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persia7
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in welding operation , you never hit by electric shock,why?
persia7 said:in welding operation , you never hit by electric shock,why?
persia7 said:what is voltage need to get electric shock?
FeynmanIsCool said:Depends on Amps. Its the amps that will most likely harm you.
Here's an analogy
Lets say voltage is a baseball, and Amperage is how fast the baseball is moving. If you have a baseball (lets say 120v) but low amperage (lets say the ball is just tossed in the air), its not going to do much damage to you if it hits you(may do a little). BUT if that 120v has HIGH amperage, its like that same baseball coming at you at 100mph, and that's going to hurt! That's why they say its the amps that get you, not the voltage. (its kinda like kinetic energy is to the baseball, as amps are to voltage in a loose sense)
This is not true at all. Voltage alone decides the deadlines since current does not play a real role in dielectric breakdown. The Ohm's law cannot be used: if I touch the +12V rail of my PC's power supply while grounded nothing will happen although it is rated for 15A. Even 600A at several volts can't possibly do any damage. Now if I touch a CFL rated at 40mA while connected to mains a lot will happen and I could die.davenn said:not entirely correct
even a small voltage and current can cause a good tingle, think of a 9 V battery on the tongue or other damp area.
on skin the combination of voltage and current only need to over come your skin resistance to give you a shock. It only takes 30mA through the chest to put the heart into fibrilation.
the old saying is ... Volts Jolts, Current Kills
cheers
Dave
Cyclix said:This is not true at all. Voltage alone decides the deadlines since current does not play a real role in dielectric breakdown. The Ohm's law cannot be used: if I touch the +12V rail of my PC's power supply while grounded nothing will happen although it is rated for 15A. Even 600A at several volts can't possibly do any damage. Now if I touch a CFL rated at 40mA while connected to mains a lot will happen and I could die.
Low voltage high current is inherently safer than high voltage low current. That is why safety equipment for living things is rated for voltage and not amps.
Cyclix said:This is not true at all. Voltage alone decides the deadlines since current does not play a real role in dielectric breakdown. The Ohm's law cannot be used: if I touch the +12V rail of my PC's power supply while grounded nothing will happen although it is rated for 15A. Even 600A at several volts can't possibly do any damage. Now if I touch a CFL rated at 40mA while connected to mains a lot will happen and I could die.
Low voltage high current is inherently safer than high voltage low current. That is why safety equipment for living things is rated for voltage and not amps.
Exactly. So it's voltage alone that decides whether that fixed puny amount of current flows. Lower voltage: it won't flow. Higher voltage: it will flow. The source itself could supply 90mA or 543624A - if the voltage is not high enough, nothing will happen. 20 V across the hands can't push those deadly 90mA. 0.2 V across the heart can't push those deadly 90mA.Averagesupernova said:Please don't post garbage like this. Now it is unlikely that several volts from one hand to the other will be able to push 600 amps through, but it is in fact current that kills. How many volts do you think it would take to push the amount of required current to kill through the heart from an open chest wound? The volts that it takes to kill depends on conditions of the body and points of contact. The current through the heart it takes to kill is pretty much constant.
They will shock you pretty severely if you touch the output of the transformer that's inside. You should not assume that all things suitable for sitting on desks are safe.FeynmanIsCool said:what?? this is completely false. If this was true then the harmless "plasma orbs" (jim hardy's comment) that sit on peoples desk tops would severely shock you.
If the hands have been wet for a while so there is very good conduction to deep tissue significant current can flow.
jim hardy said:And you "get the feel" of current stimulating your nerves.
old jim
Averagesupernova said:Cyclix, I don't understand how you don't understand. Just as I posted and you somewhat agree the amount of current through the heart that it takes to kill does not change much. The amount of voltage it takes to do this varies widely on conditions of the body. We were told in school that even what is considered safe voltages (50 volts and less) can cause death when placed from hand to hand. If the hands have been wet for a while so there is very good conduction to deep tissue significant current can flow.
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I AM adjusting voltage. Pay attention already. Jim Hardy gave a pretty good example of how it happens at 12 volts. And I said:The amount of voltage it takes to do this varies widely on conditions of the body.Cyclix said:There is a fallacy in this argumentation. You are involving variable resistance in the equation but not adjusting the other important parameter (voltage) at the same rate.
Is the above an attempt to disagree with me? It is in fact agreeing with what I am saying. I'll say it again: Voltage that it takes to injure/kill varies with body resistance. Halve the resistance and halving the voltage will accomplish the same thing. The current will not change.If we lower the voltage with the same factor as the resistance we will see again that if the input voltage is not enough to push our given dangerous current, nothing happens.
The power supply itself could be rated for 1000s of A but if its voltage is below a certain threshold for a given resistance then nothing will happen. The only way for some living thing to get harmed in this setup is by increasing the voltage.
Next time you hear "Amps kill you, Volts don't" ask that person what would he rather touch, 15A at 12V or 40mA at mains voltage. The latter supplies hundreds of times less "amps". Just don't let them try to disprove me by experiment.
Cyclix said:There is a fallacy in this argumentation. You are involving variable resistance in the equation but not adjusting the other important parameter (voltage) at the same rate. If we lower the voltage with the same factor as the resistance we will see again that if the input voltage is not enough to push our given dangerous current, nothing happens. The power supply itself could be rated for 1000s of A but if its voltage is below a certain threshold for a given resistance then nothing will happen. The only way for some living thing to get harmed in this setup is by increasing the voltage.
Next time you hear "Amps kill you, Volts don't" ask that person what would he rather touch, 15A at 12V or 40mA at mains voltage. The latter supplies hundreds of times less "amps". Just don't let them try to disprove me by experiment.
And there you have it, increase the voltage, the danger goes up. Conversely, you can't increase the supplied current and somehow expect that it starts flowing where it didn't flow before. So given a non dangerous live circuit and a grounded organism touching it, we can only make it dangerous by increasing the voltage. In such a scenario the quote "it's not the voltage, it's the amps that get you" is just plain absurd since ramping up the volts is what WILL get you. :)sophiecentaur said:Those are meaningless figures. The current flow depends upon the applied volts and the (possibly non-linear) resistance of a load (in conjunction with with the source resistance).
Yes adherents of the not-the-voltage-but-the-amps theory start to say these things sooner or later. If you look at similar discussions you will even see people who claim to have been struck by lightnings & stuff and nothing happened since 'it's not the volts'... Unverifiable claims at best.Averagesupernova said:Oh yeah, given the question about a 12 volt 15 amp supply vs. 120 volt .04 amp supply. I've been across 120 volts hand to hand with virtually no sensation. Obviously my hands were dry and due to no sensation many times less than .04 amps in my body. I've also been across 12 volts with wet hands and a VERY noticeable current flowing but I can assure you it was nowhere near .04 amps to say nothing of 15 amps. Do you see what I mean yet?
Cyclix said:....
3. Whoever thinks that a low current high voltage system is safer than a high current low voltage system is most likely neither an electrical engineer nor a physician, never asked himself why instruments and installations are safety rated for volts and not amps, and why there are placards saying "danger! high voltage" and none with "danger! high amperage".
I mean I can only try so hard
Not sure what you are saying here. It really makes no sense. Are you saying that increasing available current will not make it flow where it wasn't flowing?Conversely, you can't increase the supplied current and somehow expect that it starts flowing where it didn't flow before.
Ohms law tells us that if we do not change the voltage and wish to change the current the only thing we can do is to lower the resistance. In this case that would equate to wetting the hands. The converse is true of course which you have been arguing all along No problem with increasing voltage to increase the amount of current as long as the source is able to supply the current. YOU seem to be the one getting current and voltage confused here.So given a non dangerous live circuit and a grounded organism touching it, we can only make it dangerous by increasing the voltage.
So will wetting the hands.In such a scenario the quote "it's not the voltage, it's the amps that get you" is just plain absurd since ramping up the volts is what WILL get you. :)
Averagesupernova said:...In old CRT type televisions high voltages existed in many places. Voltages as high as 30,000 volts were present. Guess what was generally considered the most dangerous voltage in the TV set? It was the 120 volt line voltage. The only reason other voltages were considered dangerous was because when you got hit with one your arm would jerk out of the set so quickly that you would likely cut yourself on part of the chassis. So cyclix, have you worked on a lot of CRT type televisions?
Nope I haven't done that at all. But I can still tell you why the mains voltage had to be considered the most dangerous one :)Averagesupernova said:In old CRT type televisions high voltages existed in many places. Voltages as high as 30,000 volts were present. Guess what was generally considered the most dangerous voltage in the TV set? It was the 120 volt line voltage. The only reason other voltages were considered dangerous was because when you got hit with one your arm would jerk out of the set so quickly that you would likely cut yourself on part of the chassis. So cyclix, have you worked on a lot of CRT type televisions?
The presence of moisture on the skin, such as wet hands, can significantly increase the conductivity of the human body. This means that electrical current can flow more easily through the body, increasing the risk of electric shock.
Moisture acts as a conductor, allowing electrical current to flow more easily through the body. This is because water contains ions (charged particles) that can help carry the current through the body.
Electric shock can cause serious injuries, such as burns, muscle contractions, and even cardiac arrest. In some cases, it can be fatal. In addition, the shock can cause the person to lose control and potentially harm themselves or others in the vicinity.
To reduce the risk of electric shock, it is important to follow safety protocols, such as wearing appropriate protective gear and using well-maintained equipment. It is also crucial to ensure that the area is dry and free of any moisture to prevent conductivity.
Yes, other factors that can increase the risk of electric shock include working in a confined space, working with equipment that is not properly grounded, and using damaged or faulty equipment. It is important to always be aware of potential hazards and take necessary precautions to prevent electric shock.