3 ms·

Today I learnt that pure water is not conductive and than tap water is a poor conductor at 120V which I believe is the american standard... What about Europe's

Today I learnt that pure water is not conductive and than tap water is a poor conductor at 120V which I believe is the american standard... What about Europe's 230V ? Would he still have gone in the water to unplug the piano if he was in Europe ?

Spellman 2y ago
Luckily we have equations for this! Assume that the water has a fixed resistance of R. You have increased the Voltage V about double. As a result of V=IR, the I, or current flow, will be doubled. Which in this case is probably a moderate tingle since R is so high. For reference, the heart muscles start getting involuntary twitches around 100mA, and at 200mA causes cardiac arrest. And the standard units of Voltage, Amp, and Ohm will serve you well here for any conversions.
- pvillano 2y ago
  You'll get the same tingle at a greater distance. In fact, if the current is finite and current density decreases with distance, it is bounded by the inverse square law. 240v will give you more distance to react between the tingle radius and the kill radius
lucb1e 2y ago
> Would he still have gone in the water to unplug the piano if he was in Europe? Given that they did feel tingling, honestly I am not convinced one should follow that example anywhere on earth. The post also describes that the breaker thing trips when the electricity takes an "some other route than expected" (their words), which I'd say tingling is indicative of: some electricity was being conducted away via the water and, at some point, their foot. Yet the breaker no trip, so either it wasn't a protected circuit or they drew another wrong conclusion based on that aquarium observation which they expected to go differently based on a previously wrong conclusion. If you can assume the water has a similar conductivity as the tap water in the aquarium (not sure that's a safe assumption after it flooded a room with all sorts of dust and objects in it), and you can assume that your body can handle more electricity than the breaker needs to trip, then a fairly short distance ought to indeed insulate you well enough, but the objective was to get close and turn it off. The post sounded like they based this "I'll do it" opinion basically on the hairdryer-in-aquarium thing which we already know didn't go as expected. To me, the situations "hairdryer runs by itself in water" and "I, standing on a ground, stick my hand near the device's off switch in the water" are two very different things. There could easily have been further unknowns -- and apparently there were since the breaker didn't function in the way that this very post describes it should. Since moving to Germany I've often noticed wariness around "Halbwissen" (loaning the word since it carries extra connotation), meaning half-knowledge but not in the sense of "you know something about it!"; rather, you kinda know but you don't know the details and that causes overconfidence. That works out until it doesn't I don't honestly subscribe to that a whole lot: you can't know everything about everything and we use partial knowledge all day long for nearly every topic. Also electricity, I've noticed before a lot of mysticism and fear goes around unnecessarily. So I like the part where experimenting, when done carefully (letting it dry, using a protected circuit, being aware that it might fail and you should observe it first), is encouraged. However, this particular bit about going into the water and "I felt the electricity but everyone cheered me on!" is not what and how you're supposed to do these experiments
morsch 2y ago
I was immediately reminded of the stern warnings to keep out of flooded basements until you've made sure the electricity to the house is cut off. I found[1] at least one person who died this year because of this lesser-known risk of flash-flooding (the more intuitive concern is drowning because you can't open the door due to water pressure). It's possible that it was more voltage at play, though, there are 400V lines in most German homes (electrical heating and stoves, mostly). [1] https://www.rnd.de/panorama/67-jaehriger-will-keller-leer-pumpen-und-stirbt-durch-stromschlag-G3IG6K5BVEWEKH7YZQ5IG6Z3UU.html https://www.rnd.de/panorama/67-jaehriger-will-keller-leer-pu...

Spellman 2y ago

Luckily we have equations for this! Assume that the water has a fixed resistance of R. You have increased the Voltage V about double. As a result of V=IR, the I, or current flow, will be doubled. Which in this case is probably a moderate tingle since R is so high. For reference, the heart muscles start getting involuntary twitches around 100mA, and at 200mA causes cardiac arrest. And the standard units of Voltage, Amp, and Ohm will serve you well here for any conversions.

pvillano 2y ago
You'll get the same tingle at a greater distance. In fact, if the current is finite and current density decreases with distance, it is bounded by the inverse square law. 240v will give you more distance to react between the tingle radius and the kill radius

lucb1e 2y ago

> Would he still have gone in the water to unplug the piano if he was in Europe? Given that they did feel tingling, honestly I am not convinced one should follow that example anywhere on earth. The post also describes that the breaker thing trips when the electricity takes an "some other route than expected" (their words), which I'd say tingling is indicative of: some electricity was being conducted away via the water and, at some point, their foot. Yet the breaker no trip, so either it wasn't a protected circuit or they drew another wrong conclusion based on that aquarium observation which they expected to go differently based on a previously wrong conclusion. If you can assume the water has a similar conductivity as the tap water in the aquarium (not sure that's a safe assumption after it flooded a room with all sorts of dust and objects in it), and you can assume that your body can handle more electricity than the breaker needs to trip, then a fairly short distance ought to indeed insulate you well enough, but the objective was to get close and turn it off. The post sounded like they based this "I'll do it" opinion basically on the hairdryer-in-aquarium thing which we already know didn't go as expected. To me, the situations "hairdryer runs by itself in water" and "I, standing on a ground, stick my hand near the device's off switch in the water" are two very different things. There could easily have been further unknowns -- and apparently there were since the breaker didn't function in the way that this very post describes it should. Since moving to Germany I've often noticed wariness around "Halbwissen" (loaning the word since it carries extra connotation), meaning half-knowledge but not in the sense of "you know something about it!"; rather, you kinda know but you don't know the details and that causes overconfidence. That works out until it doesn't I don't honestly subscribe to that a whole lot: you can't know everything about everything and we use partial knowledge all day long for nearly every topic. Also electricity, I've noticed before a lot of mysticism and fear goes around unnecessarily. So I like the part where experimenting, when done carefully (letting it dry, using a protected circuit, being aware that it might fail and you should observe it first), is encouraged. However, this particular bit about going into the water and "I felt the electricity but everyone cheered me on!" is not what and how you're supposed to do these experiments

morsch 2y ago

I was immediately reminded of the stern warnings to keep out of flooded basements until you've made sure the electricity to the house is cut off. I found[1] at least one person who died this year because of this lesser-known risk of flash-flooding (the more intuitive concern is drowning because you can't open the door due to water pressure). It's possible that it was more voltage at play, though, there are 400V lines in most German homes (electrical heating and stoves, mostly). [1] https://www.rnd.de/panorama/67-jaehriger-will-keller-leer-pumpen-und-stirbt-durch-stromschlag-G3IG6K5BVEWEKH7YZQ5IG6Z3UU.html https://www.rnd.de/panorama/67-jaehriger-will-keller-leer-pu...