>Quote from: Siwastaja on 2021-06-04, 21:58:19>Quote from: Quarlo Klobrigney on 2021-06-03, 21:34:22120V is irrelevant. It's the current that kills. The voltage just breaks the skin resistance to help kill you.
I wouldn't expect to read this bullshit on the EEVBlog forum...
Perhaps an apology to Quarlo K would be appropriate at this point?
Some people will never get it.
Quote from: dunkemhigh on 2021-06-05, 09:07:49>Quote from: Siwastaja on 2021-06-04, 21:58:19>Quote from: Quarlo Klobrigney on 2021-06-03, 21:34:22120V is irrelevant. It's the current that kills. The voltage just breaks the skin resistance to help kill you.
I wouldn't expect to read this bullshit on the EEVBlog forum...
Perhaps an apology to Quarlo K would be appropriate at this point?
I = V/R, so given the major impediment to dying is skin resistance, does not a higher voltage mitigate that skin resistance? Or are you just quibbling about the way a non-native English speaker has phrased it?
Well... The 2nd sentence, above, that I put in Bold, IS true!!, though the rest is crap...
It IS the 'Current' that kills!!!
Now grab hold of a 50-100 thousand volt Van-De-Graph
generator which has no ability to supply the 'current' necessary to be dangerous, then you can laugh at the sparks!!
Well... The 2nd sentence, above, that I put in Bold, IS true!!, though the rest is crap...
It IS the 'Current' that kills!!!
It's not though, since it's not a single factor. It's most reliable to say that exceeding a specific amount of energy is what can stop the heart - There are factors in both power and time. The human body could survive kiloamperes of current if the duration is short enough.Now grab hold of a 50-100 thousand volt Van-De-Graph
generator which has no ability to supply the 'current' necessary to be dangerous, then you can laugh at the sparks!!
Are you saying that somehow a Van de Graaff generator is somehow able to alter the laws of physics by somehow conducting only a tiny amount of current through a person despite a high voltage being present across them?
A Van de Graaff generator is a constant current source of a few µA. It outputs the same current, regardless of the open circuit voltage, up to a point, when the voltage is so high, it arcs over. If you put one hand on the dome and the other on the earthed side and turn it on, the open circuit voltage will be tiny and the current too low to shock. If you allow the dome to charge, the voltage will increase. If you discharge the dome into your finger, you'll get a shock, but it won't be dangerous, because the dome has too little capacitance, to store enough energy to be hazardous. If you connect it to a large capacitor and leave it running, it can deliver a lethal shock.
If it's "current that kills", then you may want to try to explain yourself how RCDs are able to save lives. Note, they can't limit current, it is what it is; they only limit the time.
No need to reply to me; I'm not interested in social games. I prefer intellectual honesty so work it out in your own head. It's not all that complex if you choose to ignore rules developed 100 years ago for explaining things to laymen using bad analogies. Instead, work with the basic units available to us scientists and engineers. Voltage, current, resistance, impedance, power, time, energy... For example, a high-impedance high-voltage supply forms a classic voltage divider with the body impedance, and the lower the body impedance, the lower the voltage over body. Think about all of this instead of playing social games.
If it's "current that kills", then you may want to try to explain yourself how RCDs are able to save lives. Note, they can't limit current, it is what it is; they only limit the time.
No need to reply to me; I'm not interested in social games. I prefer intellectual honesty so work it out in your own head. It's not all that complex if you choose to ignore rules developed 100 years ago for explaining things to laymen using bad analogies. Instead, work with the basic units available to us scientists and engineers. Voltage, current, resistance, impedance, power, time, energy... For example, a high-impedance high-voltage supply forms a classic voltage divider with the body impedance, and the lower the body impedance, the lower the voltage over body. Think about all of this instead of playing social games.It's pretty obvious time is a factor, as well as current. As mentioned above, a Van de Graaff generator discharging into someone might give a peak current of 50A, but it's such a short duration, it doesn't cause any damage.
my statement... It is not 'X' number of Volts that is the problem
120V is irrelevant. It's the current that kills. The voltage just breaks the skin resistance to help kill you.
I wouldn't expect to read this bullshit on the EEVBlog forum...
Voltage is what defines the current that flows through the (complex and nonlinear) impedance of the human being. That's exactly why all the safety regulations are based on voltage. Safety voltage / extra low voltage limit for 50/60Hz AC being roughly around 40-60V depending on the jurisdiction. See https://en.wikipedia.org/wiki/Extra-low_voltage
Anyway, comment about delayed arrhythmia is a good one. It's always a good idea to get checked if in doubt.
120V is irrelevant. It's the current that kills. The voltage just breaks the skin resistance to help kill you.
I wouldn't expect to read this bullshit on the EEVBlog forum...
Voltage is what defines the current that flows through the (complex and nonlinear) impedance of the human being. That's exactly why all the safety regulations are based on voltage. Safety voltage / extra low voltage limit for 50/60Hz AC being roughly around 40-60V depending on the jurisdiction. See https://en.wikipedia.org/wiki/Extra-low_voltage
Anyway, comment about delayed arrhythmia is a good one. It's always a good idea to get checked if in doubt.
He is correct in that it is the current that kills. But it is related to voltage of course, so 120V is not irrelevant.
Your comment reminded me of an argument I had with another engineer at the workplace lunchroom who thought he knew it all. OK, he had a PhD in electronics engineering and I only had the degree. But I knew what I was talking about. IBM Australia years earlier placed every engineer on an electrical safety course. I learnt then that 20mA through the body can easily kill a person by electrocution. The PhD refused to believe me that so low current can kill a person, saying it would take several hundred milliamps. You could not argue with this guy who was a little arrogant, but I refused to backdown. Unbeknown to me, he decided to research it for himself.
Two days later, in front of my peers at the lunchroom table, he apologised publicly, admitting he was wrong and I was right. It was a complete shock (no pun intended). From that day on, he was never argued or was arrogant with me again, and we ended up becoming good friends.
He is correct in that it is the current that kills. But it is related to voltage of course, so 120V is not irrelevant.
Your comment reminded me of an argument I had with another engineer at the workplace lunchroom who thought he knew it all. OK, he had a PhD in electronics engineering and I only had the degree. But I knew what I was talking about. IBM Australia years earlier placed every engineer on an electrical safety course. I learnt then that 20mA through the body can easily kill a person by electrocution. The PhD refused to believe me that so low current can kill a person, saying it would take several hundred milliamps. You could not argue with this guy who was a little arrogant, but I refused to backdown. Unbeknown to me, he decided to research it for himself.
I'm also surprised people take calling "bullshit" "bullshit" so personally
given that this B word is so prevalent on this forum and on Dave's videos
I'm also surprised people take calling "bullshit" "bullshit" so personally given that this B word is so prevalent on this forum and on Dave's videos, but I may have missed some social factor I'm not too good in, maybe it's OK to call bullshit when it's about an outsider's video, or a post by some of the lower-class members, but I'm not aware of Quarlo's social status because I have no idea who he is and what he contributes here, so clearly I hit the wrong button here. This is why I said I don't like these social games.
...
to see why safety limits are primarily given in voltages, not currents.
Ohm's law connect the two together so it's makes zero sense to argue "which is dangerous", they are different ways to look at the same thing, namely energy transfer. Current and voltage are just tied together, if there is dangerous voltage applied to a human body, there is dangerous current flowing, and vice versa. So you choose current or voltage viewpoint depending on which is the suitable tool for the task. Voltage limitation (of the voltage source), or current limitation (of the current source) ensures safety the easy way - i.e., use Safety Extra Low Voltage - but isn't always an option.
QuoteI'm also surprised people take calling "bullshit" "bullshit" so personally
That, there, is the problem. If you'd just pop up and say no, that's not correct because...", then you'd have an audience listening to your argument and being enlightened. By making it personal and derogatory you lost all that before you even said what was wrong.Quotegiven that this B word is so prevalent on this forum and on Dave's videos
Just because someone safe behind a screen has no manners, you don't have to emulate them.
There is a reason why 30mA is a popular choice for RCDs, it gives very good (albeit not perfect, but nothing is) defence against death by electrocution