Thread: For the scientifically minded...

Originally Posted by gugi

Watt is the unit for power, i.e. the rate of energy being dissipated. It depends exactly how is that energy dissipated. It's just the voltage multiplied by the current (or using ohm's law any other combination with the resistance), so if you know the property of the material at hand i.e. the resistance, generally you can work out what the distribution of current through it and what energy will be dissipated in different parts, when a given volgage is applied.
But as MickRussell said, it's fairly complicated problem for a human body.

Let me run that through the HNSB translator:

Originally Posted by gugi

This stuff is too confusing for you. Go have a donut.

Thanks for clearing that up for me!


Edit: I just recall from an electronics class in high school that V*A=W. I didn't realize that the amps were variable, or related to resistance. That was probably covered too, but there was this girl that sat at the table next to me, and... well... let's just say I didn't learn a lot.

Originally Posted by roughkype

...

I'm just starting my electrical career (4 years in at age 46). Scary stories by you. Sorry to hear of the trouble you had, man.

I've had all manner of burns, bruises, breaks etc but the one I mentioned happened when I was working live in a switchboard that someone else built. Some rubbish fell out of the duct work (which I've always been pedantic about cleaning out for this reason) and shorted across 3 phase, 415v mains about 18 inches from my face. since the 1000A breaker was only a couple of yards from me and the main supply transformer only about 20 yards from that there was a reasonable amount of fault current. The flash took off the beard on the right side of my face, the surface off both eyes, turned the skin on the back of my right hand into crispy little bits except for a flap on my ring finger that melted and melted my eyelashes together into clumps. I was blind for about five minutes afterwards. It was ... not my finest hour.

This conversation reminded me of that "High power line workers" video a few years back that i'm sure everyone has seen.

Originally Posted by thebigspendur

I was just wondering about this as I got a minor electric shock this morning while working on some wiring.

Next time just dangle your self in the air with a metal Faraday suit.

Originally Posted by Brighty83

metal Faraday suit.

That is repetitive. And redundant. :-)

Very cool video, though.

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.

a) those 'leather' gloves are rubber on the inside... they have a leather covering so the rubber innards won't puncture as easily.
b) that transformer has a throw switch that turns it on via a fiberglass hook pole - probably energized after the meter was plugged in to the base. Linemen are very wary of public sector electricians they don't know, homeowners and others of ill repute that might cause a fireball to ensue due to a neutral feed plugged into one of the phase terminals.
c) safety protocols would have prevented him from working on live voltage without the proper equipment, or in a safe manner...

I once worked for an electrical contractor who had been a lineman for the power company. He burned up more tools than anyone I ever knew because he refused to de-energize cicuits while working on them. I couldn't afford to buy a new set of Kleins every day of the week, but he did. I guess he thought working with 'low voltage' was pretty boring - but those 40 dollar pliers with big holes blown in them weren't that cool in my book.

The last pair I bought was in 2003. I'm sure he's bought 200 since then.

Originally Posted by northpaw

Electricity is really very simple.

It works like this:

...are those anodes running at 720? That'll ring a bell! (been there, done that)

Ah the good old days of RF burns and radio signals bounced around the world...

I once had a pair of 3-500Zs that never came up to their full potential until they were surrounded by a sky-blue 'warp' signature. I'm really surprised I never experienced time travel.

I lost a good pair of pliers from cutting into a live 415v lead. Stupid STUPID mistake. I honestly thought it was dead ... it disagreed and my pliers lost the argument. I obviously unplugged the wrong lead. I still have them as a reminder, it ain't dead till it's been checked TWICE ... at least. Still, I haven't blown up a set of pliers in 8 years now so I can't complain too much.

Originally Posted by Birnando

That is basically right.

To put this in easier language:
I can touch the Live and Neutral in a regular outlet. This will hurt, but represents little danger or damage to a healthy person. The reason is that you connect in paralell, and the resistance in your body is really high.
According to Ohm's law, it shows like this:
Voltage/(Apmps*resistance)
This closed circuit has very high resistance and therefore low current.

Now, the real danger is in a regular light switch.
Touching the two wires in one of those, with e.g. a bunch of lightning fixtures attached to it, is a real danger.
That will make a serial connection, and that means that all current in that closed circuit will pass thru you.

Believe you me, you do not wanna try that at home. I've lost 2 colleagues this way, a very nasty way to go...

A current as low as 30mA (that's 0,003A) could be potentially leathal, so beware

Actually, you got that backwards my friend.

If you leap yourself onto the black and white lead (US standard) of an otherwise unhooked electrical circuit you have entered yourself into a series connection and have become the load. It's all you, baby! Ride the Tiger!

If those wires are connected to lighting circuits - or other circuits that are in use - you are hooked up parallel. You'll get the same ride as you would in series. Your load is just added- by about half in fact - to the load that's already in use, but you are just one component of the 'new' circuit. Ohm's law is a constant in the universe.

If however you decide to open up the return and jump into series with that Tiger... let's hope you wake up after you hit the walls.

I always tell my guys to beware of the white wire. That black one will bite, but if it's still hooked up the white one will clack your nuts together and tattoo their names on your forehead.

I suppose any voltage that hits home 'could' kill, but up to 277 you'll instinctively let go. You might have to wash your mouth out with soap, and add an extra bit to the wash to clear out those undie scars, but you will let go.

Higher voltages and you run the risk of having your motor functions altered. If you can't let go, that's a bad thing. Very bad.

Originally Posted by MickRussell

I lost a good pair of pliers from cutting into a live 415v lead. Stupid STUPID mistake. I honestly thought it was dead ... it disagreed and my pliers lost the argument. I obviously unplugged the wrong lead. I still have them as a reminder, it ain't dead till it's been checked TWICE ... at least. Still, I haven't blown up a set of pliers in 8 years now so I can't complain too much.

Speaking of leads...

That 'lineman' I used to work for found himself in an 'industrial' predicament when the client was not being made happy because his 3 phase 480 metal cutter was running backwards. I stopped by and swapped two of the leads and everybody was made happy.

I'll be the first one to ram some fingers into a box and pull out some leads, but I'd NEVER stick my pliers in there. I might get a shock, but if my pliers get a shock I'd have to buy new ones...



I did keep an old pair of channel locks I blew up early in my career - only because the hole I blew in them facilitated the perfect removal of the plastic Romex sheath leaving the ground wire exposed... perfect for attachment to a fish tape for old work, or insertion into new wiring boxes.

Sadly, one day I dropped them inside a new wall and in 1000 years they'll be found and entered into some text book as a great find.... I should have dropped a razor in there too... would probably make for a good story for someone... if they could ever figure it out...

I've considered dropping a bunch of really random things in a capsule just in case they're dug up in a thousand years. I'd love to watch them try to work out why an early 1800s razor, electronic watch and a petrified condom are together in a titanium tube. lol