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Hasn't this "lower DC voltage is safe" nonsense from the Edison days been thoroughly debunked yet? The safety differences between 12V and 24V are largely trivi

Hasn't this "lower DC voltage is safe" nonsense from the Edison days been thoroughly debunked yet? The safety differences between 12V and 24V are largely trivial. Mostly comes down to wire sizing as 24V can use smaller wires to carry the same power, which some may argue is safer than 12V as the current is halved (but I wouldn't) Modern chemistry batteries are VERY good at providing their stored charge instantaneously across their terminals. Lookup videos of someone dropping a wrench on a car battery for a real life example (spoilers: the wrench welds itself to the terminals immediately and spectacularly.) Humans, as big bags of ferrous liquids, literally have only our skins to help increase our impedance against electrocution when touching ANY metal in series with a battery short. A measley 100 _milli_ amps is enough to stop our hearts. Let's not pretend DC batteries are safe and treat 12V and 24V batteries with the same caution they deserve. I would hope emergency responders are trained against electrocution risks regardless, as fuses can be bypassed when crushed metal is involved near battery compartments in any crash. As for fire concerns it's more about battery chemistry than voltage. Lithium ion being more combustible than lead acid, nickel cadmium.

sandworm101 3y ago
24v is only a little more dangerous than 12v, but so is 48v only a little more than 24v, and 110v only slightly more than 48v. One has to draw a line somewhere. 12v barely penetrates dry skin, and won't do anything across even a cotton shirt. If that is enough for powered windows, why change what isn't broken. As for first responder training, assume they have none. The first person at a scene will be some rando person reaching in to pull a kid out of a burning car, or it is that kid themselves climbing out of the wreckage.
- drzaiusx11 3y ago
  Since the resistance of human skin is fairly constant (1k-10k ohm without open wounds, limited persperation), increasing voltage increases power absorbed across your body and thus the danger exponentially by a factor of 2: P=V^2/R
Grazester 3y ago
The whole wrench thing has happened to me. It was on the bigger 12 volts marine/industrial batteries connected in parallel series for 24 volts to start a Detroit Diesel 71 series engine. There was a nice arce and the end of the wrench melted.

sandworm101 3y ago

24v is only a little more dangerous than 12v, but so is 48v only a little more than 24v, and 110v only slightly more than 48v. One has to draw a line somewhere. 12v barely penetrates dry skin, and won't do anything across even a cotton shirt. If that is enough for powered windows, why change what isn't broken. As for first responder training, assume they have none. The first person at a scene will be some rando person reaching in to pull a kid out of a burning car, or it is that kid themselves climbing out of the wreckage.

drzaiusx11 3y ago
Since the resistance of human skin is fairly constant (1k-10k ohm without open wounds, limited persperation), increasing voltage increases power absorbed across your body and thus the danger exponentially by a factor of 2: P=V^2/R

Grazester 3y ago

The whole wrench thing has happened to me. It was on the bigger 12 volts marine/industrial batteries connected in parallel series for 24 volts to start a Detroit Diesel 71 series engine. There was a nice arce and the end of the wrench melted.