Thread: For the scientifically minded...

Okay, thanks for the answers. So explain this to me. A few years ago I had my electric service upgraded and when the guy from the electric company hooked me back up I was shocked-har har as he took the mains coming from the transformer- 600 amps, one wire in each hand wearing only leather gloves. Now how did those leather gloves protect him from that voltage. I thought you needed rubber for that.

Wasn't he holding the insulation, not the metal part of the wire ?

mvcrash, being from North Jersey, may remember about thirty years ago..... A guy working for Public Service , lineman, had just finished doing his job on a pole in one of those bucket trucks. He noticed that the cross member that supports the wires wasn't quite level. He reached out and grabbed it to level it and somehow shorted it out through his arms, burning both off at the elbows. He survived but lost both arms.

Naa I was a few feet from him and he was holding the bare wires and the line was hot.

Was he standing on a ladder or piece of rubber mat?

North Electrical Products / Lineman Safety

He was probably wearing rubber gloves under the leather.

He was standing on the ground, dirt and he was not wearing rubber gloves underneath. Just the leather gloves.

Originally Posted by thebigspendur

He was standing on the ground, dirt and he was not wearing rubber gloves underneath. Just the leather gloves.

I think the obvious answer is that he was a terminator.

Originally Posted by thebigspendur

Okay, thanks for the answers. So explain this to me. A few years ago I had my electric service upgraded and when the guy from the electric company hooked me back up I was shocked-har har as he took the mains coming from the transformer- 600 amps, one wire in each hand wearing only leather gloves. Now how did those leather gloves protect him from that voltage. I thought you needed rubber for that.

Was he holding the main wires going IN the transformer ? (the top wire on the telephone pole) Cuz that's 12kV.... It'll make you dryer than a piece of old toast within seconds. Even rubber gloves wouldn't do much to protect you. But if it's the wires coming OUT of the transformer feeding the bottom wires of the telephone pole, I believe that's 240V. A thick pair of leather gloves should be enough insulation to protect your electrician.

Originally Posted by thebigspendur

Okay, thanks for the answers. So explain this to me. A few years ago I had my electric service upgraded and when the guy from the electric company hooked me back up I was shocked-har har as he took the mains coming from the transformer- 600 amps, one wire in each hand wearing only leather gloves. Now how did those leather gloves protect him from that voltage. I thought you needed rubber for that.

You need insulation/ islolation. It need not be "rubber".

And there may be more that you did not see, notice or know.
Folk that work with the "mains" coming into homes
only get to make one mistake as a rule.

That's one of those, "it all depends" situations. If the ground it dry, his boots are dry, the gloves are thick and dry and his skin is dry then he should get away with it. Also if it's on the output side of the transformer and he hasn't connected the ground side to ground yet then the "hot" wire as you yanks call it isn't hot TO anything yet, so there's no chance of a shock. Remember that voltage is a difference in potential, so any voltage is in reference to another point. Usually that's ground or the neutral (not sure what you guys call that) line. If the other side of the secondary winding isn't actually connected to anything then dragging one wire with your dampened butt cheeks won't get you shocked (except by the police when they show up). This is how "isolation transformers" work. By not referencing one side of the secondary to ground grabbing a bare wire won't hurt you. That 600A transformer secondary, what voltage was it? It's voltage that determines what kind of insulation you need to be "safe". If it was only 110/120v it's not that hard. If it had been an 11kV line that could have been messy. Spectacular, but messy.
Ohm's Law is only part of the story, too. A given supply might only be able to source a certain amount of current regardless of the properties of the attached load. Human skin is also an interesting thing. Typical dry skin has good insulation properties up to about 40V but once it breaks through that benefit is gone and you're just a bag of salt water. Where in your body the current travels depends a lot on what you just grabbed hold of. DC current will flow uniformly up the path of least resistance from entry to exit but AC is subject to something called "skin effect" where the higher the frequency the more current tends to flow in the outer parts of a given path. Really high frequency, say from a variable speed drive (it might be driving a 60Hz motor but the output is usually chopped at around 16kHz), will pretty much peel your skin off and leave your bones alone. DC will cook you nice and even all the way through. DC also has one other property that has always scared the hell out of me as an industrial electrician (big industrial and automation was my "thing"). If AC grabs you the changing current flow will make you "twitch" and tend to throw you off, very handy if you get a little careless, but DC will make your body clench and STAY clenched. Once it's got you, you're boned.
On the matter of currents, 0.003 is 3mA, not 30 (typo I'm sure, but just saying for clarity). It takes 6mA directly across your heart to stop it. Yes, I mean six milliamperes and I do mean DIRECTLY across your heart. Ten amps from one foot to the other might not put those 6mA in a path across your heart (though it very well could, parallel paths though squishy things like people are complicated), but it sure could turn your nads into briquettes.