Grounded conductor (neutral) and earth voltage

[kwired]

This makes sense. I’m going to study it again and knowing this will help.

If you were to place many ground rods in succession and maybe create some sort of bonding of the entire earth from the rod at the house all the way to the rod at the transformer, then you couldn’t get a difference in potential between a hot conductor shorted to the ground rod and ground surrounding it, right? Would that be comparable to equipotential bonding by eliminating touch potential of the ground rod?

Is a step in the same direction as creating an equipotential grounding system around the pool. Steel encased in concrete in general will still have lesser resistance to earth than a rod that has less contact with the earth.

then you couldn’t get a difference in potential between a hot conductor shorted to the ground rod and ground surrounding it, right?

You still have potential between this and the "hot conductor" and it is most if not all the potential that the system normally sees between that particular ungrounded conductor and the grounded conductor of the system.

What you are doing is keeping the area near those rods closer to whatever potential the grounded conductor is at the point you connected to it.
If there is no current on the ungrounded conductor then that potential is very near earth potential. If there is current on the grounded conductor then there is a voltage drop on the ungrounded conductor, which will make the voltage to earth equal to the amount of voltage that has dropped across the grounded conductor, presuming it is also has a ground reference at the source.

 

[Fred B]

There is some significant misunderstanding by OP related to Bonding and Grounding vs Equipotential Bonding and neither are alike other than a connection that is "electrically" continuous between points.

Bonding of the electrical system is to provide a electrically continuous connection of the normally non current carrying parts of the electrical components and system that helps to provide a low resistance means for a fault to be cleared.
Grounding of the electrical systems is a connection to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.

The EP bonding is to provide a means to put everything within the reach of the area to be bonded at the same potential and thus prevent a flow of current that could be a danger to persons or animals (Farm application) due to a difference of potential between point A and B with both being within reach. EP bonding is even done at utility substations, Utility Solar farm, and Utility Wind farm equipment. EP Bonding on a pool or even a structure such as a barn, even if no power supplied equipment are present, is beneficial as there are times a NEV potential is present from the utility service. Seen on a pool that had voltage present even with everything electrical disconnected from the pool, source was from Utility neutral being compromised and once repaired voltage was eliminated.

To illustrate the need for EP bonding You can measure the "step potential" from an energized point at earth to a distance from that point along the earth gradually reducing the farther from the source point, and will vary depending on soil conditions. Example: If source point is at 120V 1 ft away could be 110V 2 ft @ 90V 3ft @ 75V, So a single stride could provide 45V between the one foot and the other foot in this scenario, and a shock hazard. If in a swimming pool it could be enough to cause shock drowning as that can occur with just milli-amps of current.

 

[Bro8898]

You can do it in someone's backyard or around a barn but you can't make the whole 500 square mile county an equi-potential plane.

Good point. This is helpful.

 

[Bro8898]

neither are alike other than a connection that is "electrically" continuous between points.

Thank you for pointing this out. I’ve been trying to understand one in order to understand the other and I think it helps to separate the two concepts.

EP Bonding on a pool or even a structure such as a barn, even if no power supplied equipment are present, is beneficial as there are times a NEV potential is present from the utility service.

This is good. And answers what I was originally asking. Although I did think it also applied to a current carrying conductor coming in contact with the ground and causing a shock hazard for someone in the water. I may need to rethink that.

Example: If source point is at 120V 1 ft away could be 110V 2 ft @ 90V 3ft @ 75V, So a single stride could provide 45V between the one foot and the other foot in this scenario, and a shock hazard.

I assumed that the potential voltage difference would increase as one’s feet were further apart. Meaning if you hop on one foot or keep both feet together there is less of a voltage difference than if you stand with both feet two feet apart. I may need to get a better understanding from what I was thinking. I will read and inform myself on this and come back.

Thank you so much for your teaching.

 

[kwired]

Example: If source point is at 120V 1 ft away could be 110V 2 ft @ 90V 3ft @ 75V, So a single stride could provide 45V between the one foot and the other foot in this scenario, and a shock hazard.

The reason we do this in art 547 applications is things like cows have four feet, don't wear any shoes, and can span across more voltage gradient in the surface they are standing on than what people do standing on only two feet.

Swimming pools simply have enhanced conductivity and being immersed in the water enhances conductivity of user's skin as well, which makes it possible to span across more voltage gradient easier than in most other situations

 

[Bro8898]

can span across more voltage gradient in the surface they are standing on than what people do

Can you explain the statement you quoted above? Is this saying that the farther your feet are apart the greater the potential difference in voltage and opportunity for more current to flow when both are touching the ground?
If source point is at 120V 1 ft away could be 110V 2 ft @ 90V 3ft @ 75V, So a single stride could provide 45V between the one foot and the other foot in this scenario, and a shock hazard.

I read a paper by someone named Zipse about neutral current flowing through the earth. Is equipotential bonding a way to decrease the negative effects of neutral current flowing through the ground?

Thanks

 

[don_resqcapt19]

Can you explain the statement you quoted above? Is this saying that the farther your feet are apart the greater the potential difference in voltage and opportunity for more current to flow when both are touching the ground?
If source point is at 120V 1 ft away could be 110V 2 ft @ 90V 3ft @ 75V, So a single stride could provide 45V between the one foot and the other foot in this scenario, and a shock hazard.

I read a paper by someone named Zipse about neutral current flowing through the earth. Is equipotential bonding a way to decrease the negative effects of neutral current flowing through the ground?

Thanks

that would have no effect on the current flowing in the earth.

 

[wwhitney]

that would have no effect on the current flowing in the earth.

I agree there would be no practical effect on the current magnitude, but if the current is causing a voltage gradient, the equipotential bonding should reduce that voltage gradient, yes? By replacing the resistance of the earth with the resistance of the bonding conductor, and so lowering the voltage gradient per unit length per unit current.

So, in that sense, yes, the equipotential bonding will decrease one of the negative effects of the current, namely the voltage gradient it causes.

Cheers, Wayne

 

[don_resqcapt19]

I agree there would be no practical effect on the current magnitude, but if the current is causing a voltage gradient, the equipotential bonding should reduce that voltage gradient, yes? By replacing the resistance of the earth with the resistance of the bonding conductor, and so lowering the voltage gradient per unit length per unit current.

So, in that sense, yes, the equipotential bonding will decrease one of the negative effects of the current, namely the voltage gradient it causes.

Cheers, Wayne

Yes, reducing the gradient or step potential is the most common purpose.
I was reading it as the overall issues in the earth that Zipse often wrote about...most notably neutral to earth voltage.

 

[Flicker Index]

Something that is common with sound and video system is when current in the order of several amperes flow where it shouldn't and interferes with signal circuit.

For example, if the power amplifier is plugged into an outlet there, and its hooked up to a piece of instrument that's plugged into a different grounded outlet, there maybe a half volt difference.

Another common example is horizontal bars on TV from current flowing through the chassis due to a few amps flowing between grounded coax and grounded chassis.

 

[Flicker Index]

Can you explain the statement you quoted above? Is this saying that the farther your feet are apart the greater the potential difference in voltage and opportunity for more current to flow when both are touching the ground?
If source point is at 120V 1 ft away could be 110V 2 ft @ 90V 3ft @ 75V, So a single stride could provide 45V between the one foot and the other foot in this scenario, and a shock hazard.

I read a paper by someone named Zipse about neutral current flowing through the earth. Is equipotential bonding a way to decrease the negative effects of neutral current flowing through the ground?

Thanks

Wrap the long ends of a sub sandwich with tin foil, then attach the ends to a doorbell transformer. For the purpose of this demo, leave the secondary floating (not grounded).

The current flowing through the bread is "constant". Jab your voltmeter probes at any two points in the bread. The farther apart the probes, the higher the voltage "step potential" you'll see, thus higher the current flowing through the meter. The step potential doesn't have to be at a dangerous level for it to cause behavioral effects on livestock.

 

[ggunn]

The reason we do this in art 547 applications is things like cows have four feet, don't wear any shoes, and can span across more voltage gradient in the surface they are standing on than what people do standing on only two feet.

How Lightning Can Kill 300 Reindeer With One Strike

It all comes down to some basic principles of electromagnetism—and some unfortunately placed permafrost.

www.wired.com

 

[Bro8898]

The current flowing through the bread is "constant". Jab your voltmeter probes at any two points in the bread. The farther apart the probes, the higher the voltage "step potential" you'll see, thus higher the current flowing through the meter. The step potential doesn't have to be at a dangerous level for it to cause behavioral effects on livestock.

So if I were to put a clamp around the bread (or the wire) it would be the same current no matter where I placed it. But if I put each lead of the meter into the bread I’ll see a greater voltage difference the farther apart I place them, and thus more potential for current to flow.

In this statement it seems that the farther away the leads are the less voltage there is between them, am I interpreting it incorrectly?
120V 1 ft away could be 110V 2 ft @ 90V 3ft @ 75V