Whats the real killer, voltage or amperage?

I have always heard that the amount of amperage that a power supply could provide to a load, your body, was the real killer. But people on here are saying that under 50 volts is non-lethal.I have heard a story about a navy electrician who poked himself, under the skin, with a probe of a multimeter, to both of his thumbs on his hands, having them come in contact with his blood. When he turned it on to find the ohmage, the 9V Multimiter, fibrillated his heart, killing him. CNN reported that a milionth of an amp can kill you, 1 micro amp. If this is true, than why doesnt a tazer kill you? The barbs on a tazer rip in to the skin, making a complete circuit, just as the 9V Multimeter case. Whats the real deal here?

Reply to
Mr. J D
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I have been shocked by an Strobe ECAP that discharged 300 volts to me, the sensation I could describe as a thousand pins poking at me. If voltage was the real killer, than I should have been killed.

However, because of the resistance of my skin, my body did not assume much amperage. Doesnt thisd support the fact, that amperage is the killer and not voltage?

Reply to
Mr. J D

It depends on the path. If it's through your heart, 5 ma is enough.

Al

Reply to
Al

It is the current that can be delivered, not the voltage, that kills. The current will depend entirely on the conductivity/resistivity of your body. Your tongue is particularly conductive, hence the 'interesting' tingle on your tongue when you lick a 9V battery. For most people, voltages above 80 or so can become lethal if the source can supply 'unlimited' current.

Reply to
martin.shoebridge

And that's why smart guys keep one hand in their pocket when working with potentially lethal voltages.( TV's especially!)

Reply to
martin.shoebridge

Yes. not only that, but if to never touch a pontential voltage source with your palm. It is always best to touch with the nuckle side of the hand. By doing this, your hand wont contract and grip the wire.

Reply to
Mr. J D

Duh.

Reply to
Homer J Simpson

Urban legend. It didn't happen.

You believe CNN?

John

Reply to
John Larkin

I believe CNN more than Fox news. Now that is not to say that I found their story that mention 1 micro amp could kill you a little misleading.

Reply to
Mr. J D

CNN doesn't know a milliampere from a microampere, or a kilowatt from a kilowatt-hour.

John

Reply to
John Larkin

The question is misconceived -- sort of like "What do you need to breathe, air pressure or air flow?"

Voltage is a force, like pressure. It is the force that makes current flow. It can be present even when no current is flowing (like the pressure of compressed air in a tank when none of it is leaking out).

Voltage, when it meets conductance, causes current to flow. Current = amperage = zillions of electrons per second. (An amp is some huge, fixed number of electrons per second.)

We normally express conductance as resistance, which is its reciprocal:

Zero conductance = infinite resistance

Zero resistance = infinite conductance

In between, resistance is measured in ohms.

The human body has a certain resistance. Electric current flows through it in proportion to the voltage applied.

Current is the killer, *but* this current is *caused* by voltage.

That is:

Nothing happens to you if no current flows through your body.

Current cannot flow without a voltage to cause it.

If you connect your body to something with a high enough voltage, a significant current will flow. "High enough voltage" is usually reckoned as about 30 to 200 volts depending on how you make contact (e.g., dry skin vs. broken skin).

See? All this physics stuff (Ohm's Law) isn't just a dry abstraction. It is a vitally important description of how something works.

Reply to
mc

Now in more detail...

No. The amount of amperage that it CAN provide has NO effect unless it is actually providing it!

A power supply normally tries to put out a constant voltage, delivering as many amps as will flow through the load resistance.

Most power supplies will be damaged if the load has very low resistance and the power supply tries to deliver more amps than it safely can. That's what the "amperage it can provide" means.

Some power supplies have current limits and will simply decrease the voltage if they cannot maintain the normal voltage while delivering the amps demanded by Ohm's Law.

A few power supplies, such as neon sign transformers, have a high resistance built into the power supply to limit the current that will flow to a very small amount.

1 microamp can kill you if it flows directly through the heart muscle. Normally, lethal current is much larger, some tens of milliamps. The current from the Taser is limited to a very small amount.

Well, as I sometimes say to people I'm tutoring, "You can't understand it without understanding it." You can't think about volts and amps without knowing what they *are* and how they *work*. That's what the physics of Ohm's Law is all about. "Volt" and "amp" need to become more than just words to you.

Reply to
mc

If you test for voltage that way, My condolences - RIP.

Reply to
James Thompson

Typically. It's not voltage that's the killer though, it is indeed current.

That's why I included a caveat in my reply stating caution about contacting

*bare flesh* as opposed to skin. The resisitivity is very different.

Graham

Reply to
Eeyore

Would you mind asking your silly questions elsewhere ?

Graham

Reply to
Eeyore

Also don't wear rings.

Graham

Reply to
Eeyore

Some ppl believe Fox ! Far scarier !

Graham

Reply to
Eeyore

40 mA is where it starts getting dodgy.

Graham

Reply to
Eeyore

"There is more than one way to skin a cat!" a) To get your heart into fibrillation you need through it ~9V at about >=50uA and in such timing that it confuses the timing of nervous system. That's why you work with one hand in your pocket when near such systems. b) To "cook" you to crisp you need energy. As your body resistance decreases under the influence of voltage more and more current flows through it, so if the source can supply enough you become "well done" in few seconds.

Have fun

Stanislaw Slack user from Ulladulla.

Reply to
Stanislaw Flatto

Summing this up even more pointedly:

Volts and amps do not go around separately from each other. They are not two independent variables. One of them, along with resistance, is the cause of the other.

Reply to
mc

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