High Voltage and Rain

Some of it does. Even more of it does when it's raining. Try the following experiment:

• stand and wait for a train at a railway station where the line has overhead electification in rain while carrying a metal umbrella, and bring part of the frame just into contact with the top of the head. Feel the tingle? Hear the insulators fizzing? The body is forming a path to earth/ground for all that electrical energy flying about.

It's enough to make one's avatar bounce up and down!

The fact that the steel poles are isolated from the phase conductors by the phase to ground insulators. The steel poles are solidly grounded (as are the ground ends of the insulators). When the insulator surfaces become heavily contaminated by water soluble salts, there may be resistive leakage currents to ground flowing over the surface of the insulators under conditions of light wetting (fog, dew, mist, etc.). Those currents may be on the order of a few milliamps but are of no concern providing the pole remains solidly at ground potential.

If you live near any towers, If it is foggy in the night, an old insulator may buzz a bit, and if it is dark enough you will see a blue hue around it as well! (Sorry, that was a terrible example of how English should not be used!)

Nice reply Bluestone! I'll give you my vote!

Excellent reply.

Between the steel pole and the wire is an insulator. These are usually brown or grey, and may either be a single stiff piece or a series of bell-shaped pieces. Depending on the voltage of the line, they may be 10 cm to 4 m in length. The insulator is designed somewhat like a stack of cones, with a separation distance between the larger end of adjacent cones. This gap prevents the raindrops from making a continuous path for electricity across the insulator.

There are 2 different distances which designers must take into account. Strike distance is the minimum required separation in air from any live part to any ground, to prevent an arc. This is a straight-line measurement and varies directly with the design voltage. Creepage distance is a measurement along the surface of the insulator, where rain or other contaminants could cause a continuous path for the electricity to the pole. Creepage takes into account the "zig-zag" path the electricity must take, into and out of the bottom of the cones, to get from the live wire to the pole along the surface of the insulator.

The insulator is designed to provide enough resistance, even with the rain, to prevent significant amounts of electricity from reaching the pole. In areas of heavy air pollution or other airborne conductive material such as salt spray, engineers must specify insulators with larger strike and creepage values to prevent failure.

When I was a teen (about 1972) I walked under a cross country transmission line near Henry Va while wearing a zip up nylon jacket with a hood. I heard a hum and crackle with the hood up. It was so loud at first I pulled my hood off to see where the sound was coming from (excuse my grammar). The sound came and went with the hood.

As for steel towers, I also had a friend whose father was a lineman for Apalachian Power in those days who said creosote poles were about 90% conductive. Strange units though, 90% compared to a copper pole of same cross section stuck in the ground? Anyway they were conductive enough to knock him silly on the pole he was climbing when he came in contact with 7700VAC.

jh

Here is a job with high potential...

http://www.flixxy.com/helicopter-cable-inspector.htm

I checked out the video. Was the arcing from the power line voltage or the static electricity generated by the helo. rotors?

Static electricity from rotors, I believe.

Not personal experience, but I recall talk that navy personal have to be carefully to allow a line lowered from a helicopter to touch the hull before they grab it otherwise they call get zapped from the discharge. But at the same time I don't recall anyone of the number of CH-47 crewmembers (CH-47 is US Army's heavy lift helicopter, used for sling loads all the time) I know talking about that. Wonder why?

Static electricity is only part of it. The arc is caused by the difference in potential between the phase conductors and helicopter. The object of the rod is to bring the lineman on the platform and the helicopter to the same potential as the conductors. Note the lineman is wearing a conductive suit. After bonding to the conductor, the lineman and helicopter are energized at the same voltage as the conductor and remain in that condition until the bonds are removed and the helicopter backs away. The arcs are directed to specific, non-critical termination points and arcing to those locations continue until distance is such that the voltage can no longer sustain the arcs and the arcs extinguish.

Similar procedures are employed for live-line barehand work from structures and bucket trucks. It's the bird on a wire principle and I had the privilege of knowing and working with the engineers who developed the live-line barehand technique. Dr. Charlie Miller was the first to clip onto an energized EHV transmission line in the Ohio Brass Company high voltage laboratory in Barberton, OH in the 1960's.

How do you advertise for that job position?

Want to work Outdoors feel the wind in your hair. Not afraid of heights. Have we got a job for you.

Job looks like it would be interesting. But not for me.

Looking for a high-flyer with an electric personality who won't be too shocked by the job content?

WOW! I want a go on that! I've done tower work and pulled myself along on a dead line using a pulley, but that tops it off for me!

From accounts I have read, the first to purposely charge himself to high voltage was Nikola Tesla. He used to entertain friends such as Edison, Westinghouse, and Twain at his New York laboratory (after a night of drinking) by charging himself so full of high voltage that coronas exited from every orifice of his body.

I've never heard that one, but sounds rather amusing. One disputed thing though; I don't thing Tesla considered Edison a friend, especially after he ripped him off and then tried to discredit his inventions.

AC man displayed his inventions in that fashion , it was not his body but globe through which caronas were displayed , DC man was his employer initially , than partner , than ? AC & DC are different parameters man

You guys have really done a great job answering my question. As a reward, let me introduce you to Mr. Whack!!! My apologies to anyone who has already seen these...

Whoops! How did she get in here!!! Oh, well... Consider it a bonus!

Pure rain water and snow are not conductive. If it is contaminated, with salt for example, then you have a problem. The utilities depend on rain to keep insulators clean.