It's easy to learn how to install a garbage disposal. You don't need advanced skills in plumbing, since disposals attach to the sink drain, which is dry unless you're running water. Electrical service can be challenge, however, if your home isn't set up for garbage disposal installation.
A disposal requires a dedicated outlet under the sink. The outlet must be on a 12-volt, 20-amp circuit breaker. The outlet should be a standard outlet. You'll also need an electrical switch mounted near the sink. If you don't have the required electrical hookup, hire a professional electrician to set this up.
Tools Needed
Steps to Install a Garbage Disposal
Prep the area under the sink by removing everything from the cabinet. Then remove the existing sink strainer. This is done by removing the "J" trap first.
Put a bucket under the "J" trap. Using a wrench, loosen the nuts on the "J" trap and remove it. Dump any water in the "J" trap into the bucket. After the "J" trap is out of the way, find the large nut that holds the strainer in place and remove it.
With the nut removed, you should be able to take the old strainer out of the sink. If the strainer is stuck, you can use the putty knife to pry it free.
Using plumbers' putty, form a ring around the bottom of the sink drain. Press the sink flange on the disposal firmly into the putty.
Under the sink, slide the gasket and mounting ring up the flange. Connect the snap ring to keep the gasket and ring secure.
Tighten the three mounting bolts evenly. While you are tightening the bolts, some plumbers' putty will ooze out from under the flange. Simply wipe away the excess.
Next, you will wire the disposal. Look for the cover plate for the electrical connections on the side of the unit. Take off the cover plate to expose three wires: one black, one white and one green. These may be bare copper in some disposals. Check the installation manual for the correct wiring sequence. If the wires aren't pre-stripped, use the wire strippers to remove about 3/4" of insulation.
On the side of the disposal, you will find a hole leading to a Romex connector. Slide the cord through the hole so that the black cord sheath is under the connector's metal. Tighten down the bolts on the Romex connector to hold the wire in place.
Make the necessary wire connections (black-to-black, etc.) using wire nuts. Place all the wires into the chamber and replace the cover.
If you have an under-counter dishwasher, you need to clear the inlet line on the garbage disposal. A closed end tube is located on the side of the disposer near the top. This is the dishwasher inlet line. Take a screwdriver and hammer and knock out the plug.
The disposal is ready to be mounted. You simply line the three nubs on the disposal up with the mounting assembly. After placing, the nubs into the assembly, turn the disposal to lock it into place.
It is time to connect the plumbing. If you have a dishwasher, connect its drain line to the inlet port on the disposal. Reconnect the "J" trap as well. If the "J" trap doesn't line up, you can use some PVC plumbing pipe to get everything to fit. After connecting all the plumbing, you should double check that all the lock nuts and lines are tight. Near the mounting assembly is a rotating cam collar. With a screwdriver or wrench for leverage, tighten the collar down. This will lock the disposer into place and solidify the installation.
Turn on the faucets to check for leaks. Tighten any loose connections. You are ready to restore the power for the outlet. Plug in the disposal test it out.
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