There are garbage disposals that come with a pre-installed power cord, and there are those which do not. It is easy to wire a garbage disposal with a pre-installed power cord; all you have to do is plug it into a socket.
Those garbage disposal models do not come with a pre-installed power cord makes the installation difficult for new DIYers. In such cases, you will have to purchase a power cord separately and wire it to the garbage disposal. Sometimes, you will have to hardwire the disposal directly to the circuit.
How to wire a garbage disposal
Time needed: 20 minutes.
Wiring a garbage disposal may sound scary to many, but the process is straightforward. Follow the below steps to wire your garbage disposal to a power cord or hard wire it to the mains.
PS: Wiring should be done before hooking up the garbage disposal to the sink.
Locate the wiring compartment and remove its cover
If your garbage disposal didn’t come with a pre-installed power cord, look on its bottom side to locate the wiring compartment. This compartment will be kept closed with a metallic cover using a screw. Unscrew and open this compartment.
Pull out the black and white wires in the wiring compartment
Inside the wiring compartment are two wires; one colored white and the other black. Pull these wires out. The ends of these wires are usually stripped. If not, strip them with a wire stripper.
Tighten the Romex connector onto the garbage disposal
If your garbage disposal is InSinkErator, its power cord comes with a Romex connector. Romex connector is basically the hole through which you insert the power cord’s end to connect it with the garbage disposal. The Romex connector holds the power cord firmly in position. This prevents the electrical connections from separating due to vibrations.
Insert all the wires of the power cord through the Romex connector into the wiring compartment
Loosen the two screws on the Romex connector and insert all three wires, including the ground, into the Romex connector and take them out through the wiring compartment’s opening. Tighten the two screws of the Romex connector and make sure that the wiring is secure.
Connect the wires
If you look closely at the two black wires of the power cord, you can see that one of them is ribbed. Connect that ribbed wire to the white wire from the garbage disposal. Also, connect the other black wire to the black and yellow wire from the garbage disposal. You can see a green screw in the wiring compartment; connect the ground wire to this screw. Secure the connections using the two-wire nuts provided. Make sure you do not overtighten the wire-nuts. Then wrap the wires with electrical insulation tape.
Reattach the wiring compartment cover
Carefully push the wires into the wiring compartment of the garbage disposal. Then re-attach its cover using a screwdriver. Now you have the garbage disposal wired and ready.
Here is a detailed video showing this step by step installation;
PS: The credit to the image on Step 2 goes for this video.
These steps are detailed in an instruction manual that comes with your garbage disposal. If you don’t have this manual, here is it.
Garbage disposal wiring diagram
It is pretty confusing for many people when it comes to hardwiring a garbage disposal. In this case, the wires from the wall switch installed above the countertop are connected directly to the garbage disposal. Here’s a simple wiring diagram for that;
Here’s a good and short video I found on Youtube detailing the wiring diagram for a garbage disposal. You can’t go wrong with your wiring once you watch this;
What if I don’t have a power outlet under the sink
It is easy to wire a garbage disposal, and I always recommend DIYing it. However, installing a power socket under the kitchen sink is entirely a different matter. If you don’t have a power outlet under the sink, I recommend hiring a licensed electrician. Trying to do this installation yourself can lead to more problems.
Does a garbage disposal need a dedicated circuit?
Even though the power outlet of a garbage disposal is installed close to the water, it is not required to have GFCI protection. A dedicated circuit is recommended, but it is not mandatory (source).
This means you can connect the garbage disposal to the same power outlet you use for a dishwasher. If your disposal needs a dedicated circuit, it will be written so in its instruction manual.