While playing I used the Power Shutoff to make a machine that would allow power to go to a smart battery while shutting down the output. (Basically a makeshift power transformer.) I did this because even when the two sets of circuits are separated using the power transformer, the game believes that they are connected. So two lines that wouldn't overload a conductive wire now combine for some reason and do overload the wire. I don't know if this is intentional or not I just wanted to put it out there. Sorry if this is an game mechanic!
Have two different power grids
Send one grids energy through a power transformer into a smart battery
Set the smart battery so that when it reaches full it shuts off the first grids transformers (Via their automation or a power shutoff)
While shutting down those transformers, activate other transformers connected to the other grid