How far would electricity carry in the sea?

11 October 2009

Question

How far would electricity carry in the sea? If a toaster, connected to the mains at 240 volts was accidentally dropped into the ocean, let’s say the North Atlantic, would the sea life be electrocuted? And if so, how far and how deep from the toaster would these electrical shockwaves travel?

Answer

Dave - Seawater conducts electricity reasonably well, but not very well. It's about a 10 millionth as good as copper. So, you will get electricity flowing through it, but it will also depend on where the other cable is because electricity always moves from one place to another place. And if the other connection to the circuit is an awful long way away, then you get very, very small currents and it's not going to do a lot of damage. If you've got two contacts a foot apart and a fish swims between them then it's almost certainly going to get electrocuted. So, I think it depends an awful lot about how you set up this test. Helen - I just like to say, I don't want anyone to go and try this for the sake of the fish and the sake of any divers that might be there. Just in case. Dave - And of course, with a toaster, if it's got a proper three pronged plug, then you got an earth in there as well, so most of the currents can flow within the toaster from the live parts of the toaster to the earth. So, it's probably not... Chris - It probably would just melt the cable, wouldn't it? Dave - It's probably going to draw a very large current and blow the fuse. Chris - I have heard of someone turning a lot of electricity into about a million gallons of very hot water in Australia when a flood happened in Adelaide at a Medical Research Institute and it flooded the basement and flooded the power board, and it didn't trip out for some reason. It just passed a very large current through a large amount of water and made the largest Jacuzzi you've ever seen. So there we are.

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