What would be an intelligent responce?

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pfalcon

Senior Member
Location
Indiana
It's the bullets that kill ya, but it's real tough ta shoot yerself without a gun. Voltage is the gun.

Damage derives from power I*I*R but the R that counts is a constant so I is proportional to E (E=I*R). Once the voltage overcomes the resistance then current rises with voltage.
 

iwire

Moderator
Staff member
Location
Massachusetts
This question is always presented as an either / or type issue and IMO it is not either / or it is both.

You can have voltage without current, you can't have current without voltage. So like the gun example you need both in the right combination to kill you.

So I will stick with it is electricity that kills, not exclusively the voltage or exclusively the current.
 

Hendrix

Senior Member
Location
New England
This question is always presented as an either / or type issue and IMO it is not either / or it is both.

You can have voltage without current, you can't have current without voltage. So like the gun example you need both in the right combination to kill you.

So I will stick with it is electricity that kills, not exclusively the voltage or exclusively the current.

I like that:happyyes:
 

bphgravity

Senior Member
Location
Florida
I believe there are actually 5 dimensions to the equations. One aspect that is frequently not considered is TIME. It is true that voltage, amperes, and resistance are the electrical factors but it is the exposure over time that injures and kills you. The 5th factor is your biology (age, gender, health, etc.)

For example, the lethal time of exposure to electricity can be expressed as Seconds = .116 / (E/R). Using that formula, a typical person can be exposed to a 120V shock for only 1 second or 60 cycles. That same person can only be exposed to a 277V shock for .42 seconds or 25 cycles. A person that is ill or elderly would not survive even shorter exposures.

You may also want to keep in mind that while there are likely 30,000 or more electrical shocks a year in the US, the greatest majority of electrical injuries requiring hospital stay are a result of arc-flash / blast. Just some food for thought...
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
It aint the voltage, it's the amps that kills ya.


Stick your tongue on a 9 volt battery, then stick your tongue in a 120 volt light socket. Now tell me that the voltage doesn't matter. :roll:

Not picking on you, but if you're going to use intelligent response in a sentence then you need to spell response correctly.
 

Hendrix

Senior Member
Location
New England
Stick your tongue on a 9 volt battery, then stick your tongue in a 120 volt light socket. Now tell me that the voltage doesn't matter. :roll:

Not picking on you, but if you're going to use intelligent response in a sentence then you need to spell response correctly.

I guess I should really get spell check :weeping:
 

Barndog

Senior Member
Location
Spring Creek Pa
Stick your tongue on a 9 volt battery, then stick your tongue in a 120 volt light socket. Now tell me that the voltage doesn't matter. :roll:

Not picking on you, but if you're going to use intelligent response in a sentence then you need to spell response correctly.

Yes voltage does matter. But is is the Current that the voltage is pushing through your body that kills you.
With resistance being constant current is directly proportional to the applied voltage.
 

big john

Senior Member
Location
Portland, ME
While it may be technically correct that the amperage does the damage, I think it's splitting hairs.

Every power system in every building is capable of supplying enough amperage to kill you, so is it really relevant when trying to figure out the risk involved? The only thing that changes is the voltage level, so the voltage is what people should pay attention to.

-John
 

yankj

Senior Member
Yes voltage does matter. But is is the Current that the voltage is pushing through your body that kills you.
With resistance being constant current is directly proportional to the applied voltage.

Yes, yes, yes! Very well stated. Voltage is the driving force. Current is the flow of electrons.
 

pfalcon

Senior Member
Location
Indiana
Um, strictly speaking, neither Voltage nor Current kills.

E/R calculates I

I*I*R calculates power

Current does not kill because: For a given current, if you can reduce the resistance then you lower the damage.

Actual causes of death are typically: (1) Excessive power delivered in the form of HEAT thereby destroying the tissue and (2) electrical interference with the sychronization of the heart.

But then: If you don't have the gun (voltage) or the bullet (muzzle velocity) then you can't deliver the horsepower (heat) to the target.
 

rich000

Senior Member
Would you touch a 25,000V system, what about a 100,000V system?

A Van de Graaff generator can put out about 100,000V or more. A Taser about 25,000V. However, both of these devices are constant current (low current at that).

It's the current that kills you.
 
This question is always presented as an either / or type issue and IMO it is not either / or it is both.

You can have voltage without current, you can't have current without voltage. So like the gun example you need both in the right combination to kill you.

So I will stick with it is electricity that kills, not exclusively the voltage or exclusively the current.

Precisely, to use your gun analogy, it is not(just) the projectile that kills you but explosive charge's quantity that propells the projectile to the velocity that delivers the kinetik force. In other words, if the charge is so small that it just pushes down the slug in the barrel and it just drops out of it, it certainly isn't going to kill you.

Conversely if the voltage is small, it not only won't kill you, but you can't even feel it. So it can be said that it is the voltage that will determinel the level of danger, conversely it is voltage that kills you. This would be a logicly sound reasoning.
 

jwelectric

Senior Member
Location
North Carolina
When I was in high school I was involved in an experiment where I let around 20,000 volts conduct over my body. This voltage was introduced to my body not once but several times in that one 55 minute class. This voltage was at a very high frequency and the event would last for several seconds at a time.
I did not die.

Every piece of training material I have ever seen only mentions amperage when it comes to the effect of current on the human body. Every one of them states that death can occur at around 100 milliamps but none of them mentions at what voltage.

A Tesla coil was used to introduce a very high voltage to my body with no ill effects then it is obvious that a high voltage can be introduced to the human body with no ill effects.

Electron flow (current/amperage) on the other hand only needs to be minute in order to cause damage to the human body at any voltage.

Using the information above one could discern that it is current that causes ill effects on the human body and not the voltage making the statement, ?current kills not voltage? a true statement.

Granted the amount of pressure pushing (voltage) the current through the resistance of the human body plays a role in the amount of current flowing it is still the electron flow (current) that causes the ill effects. Once current is flowing through the body the resistance of the body drops over time at an exponential rate causing the current to become higher as the voltage remains constant.

Knowing these facts I teach the statement that current kills. I also use a ground fault interrupter device to back my statement. These devices must open between 4 and 6 milliamps not between 110 and 130 volts.
 

iwire

Moderator
Staff member
Location
Massachusetts
Using the information above one could discern that it is current that causes ill effects on the human body and not the voltage making the statement, ?current kills not voltage? a true statement.

It is not an untrue statement but it is hardly a complete statement.

It is voltage, it is current, it is time as Brian pointed out and I bet other factors as well.


Again it is not an either / or type question.
 
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