Shocking find this may save a life

Thanks all...this has been a very educational thread...

 

Jeez, you do know your %$^%$#$#. Cool. Thanks man. I appreciate.

 

Not to make waves, but to join the fray, electricity is not always easy to understand. Voltage is a difference in potential, meaning at its most elementary terms, a magnetic difference.

Turn off the breaker, cut a plugged in electrical cord with scissors, then turn the breaker back on. (OF COURSE DON'T DO THIS!!!) There is voltage in that cord! There is no current presently, but electricity is infinitely patient, and as soon as a circuit presents itself, it will travel on it. That circuit can be a TV or other appliance, or you.

Voltage CAN indeed be present without current. One only needs to get close to a live, downed power line to experience this firsthand. The Greenlee tick tracer that someone wrote about a few posts back will detect the presence of that voltage, which comes in handy when there's no current.

Voltage does need to be measured across a completed circuit, but a completed circuit is always just waiting to happen. Take our downed power line; to measure the voltage "across" it, you place one end of your voltage meter on the hot end, and the other end to a suitable ground.

The bird on the wire indeed has no potential difference in its body, but if you put your voltmeter in its mouth and put the other end to ground, you'd read 26,000 or 14.5K, or whatever voltage line the bird happens to be sitting on. It doesn't get shocked because it is at the same potential as the line. There is no potential difference within the bird--but if it touches wings with another bird on a different 26K voltage line, both birds are incinerated in a flash of light and smell of burnt feathers on the 52,000 volt circuit they just created.

If you've ever seen on the Discovery Channel, men working from a helicopter on an ultra-high voltage distribution line, it's amazing to fathom, but simple ohms law. The helicopter is physically attached to that line--and is thus like the bird on the wire. As long as they don't touch ground, the very topic of this thread. . .they're all safe. Technically, that man can go home and tell his wife that he was 52,000 volts today. He could tell you that he had 52,000 volts in his body, but as Bogie can tell you, he had no current flowing through him, and that's a good thing!

The National Electric Code takes voltages into consideration when setting the minimum distance between hi-voltage distribution lines. For the most part, it's greater than the wingspan of two birds.

 

Neat-o. Thanks Sparky. Between yourself and Bogie, now I have a basic understanding. My boy was asking about the bird on a wire thing just the other day. I can explain it to him now. He seemed perplexed when I uttered the words, "I have no idea.". He is starting to realize that Dad does not know everything.

 

Good call ReefSparky. I guess what I had really meant to be saying was that there is no voltage without current in a closed circuit. So you can't just take the last 4 inches of wire that's at the end of a live line and measure the voltage between the end of it and 4 inches in from the end. That voltage potential difference would be zero, or the same. It would only read a difference of 110 volts if measured between there (~110 volts) and ground (~0 volts).
So voltage can be there without a complete circuit. Otherwise, the voltage detector wouldn't work, right? I guess it really measures the presence of an electro-magnetic field.

The reason that there is no current is because there is no conductor. Now put this into our discussion of a ground probe in a saltwater tank or sump. Saltwater is a great conductor, the higher the salt/ion concentration, the better a conductor it is.
If there was a voltage potential AND a conductor, electrictiy would flow from high potential to low potential through the conductor (wire, bird, saltwater, human...) that has the least resistance.

And I did see that video of the guy working on the high voltage wires from the helicopter. He had a conducting rod to charge himself in his suit to the same voltage the lines were at. It's all safe. I don't like heights, so to me that's the dangerous part.

 

sparky, glad you cleared that up. I was about to create some crazy ranting post that probably wouldn't have made much sense to the people on this forum..
for the record bogie, I am an electrical engineer. I work with and design high voltage substations.... so to answer your question-- "Do you even know what voltage is or how to measure it?" -- yes.

 

So explain it then....
Where are you measuring this 110 or 120 volts to and from if there is no closed circuit?
On a closed, grounded circuit it will read 110V between hot and ground, but open there is nothing you are measuring against...

 

wow electrical people get heated when arguing glad i took computer science instead people are alot more easy going lol.
i was wondering is there a optimal position for the ground probe in the tank?

 

yes, placed in the saltwater, sostoudt.

 

OK, I am going to preface that when it comes to this, I AM AN IDIOT. There, that said, here is my take reading the past posts.

There is measurable voltage in the bird on the wire, right? It is an open circuit. Thus the bird is alive. Once the circuit is closed and completed, the voltage is still there, but now current exists as well (who's power is expressed as voltage, which is no longer potential). Both voltages are measurable to ground in both an open and closed circuit, it's just that the potential is there (open), or not (closed).

OK, I am ready to get thrashed.......GO!!!!!