Volts vs Amps

Strathead

Senior Member
And no current is going to pass if there is not enough voltage to drive it.
And there isn't going to be any voltage unless there are transmission lines, and there aren't going to be any transmission lines if there isn't a generator and there isn't going to be a generator without fuel. So I guess by your and iWire's thinking, fuel is what actually electrocutes people.

I don't care if there wouldn't be current flow if there wasn't voltage potential to allow the flow. It is still and always will be current flow that electrocutes people.
 
And there isn't going to be any voltage unless there are transmission lines, and there aren't going to be any transmission lines if there isn't a generator and there isn't going to be a generator without fuel. So I guess by your and iWire's thinking, fuel is what actually electrocutes people.

I don't care if there wouldn't be current flow if there wasn't voltage potential to allow the flow. It is still and always will be current flow that electrocutes people.

I love it!

I was going to post something like a fatal gunshot wound being caused by the powder in the gun and not the bullet, but your analogy is better.
 
Think about the bird on the wire.

The bird can be at a voltage level of thousands of volts, but he is OK. He can be 1,000's of volts above or below the earth, the next wire over, or the moon for that matter.

He will be just fine until he does something that causes current to flow through his body. Then, no more bird.

All those years being at 4,160 volts without so much as a rash. Then he gets a bit to big for his britches and takes 900 mA from wing to wing.

What killed him? the 900 mA, or the 4,160 volts?
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Think about the bird on the wire.

The bird can be at a voltage level of thousands of volts, but he is OK. He can be 1,000's of volts above or below the earth, the next wire over, or the moon for that matter.

He will be just fine until he does something that causes current to flow through his body. Then, no more bird.

All those years being at 4,160 volts without so much as a rash. Then he gets a bit to big for his britches and takes 900 mA from wing to wing.

What killed him? the 900 mA, or the 4,160 volts?
The bird is not experiencing 4160V, he is experiencing virtually 0V. In order to have voltage there must be a potential difference between two points. The voltage drop in the line he is standing on between the points where his feet touch the wire is the voltage he is experiencing, which isn't much.

This is a silly argument. Voltage and current/amperage are mathematical models constructed by humans to describe a physical phenomenon. They do not exist as separate entities; it is only us who separate them so that we can do math on them.
 
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iwire

Moderator
Staff member
Location
Massachusetts
So you think that a given amount of watts is fatal through a path (for instance trough the heart) is going to be a fixed value no matter what the voltage or current is?

If that were the case, .001 amps at 2,000 volts would be as dangerous as .1 amps at 200 volts. Both are 20 watts.
No, that is not what I said, the needed watts will of course change dependent on circuit characteristics.

But no death will happen without voltage.

No death will happen without current

Therefore it takes power to produce the work of damaging the body.
 

iwire

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Staff member
Location
Massachusetts
And there isn't going to be any voltage unless there are transmission lines, and there aren't going to be any transmission lines if there isn't a generator and there isn't going to be a generator without fuel. So I guess by your and iWire's thinking, fuel is what actually electrocutes people.
Then you have not been reading the thread


I don't care if there wouldn't be current flow if there wasn't voltage potential to allow the flow. It is still and always will be current flow that electrocutes people.
False.
 
The bird is not experiencing 4160V, he is experiencing virtually 0V. In order to have voltage there must be a potential difference between two points. The voltage drop in the line he is standing on between the points where his feet touch the wire is the voltage he is experiencing, which isn't much.

This is a silly argument. Voltage and current/amperage are mathematical models constructed by humans to describe a physical phenomenon. They do not exist as separate entities; it is only us who separate them so that we can do math on them.
Voltage is not 'experienced'. It is a value of a difference between two points. It's current that is 'experienced'. The bird may be at 0 volts referenced to the wire he is sitting on, but he will be at (for example) 4,160 from the next phase conductor. He may also be a couple hundred thousand volts compared to an HV line running near him. The point is, voltage is a value of comparison, not a constituent of effect.

That is why levels of threshold for shock, fatalities, etc., are expressed in amperes. Milliamperes, usually.

Those levels, threshold values, are the levels of what is 'experienced' and are not measured in volts. Those values are pretty much fixed values. Both voltage and power can vary wildly, but it's only the current that has to be guarded against. Otherwise threshold values would be expressed in volts or watts. They are not, hopefully as you know.
 

iwire

Moderator
Staff member
Location
Massachusetts
Think about the bird on the wire.

The bird can be at a voltage level of thousands of volts, but he is OK. He can be 1,000's of volts above or below the earth, the next wire over, or the moon for that matter.

He will be just fine until he does something that causes current to flow through his body. Then, no more bird.

All those years being at 4,160 volts without so much as a rash. Then he gets a bit to big for his britches and takes 900 mA from wing to wing.

What killed him? the 900 mA, or the 4,160 volts?
The power of provided by volts and amps together.
 

iwire

Moderator
Staff member
Location
Massachusetts
Voltage is not 'experienced'. It is a value of a difference between two points. It's current that is 'experienced'. The bird may be at 0 volts referenced to the wire he is sitting on, but he will be at (for example) 4,160 from the next phase conductor. He may also be a couple hundred thousand volts compared to an HV line running near him. The point is, voltage is a value of comparison, not a constituent of effect.

That is why levels of threshold for shock, fatalities, etc., are expressed in amperes. Milliamperes, usually.

Those levels, threshold values, are the levels of what is 'experienced' and are not measured in volts. Those values are pretty much fixed values. Both voltage and power can vary wildly, but it's only the current that has to be guarded against. Otherwise threshold values would be expressed in volts or watts. They are not, hopefully as you know.
You show me any electrical work done by current alone and you might make some progress.
 
And there isn't going to be any voltage unless there are transmission lines, and there aren't going to be any transmission lines if there isn't a generator and there isn't going to be a generator without fuel. So I guess by your and iWire's thinking, fuel is what actually electrocutes people.

I don't care if there wouldn't be current flow if there wasn't voltage potential to allow the flow. It is still and always will be current flow that electrocutes people.
No that's not what I'm saying. A tiny bit of current is all it takes to kill you. Less than one amp across your heart and your dead if your in surgery, a few more amps to cook you if you have a hold of a live wire bare handed, but it's the voltage that gets it there. It takes both enough current at a high enough voltage level, depending on the circumstances, to cause injury.
 

GoldDigger

Moderator
Staff member
No that's not what I'm saying. A tiny bit of current is all it takes to kill you. Less than one amp across your heart and your dead if your in surgery, a few more amps to cook you if you have a hold of a live wire bare handed, but it's the voltage that gets it there. It takes both enough current at a high enough voltage level, depending on the circumstances, to cause injury.
And internally it is the voltage difference between two points in the body that causes the problems with nerves firing. The current has to flow through an area of the body where the nerve operation is critical.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
And internally it is the voltage difference between two points in the body that causes the problems with nerves firing. The current has to flow through an area of the body where the nerve operation is critical.
I'll say it again: this is a silly argument. Voltage and current are two humanly contrived aspects of the same physical phenomenon. They cannot exist separately. Voltage alone doesn't kill and current alone doesn't kill because neither exists in the absence of the other. Electricity kills.
 

iwire

Moderator
Staff member
Location
Massachusetts
I'll say it again: this is a silly argument. Voltage and current are two humanly contrived aspects of the same physical phenomenon. They cannot exist separately. Voltage doesn't kill, current doesn't kill, electricity kills.
:thumbsup:
 

charlie b

Moderator
Staff member
Location
Seattle, WA
Quoted from "Person One": "The sky is blue."
Quoted from "Person Two": "No, you are wrong. The grass is green."

For my part, I will continue to think of the phenomenon of electrocution in the following way:

  • It is the flow of current through the body that causes damage to cells (e.g., muscle or nerve cells) and that interferes with the function of internal organs (e.g., the heart).
  • It is a difference in potential (i.e., the voltage source) that forces current to flow through the body in opposition to the resistance of human tissue. This is where Ohm's Law comes into play.
  • The rate at which energy (in units of "joules per second," commonly known as watts) is dissipated within the body can be determined by multiplying the voltage (in units of "joules per coulomb," commonly known as volts) times the current (in units of "coulombs per second," commonly known as amps). This is a simple consequence of the definition of "power."
  • If any two of these parameters (i.e., watts, volts, and amps) are present, the third will be present as well.
 
I'll say it again: this is a silly argument. Voltage and current are two humanly contrived aspects of the same physical phenomenon. They cannot exist separately. Voltage alone doesn't kill and current alone doesn't kill because neither exists in the absence of the other. Electricity kills.
OK then, WHY are the threshold values always expressed in mA as opposed to volts or watts?

Is it because the authors of those values don't know what they are talking about? If you and Iwire's stance is indeed true, then why hasn't anyone else discovered this a long time ago and changed 'the books'?
 
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