I build in some kind of method to pulse all my transformers with redstone, which miraculously un-sticks them when this inexplicably happens.
"Drat, blew a fuse again, better head to the basement and hit the big reset-everything button."
Note that some delicate or careless designs will not tolerate a temporary transformer polarity reversal, but so far there's only been one serious explosion.
The above happens if you spray construction foam on wire (tested tin and glass fibre) with current flowing through it, quit, and then reload. It hangs on the "saving chunks" screen. Re-reloading the world after the crash will allow Minecraft to recover, but the entire chunk that contained the CF-coated wire will be reset to a natural state (as it was before you started building) with devastating consequences.
