmer would not be shocked because he would be swimming in 120v & standing on the pool deck that had 120v. However, if there is a potential difference on any metal part such as a screen enclosure and he touches it ,Then he’s “screwed”.....

That's not how it works. The EGC can stay attached to the pool motor and so by default the bonding grid is connected. If there is a hard enough fault the breaker feeding whatever trips. If there is not enough of a fault to trip a breaker the water in the pool, all of the metal parts, and the concrete deck within three feet of the pool's edge all rise to the same potential so no current flows. At 120V this won't work anywhere else, at a light pole or a boat dock for instance, but a swimming pool it is different.

 

[Peter Furrow]

I did watch a bit of the video and did see the point where Mike is doing the step potential test with himself as the meter. I saw him say "I'll let you know when I feel it". That was over my limit.

I did want to see the actual hands on of how they floated the equipotential grid, and then connected the 120, and especially with a clamp on Amp meter on the power source because even floating I am pretty sure there was still some current flow (to earth and then to the system bonding jumper). Unless they also floated the system bonding jumper, and if so, I would say "A good magician never reveals his secrets".

If the source 120 had a system bonding jumper, even floating the grid will still give some current flow, but maybe not (through the pool water while someone is swimming in it). Floating the power source, then floating the grid, connecting the two and swimming in it, that's a magic trick.

In Mike’s video did he say that they floated the equipotential bonding grid? How would they have done that?
But even if you float the equipotential bond and apply 120 V to the water as they did ,
there’s still two potential hazards.
1st, If there was a utility stud pole nearby it would have a ground rod and a solid conductor attached to the primary neutral. The 120 V in the water could flow through Mike and try to return to the source of the utility stud pole to the primary neutral. Of course the soil would have to be damp enough to be conductive from the pool shell all the way back to the stud pole primary neutral.
2nd , The equipment grounding conductor & the equipotential bonding system is bonded together at the pool pump. When 120 V is applied to the water it’ll go through Mike , through the equipotential, onto the casing of the pool pump motor, to the equipment grounding conductor in the motor, to the pool panel, and back to the service equipment, back to the utility transformer primary neutral.
The voltage always wants to go back to the source.


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[__dan]

In Mike’s video did he say that they floated the equipotential bonding grid? How would they have done that?
But even if you float the equipotential bond and apply 120 V to the water as they did ,
there’s still two potential hazards.

It was not at all clear to me what circumstances were arranged and then what they what they wanted to specifically demonstrate. I can only guess, and that was one of the reasons I would suggest the mouse test. It is pretty easy to go through several variations of swimmable with voltage, the bird on a wire scenario, and then deceased mice from the same experiment with different and kind of obscure but lethal changes.

I started watching the video at about the 50 minute mark as originally posted so I don't know what was shown or discussed prior. I am assuming the pump is usually connected with plastic plumbing so it could have an EGC but then they were claiming the water was at 120, I believe with no wire dropped into it, and the intent was to show that with an properly constructed equipotential grid, there would exist no potential voltage difference within the grid coverage area.

From what was shown, I believe what they did was to float the grid meaning, disconnect it from the supply EGC, and then connect the supply 120 to the grid, so the grid itself (and the water) was at 120 to remote earth. And then Mike went swimming in it, apparently demonstrating no potential voltage difference within the water because of the effectiveness of the equipotential grid. I don't know and don't want to speak for him.

1st, If there was a utility stud pole nearby it would have a ground rod and a solid conductor attached to the primary neutral. The 120 V in the water could flow through Mike and try to return to the source of the utility stud pole to the primary neutral. Of course the soil would have to be damp enough to be conductive from the pool shell all the way back to the stud pole primary neutral.

Yes absolutely there was a lot more going on. If or with the grid at 120 and also if the Voltage supply was also connected to earth (by the system bonding jumper), the resistance of the Earth would have completed that circuit and shown significant current flow. They made reference to this somewhere, talking about a 24 ga wire that melted and blew up like a fuse. I would have really wanted to see a clamp on Ampmeter on the system bonding jumper, which would give a very eye opening reading. I would have to watch again from the beginning to see what they were trying to show.

2nd , The equipment grounding conductor & the equipotential bonding system is bonded together at the pool pump. When 120 V is applied to the water it’ll go through Mike , through the equipotential, onto the casing of the pool pump motor, to the equipment grounding conductor in the motor, to the pool panel, and back to the service equipment, back to the utility transformer primary neutral.
The voltage always wants to go back to the source.
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Again I don't know and did not watch the entirety. With everything connected normally, applying voltage anywere with cause current to flow, there exists "an effective fault (clearing) current path", sufficient to trip the upstream protective device. At one point they talked about seeing 90 Amps and the soffit light fixtures caught fire because (that was the fault current clearing path after they had disconnected the others). I believe they had floated the grid at that point or that would have carried the fault current.

If they had floated the supply voltage at the system bonding jumper, (which may have been at the Utility transformer and inaccessible to them), the system would only reference to ground at the first ground fault (that they created). With a system earthed somewhere but at a remote point, there was step potential Voltage everywhere, which appears to be the actual, and they may have floated the grid and then raised it to 120 (then Mike goes swimming in it).

In the video, I did see what looked like a green #10 or so (THWN) taped to the patio paver tiles and I am guessing that was the temporary connected EGC reference ground. Touching that may have been instantly lethal. He was standing and reaching within 2 ft of it.

 

[Peter Furrow]

I just watched this video again because I really wanna understand it. On the 2nd time ,
I noticed at the 1:04 mark of this video Mikes shock alert detector is not emiting Audible alarm or LED light.
Does anyone know how the shock alert detectors work? Do they just detect voltage similar to the fluke volt tester pen.
Or do they detect actual current only ?


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[DBoone]

At the 46:40 mark, is he saying there are only a handful of electricians out there that truly understand proper pool bonding and safety?

 

[Peter Furrow]

At the 46:40 mark, is he saying there are only a handful of electricians out there that truly understand proper pool bonding and safety?

In context he is making reference to “neutral to Earth voltage “NEV. that’s why he’s encouraging people to watch the stray voltage videos on his site. Mike introduces a troubleshooting strategy to discover any NEV voltage on a pool deck & pool parts when homeowners complain about a slight tingle or shock. Only Handful of electricians out there are familiar with it.
I think most electricians grapple with NEV voltage and the other subject of 120 V supply to the water. However,Most understand the Faraday cage, bird on the wire concept, or voltage gradients. But when it comes to applying 120 V to water ,..electricity behaves a little different. And this is where I struggle.

For example, how come the seven-year-old boy who died in Miami received an electric shock when he jumped in the pool because the light niche had 120 V? When he swam closer to the niche his muscles contracted. What made his scenario different from Mike scenario. Was it because the pool had a equipment grounding conductor in contact with the water in the pool? Was there some sort of return path to close the circuit?

Mike enters the water he’s completely enveloped in 120 V and yet he is not shocked.
It seems like in water 120 V envelops the entire body & there are tremendous amount of parallel paths returning back to the source.
Unlike on dry ground when you touch 120 with the left hand & the casing with the right hand. Electricity will flow between those two points. But in water there are multiple pathways.

Overall, I think I’ve overstayed my visit on this topic. I just grapple with the subject.
I understand....but i dont understand..


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[Peter Furrow]

If anybody comes across any interesting articles on how electricity behaves in water or How electricity flows through a person when they are submerged in water, that would be of interest. This forum has always been really incredible for article posts. It always impresses me how you guys find articles.


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[__dan]

In Mike's case the voltage gradient existed between the equipotential grid and, or to, the remote earth. Within the coverage area of the equipotential bonding grid, which was the pool wall and deck within 3 ft grid, and what it contains, the water, there was zero voltage gradient from point to point and so no current flow.

Think of the equipotential grid and water as one large busbar. There is no voltage difference between any two points on the same busbar, and if you stand on it with your feet apart, you have a zero Voltage gradient between your feet, even as the busbar itself (and you standing on it) can be raised to any voltage above the earth, provided the insulation is working.

In this case the contiguous bonded assembly, the pool shell and the water, were raised to 120 above the earth, and since the earth is a high resistance conductor, there was significant current flow from the grid through the earth back to the supply, system bonding jumper.

The grid and the water were a shunt path while Mike was in the water and the bonding allowed no voltage difference between points within the coverage area. For points not bonded together forming effectively the same giant busbar, there was a Voltage gradient and step potential between the busbar and the earth. The resistance of the earth was limiting current flow to below the trip point of the main.

 

[kwired]

I am wearing shoes so I am not earthed otherwise the gfci would trip. My point was to show how a gfci worked. As I stated I put a wire in the water and touched it to a ground and the gfci tripped. I assume it would do the same if I were connected to ground.

If you are the path current will flow through you.
If current is over the 4-6 mA trip point the GFCI will trip.
4-6 mA through you is still a significant shock, though the duration is limited by the GFCI tripping.

 

[kwired]

In Mike's case the voltage gradient existed between the equipotential grid and, or to, the remote earth. Within the coverage area of the equipotential bonding grid, which was the pool wall and deck within 3 ft grid, and what it contains, the water, there was zero voltage gradient from point to point and so no current flow.

Think of the equipotential grid and water as one large busbar. There is no voltage difference between any two points on the same busbar, and if you stand on it with your feet apart, you have a zero Voltage gradient between your feet, even as the busbar itself (and you standing on it) can be raised to any voltage above the earth, provided the insulation is working.

In this case the contiguous bonded assembly, the pool shell and the water, were raised to 120 above the earth, and since the earth is a high resistance conductor, there was significant current flow from the grid through the earth back to the supply, system bonding jumper.

The grid and the water were a shunt path while Mike was in the water and the bonding allowed no voltage difference between points within the coverage area. For points not bonded together forming effectively the same giant busbar, there was a Voltage gradient and step potential between the busbar and the earth. The resistance of the earth was limiting current flow to below the trip point of the main.

exactly.

There can be voltage drop on a bus bar, but in this case you can not reach far enough to get between those points where there is enough difference of potential that you become low enough resistance for any significant current to pass through you.

Equipotential bonding means to bring everything you can contact to same potential or at least close enough to same that you don't become a lower resistance path. Current may be flowing but is lower resistance around you than through you so any current through you is very low and you can't feel it.

If it were common for people to be 20 feet tall this concept may not work as well as it does for people that are typically less than 7 feet tall, we would be able to bridge across physically larger voltage gradient zones if we were that big, and the equipotential bonding rules would probably extend further from the pool than they do now.

 

[Dennis Alwon]

If you are the path current will flow through you.
If current is over the 4-6 mA trip point the GFCI will trip.
4-6 mA through you is still a significant shock, though the duration is limited by the GFCI tripping.

Not sure why you quoted me because I am pretty certain knew that....LOL

 

[Peter Furrow]

If someone put an equipment grounding conductor in the pool when Mike was swimming would the results have been different for him? How close to the equipment grounding conductor would he have to be before experience electric shock?

There are many cases of people swimming in marinas. They enter the voltage gradient and their muscles constrict.
Is that because there is an equipment grounding conductor or return path back to the source in the water with them.
Is the current traveling through them, through the earth or metal parts and back to the source .?
Are there numerous parallel return paths on their body back to the source that cause all their muscles to constrict?


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[mbrooke]

I have profound respect for Mike. He is a true hero, real educator, an exemplary role model and actually willing to put his knowledge to the test. All people should try to emulate Mike.

 

[Peter Furrow]

I have profound respect for Mike. He is a true hero, real educator, an exemplary role model and actually willing to put his knowledge to the test. All people should try to emulate Mike.

I concur.
I think I’ve overstayed my welcome on this post. I just grapple with all these concepts of swimming with 120 V and how electricity flows through the body. Electricity behaves differently in water especially when it’s threw a person. I’m baffled. I think some of the great gurus of this forum have avoided comments because the subject may be Elementary to them and they’ve got it figured out.
I highly value Mike and his team.
It keeps a bottom feeder like me really thinking.


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[GoldDigger]

If someone put an equipment grounding conductor in the pool when Mike was swimming would the results have been different for him? How close to the equipment grounding conductor would he have to be before experience electric shock?

There are many cases of people swimming in marinas. They enter the voltage gradient and their muscles constrict.
Is that because there is an equipment grounding conductor or return path back to the source in the water with them.
Is the current traveling through them, through the earth or metal parts and back to the source .?
Are there numerous parallel return paths on their body back to the source that cause all their muscles to constrict?


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If there were an earth ground electrode anywhere in the pool there would be a voltage gradient in the water. I both the 120V and earth electrodes were wires, then the highest gradient would be close to either wire. If they were six feet apart, the touch potential difference across the gap between them would be 120V, but the potential gradient would be much smaller if you moved 12 feet or more away from both.

 

[mbrooke]

I concur.
I think I’ve overstayed my welcome on this post. I just grapple with all these concepts of swimming with 120 V and how electricity flows through the body. Electricity behaves differently in water especially when it’s threw a person. I’m baffled. I think some of the great gurus of this forum have avoided comments because the subject may be Elementary to them and they’ve got it figured out.
I highly value Mike and his team.
It keeps a bottom feeder like me really thinking.


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Overstayed? You haven't seen me where I've dragged a thread out into 250 pages asking the same question over and over again "why can 14 gauge wire only carry 15 amps" "why I2R?" "what does thermodynamics have to do with?"

You're not the only one- we all have concepts about electricity which leave use baffled. One for me being lightning strikes. To this day I still don't understand how or why lightning works in relation to grounding and bonding. 12 year researching it and I still don't understand the basic theory or how to apply NFPA 780 to the real world.

But that doesn't mean you should stop trying nor did I say that to discourage you. Because I can assure you we all have our strengths and weaknesses.

Bottom feeder? Some utility poles have two circuits for a reason... both are equally important.

 

[kwired]

If someone put an equipment grounding conductor in the pool when Mike was swimming would the results have been different for him? How close to the equipment grounding conductor would he have to be before experience electric shock?

There are many cases of people swimming in marinas. They enter the voltage gradient and their muscles constrict.
Is that because there is an equipment grounding conductor or return path back to the source in the water with them.
Is the current traveling through them, through the earth or metal parts and back to the source .?
Are there numerous parallel return paths on their body back to the source that cause all their muscles to constrict?


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The whole equipotential bonding concept is to bring everything within reach of pool user to same potential. It doesn't matter if that potential is true earth potential, 10 volts to earth, 100 volts to earth or even 10,000 volts to earth, you won't get shocked if whatever you touch is at same potential as you are.

Now say the entire equipotential bonding system is operating at 20 volts to true earth. You bring that EGC from outside they system in there and assuming it is at true earth you now have 20 volts inside your area you were trying to protect with equipotential bonding system. Depending on situation the EGC might be some other voltage, but we were assuming it is at earth potential. Same thing can happen if you have a "hole" in your EPB system, say you forgot to bond a ladder or diving platform and it is now at or closer to earth potential because of it, yet your entire EPB is 20 volts different - risk of shock goes up.

The situation in a marina is hard to deal with as the marina is impractical to install a EPB system compared to a swimming pool, yet anything you bring to it that may have voltage rise on it is a risk. EGC doesn't carry current normally, but is bonded to the grounded service conductor which is typically also bonded at POCO transformer to a grounded conductor that is part of their primary distribution system. If those grounded current carrying conductors are in fact carrying current they will have some voltage drop on them, and you will almost always have at least a small amount of voltage on anything tied to it when referenced to earth. That is what makes the marinas dangerous and hard to deal with at same time.

 

[__dan]

If someone put an equipment grounding conductor in the pool when Mike was swimming would the results have been different for him? How close to the equipment grounding conductor would he have to be before experience electric shock?

It is a geometry problem. Assuming the scenario, the arrangement under discussion where the equipotential grid is at 120 and an EGC is dropped into the water, the EGC would be a "point source" voltage difference and the surrounding voltage gradient would distribute around the point source as a sphere, as current travels the path (of the closed circuit). So draw the pool, draw a point source of voltage in it, draw the surrounding spherical voltage gradient distribution around the point source, draw the man swimming in it, give him two meter leads one for each hand, record the voltages as he calls them out or as your drawing shows they may be.

There are many cases of people swimming in marinas. They enter the voltage gradient and their muscles constrict.
Is that because there is an equipment grounding conductor or return path back to the source in the water with them.
Is the current traveling through them, through the earth or metal parts and back to the source .?
Are there numerous parallel return paths on their body back to the source that cause all their muscles to constrict?

In the normal scenario out in the field, a body of water is the giant well conducting busbar at earth or zero volts. Stray voltage gradient present is ultimately originating at some point source, but downstream from that point source, the voltage gradient may again appear as a geometry problem. It is distributing in the shape of a sphere or field from the point source. So the gradient extends physically in a geometric shape, at some and many points, distant from the source.

Again draw the marina, dock, body of water, draw the supposed point source voltage, draw a spherical distribution around the point source to represent the voltage gradient, draw someone swimming in it, draw meter leads one in each hand, record the voltages from the meter leads.

 

[don_resqcapt19]

In Mike’s video did he say that they floated the equipotential bonding grid? How would they have done that?
But even if you float the equipotential bond and apply 120 V to the water as they did ,
there’s still two potential hazards.
1st, If there was a utility stud pole nearby it would have a ground rod and a solid conductor attached to the primary neutral. The 120 V in the water could flow through Mike and try to return to the source of the utility stud pole to the primary neutral. Of course the soil would have to be damp enough to be conductive from the pool shell all the way back to the stud pole primary neutral.
2nd , The equipment grounding conductor & the equipotential bonding system is bonded together at the pool pump. When 120 V is applied to the water it’ll go through Mike , through the equipotential, onto the casing of the pool pump motor, to the equipment grounding conductor in the motor, to the pool panel, and back to the service equipment, back to the utility transformer primary neutral.
The voltage always wants to go back to the source.


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He did disconnect the pool equipotential bonding system from any connection to any electrical system. There were days of testing with meters and conductive objects before he ever went into the pool. The testing proved that water in the pool was not conductive enough to flow enough current to create any voltage drop. The verified that every metal part, and even the concrete deck did not have any potentials between them. He really was the bird on the wire when he was in the energized pool...there was nothing that he could contact that was at different voltage than the water.