I searched this topic but only found a post specifically about power strips in a few inches of water not shorting out and this is different: My basement was flooded (murky brown water, not salt water) full to the ceiling, with the entire electrical system underwater: the main service line, 2 breaker panels, several outlets, light sockets, and all utilities under water. The power in the neighborhood went out (hurricane) during this flood. A day or so later it came back on and all the electricity started working again, including the sump pump kicking on and ejecting the entire basement of water, like the amount of a pool. A light bulb was even filled with water and still worked (not incandescent; maybe LED?). Not one breaker blew; the whole house worked fine. (everything underwater was replaced regardless)
I’m baffled. Shouldn’t breakers have flipped or shorts happened?
If anyone mentions grounding, I don’t really even grasp that, so please really ELi5, thanks.
In: Physics
I was kinda curious so I took a cup of tap water and threw in my multimeter in there, total resistance is about 2.5 million ohms, which is a lot.
Water alone is not really a good conductor of electricity, salt water is much much much better. Your murky water was probably better than my tap water still not enough to trip your breakers, which are 20 amps. Which is a lot. You’d need to bring that resistance down to 6 ohms. Your water isn’t anywhere close here.
Your circuit breakers in your house aren’t designed to prevent you from dying of electric shocks or to break when water gets in, they are designed to prevent your house from burning down from overloaded wires overheating. And it actually takes a lot of current for that to happen, once again 20 amps is no joke.
What will trigger is what’s called Ground Fault Circuit Interruptors (GFCI), these are the outlets required in your bathroom with those test and reset buttons. These use some clever engineering to make sure the current into the outlet is the same going out, and if not it trips, this usually happens if you touch some metal that is somehow connected to this outlet and the current goes through you to ground instead (and by ground we mean anywhere else beside the other outlet pin, which usually makes its way to the literal ground), hence the name. These outlets are actually what are designed to save your life, and you should be testing them periodically with those buttons. You might think those buttons are an on off switch, but that test button actually pushes a metal tab to short the outlet to ground to test the mechanism.
So if water is so resistive, why is it so dangerous?
It’s because it doesn’t take a lot of current to kill you. Your heart uses a tiny amount of electric current to control its beating, if an external shock messes this up, this may cause your heart to go out of sync or stop entirely. Water, while not a good conductor, is still a lot better than many things, especially dry skin, and can deliver enough electricity to kill your heartbeat.
If I remember secondary school chemistry, itll be something to do with electrolytes (aka Salt) content of the water and distance between the 2 electical things sticking in the water.
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