How am I not dead?

[mapper]

I spent the summer I graduated from high school working in the electrical shop at a pulp and chemical plant. The electricians in the shop called themselves "12 volt electricians", it meant that they would not work on anything live that was carrying more than 12 volts. Anything above 12V had to be turned off and tagged out. Everyone carried tags that were hung on the circuit breakers when they were working on a piece of machinery, it could not be turned on until every tag was removed-and you could not touch anyone's tag but your own!

 

[k0ua]

Have you pulled jumpers on the horizontal side of the frame and got bit on your under arm? Not that much fun but a lot better than catching the 105 AC ringing.

I have been hit so many times with 105 ring voltage it is not even funny. I remember one time sitting in a damp earthen hole splicing a 200 pair at a busy college campus. I was hit dozens of times. And could occasionally feel the -48volts battery thru my tush also up against the damp earth. That was just annoying, but the superimposed ring voltage always gets your attention.

 

[k0ua]

Of course as soon as you are comfortable working around low voltage DC circuits, you can become lax to the danger of getting the crap burned out of you by low voltage high current accidents. One of the guys I worked with accidently got a wrench across the -48 battery plant for a large Central Office before the main fuse. I didn't see this, but he claimed a larger copper bus bar turned white hot in a few seconds and sagged and fell into the floor. Needless to say the CO crashed, putting several thousand subscribers out of service for some time.

It is amazing how fast wires can be heated up with several thousand amperes of current running thru them from battery plants. Many types of batteries have very low internal resistances, therefore they can deliver very large currents for a little while. Of course that is usually accompanied with some severe hydrogen outgassing, making for a very explosive atmosphere. KABOOM!

 

[Soundguy]

t

Soundguy, I'm a lifetime learner. So the answer is yes, and I'm looking forward to it! :thumbsup:

Here's the 10 cent explanation.

If you put your average vom across your wall socket it is going to say 120vac or so.

If you put an oscilloscope on your wall socket, and look at the entire waveform, positive peak to negative peak, you reading will actually be about 340v peak to peak.

The 120v reading is rms, root mean square.

If you look at half the wave form, that is a peak reading. If you multiply peak x .707, you get rms. *(on try some wave of steady frequency )

In short, the rms reading lets you compare to work done or heat rating vs a dc source.

Think of 10 car batteries In series for 120vdc.

Anyway, that's the 5cent explanation I can type on my phone without getting stiff fingers. Yes, there is more to it and you electrical guys know what I've glossed over and why.

 

[prichard]

Is that lesson 1 of 300?

 

[CalG]

I will be happy to demonstrate my left hand on one post and my right hand on the other post of a 12 volt automotive battery all day every day.
When we make blanket statements that it is not the voltage that kills you it is the current, that is not quite true. It is the voltage AND the current that kills you in relation to the amount of resistance to current that you body exhibits that kills you. You must have an understanding of these relationships to know what is dangerous and what is not.

And yes I really will put my tongue across a 6 volt automotive battery. And I will draw no more current than if I put my tongue across a 6 volt lantern battery. Even though the 6 volt automotive battery is capable of producing several hundred times the amount of current.

I don't know why these elementary electrical principles are not taught in grade school. I feel they should be.

Cheers on a useful post!

Volts never has done a lick of work, but it can drive amps to do all sorts of mayhem!

 

[TemporaryKubotaOwnerMark]

People's resistance varies quite a bit, and sweat make a HUGE difference. 12v has stopped hearts. It's rare, but it has happened.

 

[CalG]

People's resistance varies quite a bit, and sweat make a HUGE difference. 12v has stopped hearts. It's rare, but it has happened.

I would like to read the report of a real event.
Words have little value. A quick search of the inter-web returns nothing...shocking! Urban myth?

Myself, I can't even feel 12V in any way, shape, or form (except on the tongue)

I think there is a warning label on my car battery to the effect of "Do not take internally" ......

 

[chim]

Still trying to wrap my head around getting your tongue across a car battery James. Pictures?

Now THAT would make Gene Simmons jealous

 

[POC]

I stepped on a residential entry line at a house fire last year. Lucky for me I had my gear on. But it sure popped and jumped and shot blue sparks. A couple of guys saw that I was going to step on it and were yelling at me, but a fire scene is a noisy place.