Somebody told me (regarding electricity) that it is the Amps that can kill you, not the Volts. Is this true?

Question

My boss disagrees with the above statement and says it is the other way round.

Answer 1

It's absolutely correct. Static electricity is thousands and thousands and thousands of volts, but virtually no current; it's quite harmless (unless there are flammable vapours in the air, which it can ignite). On the other hand, a large current of several amperes with only a few volts driving it can easily stop your heart. Current is the dangerous component; if it's present in large quantities then voltage can make it more dangerous. But voltage without significant current is harmless.

Answer 2

The current is indeed the killer. Above 30 milliamps is considered dangerous. Voltage is not a killer. Look at a neon tester screwdriver. You get 110 or 240 Volts through your body but you can't even feel it.

In old days when TVs needed 25 kilovolts to run a guy did a demo in the workshop. He disconnected and held the end of the high tension lead. Then got somebody to switch on the TV. Nothing happened to him. The trick was not to touch anything else at the same time otherwise you get a fat blue spark which would be painful but not deadly.

Answer 3

To properly understand this issue you have to delve somewhat into electrical engineering. I will call this concept "overwhelming". If a runner can run 20MPH does that mean he can grab a train and push it 20MPH. Also if you have a compressed tank of gas at 2000psi and then release the gas will it pressurize the earth to that pressure? To an extent the runner can carry something 20MPH and to an extent the tank can pressurize something. When we touch a source of electricity, our bodies determine the ratio of volts to amps. They both go up together. It is true that about .01 amp can kill. If your hands are dry, it will take about 200V to push that .01 amp through your body. If your hands are moist it may only take 50V to get that .01 amp. A shock source must be able to supply both the volts and amps (pressure and speed) without getting overwhelmed. A static spark is overwhelmed because it can't supply the amps. A car battery is overwhelmed because it can't supply the volts. Anyway they work together. You can't talk about one without the other in regards to electrocution.

Answer 4

It is all to do with the amount of charge passing through your body. This means that it is the current that ultimately kills you. Ohms law requires a minimum voltage for a given resistance to produce such a current. However a large potential difference (voltage) can be created, without sufficient ability to generate the necessary current.

As other have said, it all depends on how the current passes through the body. It takes a few tens of milliamps to stop your heart, but significantly more to do damage the other organs enough to kill you. That's why some people survive lightning strikes, which involve massive voltages.

Answer 5

Hi Cheeky,
Another word with your boss may be in order.
You are correct in what you say.
Alternating current and direct current have different effects upon the mortal frame, but in general, it is the value of the current (flow-rate) that creates mischeif with muscles, especially the heart & brain.
The potential difference, or voltage across said bodily parts is not necessarily the killer factor.
I have received a 33kV belt between shoulder & feet, and was only seeing stars for an hour or two.
Conversley, I had a 415V touch on a circuit carrying 800A, which laid me flat for a couple of days. Most alarming at the time.

It also depends on how you form the circuit.
Hand to hand, across the chest is not good.
One hand to earthed feet is not desirable, but far less dangerous to the system.

So it is indeed the amount of current, and less the amount of voltage that present the problem.

The National grids operate at high tension, and therefore relatively low current, for a variety of reasons such as lightweight conductor sizing, and also to keep high currents away from buildings, trees, etc.

Perhaps ask your boss to put his toung across the terminals of a PP3 9Vdc battery, and feel the tingle. That's current in a small dose.
It is only 9V, (and a good way of checking one without a meter to hand.)

Stick to your assumption, and keep away from stuff with lots of Amperes flowing down it !

Bob

Answer 6

Amperes are the killers. Amps measure the amount of electricity flowing through a conductor.
Voltage measures the 'force' or ability to overcome resistance.
The product of the two is wattage, or the amount of electrical power.
A static shock, when walking across carpet wearing socks, can be as high as 50,000 volts. However, the amperage, or current in extremely low.
Only 10 milliAmps (mA) across the heart can result in death.

Answer 7

Volts are the measure of 'pressure', if we use the water flow analogy, and Amps are the measure of 'rate of flow'. So a high pressure of water will not harm you if the flow is small eg. a child's water pistol . But if you upscale the water pistol to a firehose, then the potential for damage is greater. Same with electricity. You can hold a car spark plug lead, which is thousands of volts, but small amps, and will just get a mild shock, but if you hold onto a 240 volt household wire, passing say 15 amps, you will likely die.

Answer 8

By now you should be aware that it is the amount of electricity running through you that kills you.

Current flowing through you = electrons flowing through you.

Lots of electrons flowing through you = death.

Now look at your old rule V=I/R.
(V is voltage in volts, I is current in amps, R is resistance in ohms).

You are a resistor, so is everything that is not a superconductor.

Lots of electrons to run through you means lots of amps.

To get sufficient amps to flow you need sufficient voltage to overcome the resistance in the circuit.

You are part of the circuit - think where the electricity is flowing from and to.

The actual amount of current which will kill you if it runs through you is very small, less than one amp, however because the human body is of high resistance you need a high voltage to get even a small current running through you.

Hence it is the tiny "amps" that kill you, but they can only be pushed through your high resistance body if the "volts" are high.

Think of it like a metal spike being pushed into your chest.

Is it the thickness of the spike (like current), or is it how hard the spike is pushed in (like voltage) which kills you?

If the spike is microscopically thin (like small current), no matter how hard you push it (like high volts), it can pass through you without killing you.

Answer 9

It is the ammount of current flowing through you that kills you.

Your Boss has a point only in that the the higher the voltage, the more current will flow through you.

I have heard as little as 10 mA can kill, but this seems to be very misleading, since it will only kill you if it is passed directly through the heart itself.

60 mA passing through the body seems to be the most common figure quoted as being potentialy lethal though for AC.

The confusion seems to arise from higher voltages being more lethal. This is NOT because it is the voltage that will kill you, but that a higher voltage will allow more current to flow through you.

For example, I have often grabbed the "business end" of a -50KV
mains-powered air ionizer. You get a bit of a "tingle" from it, that is all, because the ouput voltage has to go through a 1000 Mohm resistor first and this limits the current to a very low level.

I hope this helps?!

Answer 10

Volts represent a difference in the potential energy of charged particles. Because of the Earth's composition there actually exists a difference in potential between your head and your feet, but you are still alive!
If the voltage causes electrons to move, creating a flow (in Amps) then you could get burnt.