The power switch for the garbage disposal is a common toggle type that looks exactly the same as a light switch, usually mounted on the backsplash, or the wall just above it. Such switches are sold at hardware stores and home improvement centers. The wiring is attached with screw terminals, and the electric configuration is basic. Homeowners who replace their own electric switches save the high cost of hiring an electrician for a service call.
Shut off the breaker switch that controls power to the garbage disposal if it's labeled. Run cold water down the drain with the disposal, turn the disposal on and ask a helper to flip breaker switches until the unit goes off if that breaker is not labeled. Shut off the main power breaker and perform the switch replacement during daylight hours if the correct breaker cannot be identified due to a lack of power to the disposal. Leave a note or a lock on the breaker box to prevent anyone from restoring the power while you work.
Use a slotted screwdriver to remove the two screws holding the cover plate. Use a Phillips screwdriver to remove the two mounting screws that hold the switch to the wall box. Gently pull the switch out from the wall to expose the terminals and attached electric wires.
Check the terminals with a voltage tester to be certain the power is off. Take note of the wire colors secured to each terminal. The typical arrangement includes two wires connected to top and bottom terminals on one side that complete or break the electric connection, and a ground wire on the lower ground terminal. Use masking tape to label each wire if needed to remember which color goes to which terminal.
Remove the wires by loosening them from each terminal with a slotted screwdriver. Purchase a replacement switch that matches the old one exactly. All switches are not the same. In all likelihood the garbage disposal is controlled by a single pole, single throw component. Disposal switches require the off position to be marked. Bring the old switch to the hardware store for reference if you have any questions about its type.
Cut off the bare wire ends and strip off 1/4 to 3/8 inch of insulation with wire cutters to expose new wire ends for connection to the new switch. Place the wires on the terminals in the exact order they held on the old switch. Wrap bare wire around the terminals in clockwise rotation and tighten the screws so the heads cover all wire threads.
Press the wires gently into the wall box and secure the new switch by replacing the mounting screws. Put the cover plate over the toggle and secure its holding screws. Turn the power back on at the breaker box and test the switch by running cold water into the sink that holds the garbage disposal and flipping the new switch to the on position.