Designed to perform short bursts of grinding, garbage disposals that won't turn off quickly wear out and malfunction. Despite the simplicity of a garbage disposal's electrical connections, a misplaced power cord often causes the disposal unit to continuously run. Garbage disposals connect to electrical receptacles located inside of the under-sink cabinet. Dual-outlet receptacles often have one switch-controlled outlet and one outlet that's always "on." If your garbage disposal won't turn off when you flip the wall switch, begin your troubleshooting by checking beneath the sink to see if your disposal unit is plugged into the right outlet.
Turn the wall switch that should control the garbage disposal to the off position. Search for this wall switch on the walls surrounding the kitchen sink.
Open the doors to the under-sink cabinet that houses your garbage disposal. Turn on a flashlight. Crouch or sit on the floor to access the interior of the cabinet. Use the flashlight to locate the garbage disposal's power cord. Unplug the garbage disposal's power cord from the electrical receptacle.
Plug the garbage disposal's cord into the under-sink electrical receptacle's other outlet. This outlet is directly above or below the outlet from which you recently unplugged the power cord. If the garbage disposal turns on immediately after you plug it in, then neither of the under-sink receptacle's outlets are controlled by the wall switch and the receptacle must be re-wired. If the disposal does not immediately turn on, return to the sink.
Flip the wall switch that should control the garbage disposal into the on position. If the garbage disposal unit turns on, the cord was plugged into the wrong outlet. Turn the wall switch to the off position.