Garbage disposals are typically installed by licensed plumbers or professional handyman services. Some appliance stores or manufacturers may also offer installation services.
Electricians do not install garbage disposals. However, an electrician is needed if there is no power outlet under the kitchen sink to connect the garbage disposal.

A plumber installing a garbage disposal
Even though this is generally the case, many scenarios can be confusing. Officially the plumbing part should be done by the plumber, and the electrician should do the electrical part. But if there is already an electrical outlet under the sink, it is unthinkable to hire an electrician just to plug in the garbage disposal.
What if the garbage disposal doesn’t have a pre-installed power cord?
In most cases, plumbers will ask if there is an outlet under the sink. Also, many garbage disposals come with a pre-installed power cord so all there is left for the plumber is to plug it into the power socket. But what if the garbage disposal doesn’t have a pre-installed power cord?
If the garbage disposal doesn’t come with a pre-installed power cord, you will have to hire an electrician to do the electrical part of the installation. The electrician will open a terminal plate on the underside of the garbage disposal and wire the power cord (new or existing) into it.

But this part of the installation is something you can do by ourself, and it is usually detailed in the garbage disposal installation manual. It is pretty basic, and anyone can do it (even though your plumber may refuse to do it officially)
How to wire a garbage disposal DIY?
Wiring a garbage disposal is pretty easy. Here is a video detailing its step-by-step installation;
While many garbage disposals come with preinstalled power cords, many models by InSinkErator do not have them. But you can opt to buy one of them with a pre-installed power cord. InSinkErator does this to reduce the disposal’s overall cost, so the customer isn’t forced to buy a power cord if he or she has one already.
Here is a detailed guide on wiring your garbage disposal DIY: How to wire a garbage disposal
What if I don’t have a power outlet under the sink?
If you don’t have a power outlet under the sink, then you need to get one installed before installing the garbage disposal. For this, I recommend hiring an electrician, partially because I myself am not good at it. Also, it will require some level of electrical expertise to install a new outlet under the sink in compliance with the electrical code of your state. Failing to do this correctly can also void the warranty of your appliance.
Depending on the type and power rating of the garbage disposal, you may need to install a dedicated electrical circuit for it. You can use the dishwasher outlet for the low-powered and inexpensive 1/3 HP garbage disposals, but as the power rating increases, it is recommended to use a GFCI outlet. While it is not mandatory to use a GFCI outlet according to code, it will help your appliances and family from electrical fires.
Do I require a plumber to install a garbage disposal?
You do not require a plumber to install a garbage disposal. Installing a garbage disposal is a pretty easy task, and I always recommend people do it themselves. There are lots of youtube videos available which explain the installation process in detail, and you can find the same for any garbage disposal models. Also, the installation of all garbage disposals is the same except for a few differences due to the type of sink mount they use. Garbage disposals by Waste King use an EZ sink mount, while those by InSinkErator use 3-bolt mounts. Other than this, the installation process is exactly the same, and anyone can do it themselves.
However, if you are too worried about DIYing the installation, I recommend hiring a plumber to do it. This is a costly affair; however, mistakes during installation can void the warranty of the disposal as well as cause other damages.
Who installs the air switch for a garbage disposal?
I always recommend using an air switch to operate a garbage disposal. Air switches are safer because it doesn’t have any direct electrical connections so the chances of electrocution are zero.
A garbage disposal air switch is installed by a plumber, not an electrician. You can also do the installation yourself if you feel confident enough.
Here is a quick video detailing the installation process of a garbage disposal air switch;
Whom to call when a garbage disposal has electrical problems
It is recommended to call a plumber if your garbage disposal has electrical problems. This is because plumbers are more familiar with garbage disposals than electricians, so they will be able to diagnose the problem quickly.
Eventually, you will need an electrician’s help to rectify the problem, but it is the plumber I will call first. But in most cases, electrical problems like a burned motor or a constantly tripping reset button are hard to fix, and the solution is usually replacing the garbage disposal. So plumbers are the ones to call if your disposal runs into trouble.