*Shallow end, being shocked when grabbing railing*

Jump to latest Follow Reply
Have the oscilloscope on the pool while someone is watching it and talk to them by cell phone while you shut off power.

Get permission to shut off power before doing it as there might be issues you are not aware of.
 
And this traffic signal control box looks pretty new (well in 2019). The more I look around the area, I would be highly suspect of lots of stuff at that intersection.


1629307005794.png
 
mas985 said:
Yeah I know, people screw up but the more I think about it, the less convinced I am about an exposed 120v line. That just seems like an extreme cause that someone else would have noticed by now. I think it may be more subtle than that like an unbalanced load (3-phase or split phase) that can also cause stray voltage. There is definitely current traveling underground but it doesn't need to be an exposed wire to cause that.
Click to expand...
Same here. A live exposed wire would blow its breaker or there would be an arc fire volcano bubbling in the pond.

What about our original bad neutral thoughts, but at/near the pond instead ?
 
Looking at Bing maps, I would REALLY suspect that intersection. Although I am sure of the date of this image, but it has been changed a lot. The Google street view seemed to show some lines were also put underground (you can see the conduit and old utility poles next to it.)

1629307407232.png
 
  • Like
Reactions: newdude
mas985 said:
Did anyone else notice the ducks swimming in the pond.

Even though the pictures are two years old, they probably still visit and if that water was energized by 120v, there should be at least one dead duck around that pond.
Click to expand...
What pictures show ducks?

Birds sit on energized wires all the time without harm.

Unless they are grounded, they should not be getting enough current to kill them.

Even if they die, something will probably eat them pretty fast.

There are millions of birds, and some die every day, but you rarely see any dead birds anywhere.

Most likely, it's because something eats them as soon as they die.
 
mas985 said:
Don't think that is legal unless one owns the property.
Click to expand...
Well, I would argue an exigent circumstance existed which required removing a potentially lethal situation. It could be done in a matter of a couple of minutes. I don't see that anyone would be harmed by turning off power to the sump pump for a couple of minutes.

Of course, the OP could figure out who owns it and get permission. ;)
 
JamesW said:
What pictures show ducks?

Birds sit on energized wires all the time without harm.

Unless they are grounded, they should not be getting enough current to kill them.

Even if they die, something will probably eat them pretty fast.

There are millions of birds, and some die every day, but you rarely see any dead birds anywhere.

Most likely, it's because something eats them as soon as they die.
Click to expand...
Ducks...
1629307625705.png
 
  • Like
Reactions: JamesW

Enjoying this content?

Support TFP with a donation.

Give Support
Newdude said:
What about our original bad neutral thoughts, but at/near the pond instead ?
Click to expand...

Unbalanced loads can cause high neutral currents which in turn can cause current to flow through the ground. This happens even if the neutrals are perfect. Power companies try to keep the 3-phases balanced as much as possible to avoid current on the neutral since those lines can be quite long. Residential split phase is not usually an issue because the runs are so short between the homes and transformer (very short in this case) so the voltage differential is minimal. Other types of split phase for utilities could have much longer neutrals and develop voltage differentials. To me this is much more likely than an exposed 120v line.

120v in that pond with a neutral ground right next to it would cause huge voltage gradients so one foot in the water and one on the ground could fry a duck.
1629307531089.png
 
  • Like
Reactions: newdude
mas985 said:
the less convinced I am about an exposed 120v line. That just seems like an extreme cause that someone else would have noticed by now.
Click to expand...
Mike Holt has a video where he drops a live 120 volt line in a pool and it draws 10.35 amps.

He has removed the video, but here is a picture of the amperage being measured.

I think that a live line sending out 10 amps is entirely possible and it would not necessarily be noticed by anyone.

If it is radiating out through the ground and the groundwater, it would be picked up by the ground rods in the area including the pools that act as giant ground rods.

1629307816425.png
 
  • Like
Reactions: newdude
I know it is possible, it just seems unlikely to have gone unnoticed for this long. There are consequences to having that much voltage exposed without it affecting something else. I am not ruling it out completely, just less convinced. One of the neighbors closer to that location should have higher voltage and more probability of being shocked at some point.
 
  • Like
Reactions: newdude
mas985 said:
120v in that pond with a neutral ground right next to it would cause huge voltage gradients so one foot in the water and one on the ground could fry a duck.
Click to expand...
I don't think that the gradients would be that high.

We also don't know how conductive duck feet and legs are.

At this point, we are just speculating and there are multiple potential sources of the stray current.

The high voltage lines and the pond equipment seem like likely suspects and they need to be ruled in or out, if possible.

In any case, the power company needs to get on the case and figure it out.
 
The pond to the OP pool distance is >10x that of the pond to the pole ground/neutral distance so by definition, the gradient would be more than 10x worse than the pool.
JamesW said:
In any case, the power company needs to get on the case and figure it out.
Click to expand...
Agreed. This is definitely NOT something the OP should be fooling around with.
 
A lot depends on what the ground water level is.

If you have ground water two feet down and saturating the entire area, then that will broadcast the current everywhere.

The pool will act like a giant ground rod with a lot more ground contact than the ground rods.

I would disconnect the pool bonding grid completely from the grounds and then test from the bonding grid to the grounds.
 
Yes, the current will travel from every source to every sink. The longer the path length from source to sink, the higher the resistance (if same material). The wetter soil around the point will reduce resistance in all directions. The only point I was making about is that the local ground gradient is higher the closer the source and sink are to one another. It is simple math.

gradient = dV/dL. As distance L decreases, dV/dL increases and visa versa.

So anything close to the source and a sink is more likely to shocked worse than something that is further from the source but the same distance to a sink. Just look at the plots that I did earlier. There is a lot more red near the pond than there is near the pool. This plot is logarithmic so each color change from green to red doubles the gradient per unit distance. So where the pool is, there is a bout a 2v change in contours where as near the south side of the pond, there are greater than 16v changes in the contours (some places 32v). A big difference over fairly equal distances. So you are more likely to be shocked in areas of high voltage changes than you are of low voltage changes.


1629316822915.png
 
Last edited:
Based on that, a few measurements should be able to give a really good idea if the source is where we are thinking or not.

If the source is in the area, the voltage should be significantly high enough to really jump out at you.

If it's not higher, then that points away from the area.
 
Last edited:
JamesW said:
Based on that, a few measurements should be able to give a really good idea if the source is where we are thinking or not.

If the source is in the area, the voltage should be significantly high enough to really jump out at you.

If it's not higher, then that points away from the area.
Click to expand...
I was going to just suggest measuring for voltage at the pond.
 

Enjoying this content?

Support TFP with a donation.

Give Support
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply