It is supposed to disconnect the power in case of a surge from water... It's a safety mechanism designed to keep someone from electrocuting themselves by dropping a curling iron, toaster, radio, etc. in water. GFIC I believe. The button can be pushed to test it, if it will not give power when the button is "popped" it works correctly. edit: link to info ---> http://saltaquarium.about.com/library/blank/bl_GFCI.htm
Well I'll be garsh darnnit! I learned something today. When I went to take a pee the light was on and the button was out, so I pushed it in, hee hee, and thought about what the hell is it for anyway?
Just an FYI, sometimes other power outlets are run off of them, so if you have a non-functional outlet in your bathroom, make sure none of your GFI circuits have been tripped.
This is worth noting twice! My 7 year old tripped the circuit in his bathroom and it shut power off in mine. It left me scratching my head trying to figure out why I had no power, till I checked his bathroom and saw the button popped out.
Hey, all the credit goes to MadMax for the setup. He is the king of Mr. Mom quotes. Irv!! Cleanup on isle 4!!!!!!