It's a simple case of physics, right?

So let me get this straight. No electricity needed to be turned off except for the circuit that went to the old electric water heater when it was removed, but now that a new one is being installed, ALL ELECTRICITY to the place has to be turned off?

Big sis came over to begin a look at things and warns me that she "might" have to turn the electric off, meaning ALL electric, just to install something that already has the electric to it turned off. I warn her that if she turns off ALL electric, the TV which I've been having problems with might not turn back on. I see absolutely no need to turn all the electric off for a circuit that's already off and was off when the old wires were being disconnected from the old heater. By that logic, shouldn't have all electric been shut off THEN?

I don't know if she got irked at me telling her that she shouldn't need to turn all electric off, because she comes back with that I don't know what she'll need to do to hook up the new heater, among other things, took a look at something, then left.

If I can replace electrical sockets without turning off a breaker, she should be able to hook up electric service to a water heater on a circuit that's already off without depriving the rest of the place of electric. It's simple physics. Don't Cross The Streams.