"It's not the volts, it's the amps that kill you."

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JFletcher

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Williamsburg, VA
At 0:51, they confirm it. I like literal. heh.

Yes, it takes both, which is why a static shock or taser (high volts, low amps) nor a truck battery (low volts, high amps) are likely to kill you. It also takes a hit across the heart or enough damage otherwise to kill you. There's hundreds of videos of people playing with Van de Graaff generators, but none of people playing in 4160V MCCs.
 

GoldDigger

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At 0:51, they confirm it. I like literal. heh.

Yes, it takes both, which is why a static shock or taser (high volts, low amps) nor a truck battery (low volts, high amps) are unlikely to kill you. It also takes a hit across the heart or enough damage otherwise to kill you. There's hundreds of videos of people playing with Van de Graaff generators, but none of people playing in 4160V MCCs.

The "truth" of that adage depends on how you interpret it.
If you are talking about the source voltage and the available source current, then it certainly needs both. And I suspect this is the way most people interpret it.
But if you look at the current through your body, for a specific path, it is exactly the current that kills you, and the voltage will be whatever it takes to produce that current.
 

Carultch

Senior Member
Location
Massachusetts
For those that (unfortunately) believe this old chestnut, here is what I think is a well done video treatise on the subject.

https://www.youtube.com/watch?v=8xONZcBJh5A


The reason why people say this "old chestnut", is to establish that it isn't absolute voltage that does any damage. It is when relative voltage differences across your body causes charges to flow, that causes damage.

Having your entire body in contact with an identical absolute voltage, no matter how high it may be, makes you a "bird on the wire", and therefore safe.
 

don_resqcapt19

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Illinois
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retired electrician
The "truth" of that adage depends on how you interpret it.
If you are talking about the source voltage and the available source current, then it certainly needs both. And I suspect this is the way most people interpret it.
But if you look at the current through your body, for a specific path, it is exactly the current that kills you, and the voltage will be whatever it takes to produce that current.
That is backwards...the source voltage and the resistance of the path through the body will determine the current.

As far as what kills you...you can't have one with out the other:)
 

GoldDigger

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That is backwards...the source voltage and the resistance of the path through the body will determine the current.

As far as what kills you...you can't have one with out the other:)
That is exactly what I was saying. You specify the current that will kill you and then the voltage that will kill you is that current times your body resistance.
 

winnie

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Location
Springfield, MA, USA
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Electric motor research
Oh the equine necrobattery.

I agree that this video is a good presentation of the subject, both because it goes into the fact that voltage is necessary for injury and because it shows (and mentions) the safety table given in current levels.

The severity of injury appears to depend on _current_. That is the reasonable basis for 'its the amps that kill'. Clearly there _must_ be something to push that current to cause the injury. But how much voltage will depend on the specifics of how the circuit is connected to the body. It doesn't matter if it is 30V or 300V, if you get 100mA through your heart you are not going to have a good day.

-Jon
 

donaldelectrician

Senior Member
If the electricity enter the body through a Puncture Wound , the skin resistance will decrease and you will be shocked more

severely .


The outer skin is more dead .




Don
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
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Electrician
If the electricity enter the body through a Puncture Wound , the skin resistance will decrease and you will be shocked more

severely .


The outer skin is more dead .




Don

It's not that the skin is dead.

Your skin is dry compared to the tissue underneath it. It acts like a resistor. Under the skin, especially in the blood, is mostly water with salt in it, which conducts electricity much better than dry skin.
 

JFletcher

Senior Member
Location
Williamsburg, VA
It's not that the skin is dead.

Your skin is dry compared to the tissue underneath it. It acts like a resistor. Under the skin, especially in the blood, is mostly water with salt in it, which conducts electricity much better than dry skin.

Which explains why getting hit in July in a 150* attic (sweating, salty) is considerably more sucky than getting a light tingle when you are dry.

Forget death tho for a moment; I wonder how many injuries are caused by jerking away from electric shocks than the shocks themselves. Last time I got nailed good was working 15' up on a ladder on a MWBC that I didnt recognize as such. Grabbed the neutral, it grabbed me. To this day I dont know how I didnt come off that ladder, since I was well grounded on building steel.

the thread title reminds me of another addage: "Assumption is the mother of all foul-ups"
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
Which explains why getting hit in July in a 150* attic (sweating, salty) is considerably more sucky than getting a light tingle when you are dry.

Forget death tho for a moment; I wonder how many injuries are caused by jerking away from electric shocks than the shocks themselves. Last time I got nailed good was working 15' up on a ladder on a MWBC that I didnt recognize as such. Grabbed the neutral, it grabbed me. To this day I dont know how I didnt come off that ladder, since I was well grounded on building steel.

the thread title reminds me of another addage: "Assumption is the mother of all foul-ups"

The very first president of the IBEW was killed from a ladder fall after he got shocked. The shock wasn't fatal, the fall was.

So, as you can imagine, I was taught in my apprenticeship that the reaction from a shock can be as bad or worse than the shock itself.
 
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