Both dishwashers and garbage disposals are electrically powered devices. Garbage disposal, situated under the sink, shreds large pieces of food that pass through the drain into smaller pieces to prevent blocking the drain.
On the other hand, a dishwasher, located along with the cabinets, washes dishes systematically.
Can the dishwasher and disposal be on the same circuit?
Dishwashers and disposal units can be used on the same circuit unless the average power consumption of both devices exceeds 80% of the circuitry’s capacity. Most of the time, they work fine but, starting currents of either appliance may cause overloading of the circuit and result in consequences.
Since garbage disposals are mostly repaired, most of them are hardwired. Hardwiring prevents the user from using it on a different circuit. These devices are usually connected to 15A or 20A dedicated circuits due to their high power demands.
Similarly, vintage dishwashers are hardwired to the circuit. However, modern dishwashers come with plugs or hardwiring options, which allows the user to choose from one of the available installation options.
As a result, these dishwashers can be connected to a different circuit that is not already connected to the garbage disposal.
Powering the garbage disposal and dishwasher by the same circuit is not recommended. The reason is that these kitchen appliances require a lot of power to operate, and the starting currents alone can overload the circuit.
If their combined power consumption does not exceed 80% of the circuit’s capacity, they can be used together on the same circuitry.
Do garbage disposals need a dedicated circuit?
A dedicated circuit for garbage disposal is recommended but not necessary. Nowadays, garbage disposals are either hardwired or plugged into a grounded electrical outlet.
Garbage disposals do not have starting currents, and their average power intake remains almost the same throughout the whole operating time. Therefore, they do not necessarily need to be on a dedicated circuit.
However, sometimes garbage disposals consume more power than usual. When such an amount of current is not available, the device may not work and break down. As a result, experts recommend having them on a dedicated circuit of their own.
Do dishwashers need a dedicated circuit?
Dishwashers need a dedicated circuit. Unlike garbage disposals, dishwashers need a dedicated circuitry of their own. In most homes, they are connected to the same circuit as the garbage disposals.
A dishwasher circuit should be 120-125V and 15A rated. If the circuit wires have a 15A rating, the dishwasher is connected with a 14/2 NM wire with a ground. But if it is rated at 20A, a 12/2 NM wire with grounding is used instead.
In the case of dishwasher and garbage disposal using the same circuit, the circuit should be 20A rated. 20A rating will prevent overloading the circuit.
5 reasons why dishwasher and disposal can be on same circuit
There are various reasons why a dishwasher and garbage disposal can be on the same circuitry. Below given are some of the reasons:
Not continuous load:
Dishwashers and garbage disposals do not require constant power. While the dishwasher is running, it consumes power for a period.
While the garbage disposal is running, it runs for a shorter period and consumes lesser power than a dishwasher. As a result, having both of these devices on the same circuit is safe as both do not consume power for long.
Not high-power demand:
Dishwashers and garbage disposals do not have identical power requirements.
Since a dishwasher is a large appliance, it requires more power to operate than the garbage disposal. Therefore, even if both the devices run together, there is very little chance of them overloading the circuit and causing electrical fires.
Such a lack of circuits in the kitchen may cause the user to use the hardwiring method for the garbage disposal and the dishwasher, resulting in them being connected to the same circuitry.
Hardwiring:
As mentioned above, hardwiring only gives the user a single choice, that is, to connect the dishwasher and garbage disposal to the same circuit.
As they do not have plugs, they cannot be connected to electric outlets that are connected to dedicated circuitry.
Used one at a time:
It is rare to see the dishwasher and garbage disposal running simultaneously. Since these appliances are used at different times, having them connected to the same circuit is safe.
Connecting them to the same circuitry is safe because when one of the devices are working, it will not overload the circuitry. Also, it will have the additional current capacity to sustain any power surges.
What size breaker for dishwasher and disposal?
Circuit breakers are necessary for the prevention of overloading a circuit. When only a dishwasher is connected to a 15A circuit, a 15A rated circuit breaker will be sufficient to prevent any severe consequences.
However, if the electric circuit supports 20A, a 20A rated circuit breaker will do the job.
If both the dishwasher and the garbage disposal are on the same circuit, and the circuit rating is 15A, install a 15A rated circuit breaker.
A 15A circuit breaker will prevent further overloading the electric circuit if the appliances exceed 80 percent of the circuit’s ratings. In the case of the electric circuitry having a 20A rating, a 20A rated circuit breaker will be helpful.
When both dishwashers and garbage disposal are used on the same circuit, it is recommended by experts and electricians to use a 20A circuit.
This is because, if the electrical circuit is shared between a dishwasher and garbage disposal, it is expected to have a 20A rating.
So, if it is just a dishwasher on its dedicated circuit, the circuit breaker can be either 15A or 20A rated, depending on the ratings of the electrical circuit. And, if the dishwasher and garbage disposal are on the same electrical circuit, then a 20A should be used.
Do all garbage disposals have a dishwasher connection?
Yes, all garbage disposals have a dishwasher connection. But not all dishwashers have a built-in dishwasher or are connected to garbage disposal. But it is not required for a dishwasher to work.
It is rare nowadays to see a dishwasher without garbage disposal. In most modern kitchens, the dishwashers are connected to a garbage disposal system. This connection is to prevent blockage in the dishwasher drain and prevent it from breaking down.
Dishwashers drain the contaminated water and garbage, such as small bits of food, fruits, etc., down the same pipe.
Therefore, the single drainpipe is inserted into the garbage disposal, which shreds the large pieces of food into small enough pieces to prevent any blockage.
A dishwasher alone cannot rid the large food pieces and may break down in case of a pile-up of particles in the drain.
How to connect the dishwasher to disposal?
If your dishwasher is not already connected to the garbage disposal, it is easy to hook it to the garbage disposal. Follow through with the instructions, and you can do it yourself.
First, turn off the garbage disposal. If it is hardwired, turn off the breaker at the breaker panel. Otherwise, if it is plugged in, disconnect the plug from the outlet.
Second, use a screwdriver to loosen the clamp on the drain line connected to the garbage disposal.
Then, insert the new drain line instead of the disconnected pipe and tighten the clamp with a screwdriver. Next, take the drain line and connect it to the dishwasher drain line.
Pushing the dishwasher drain line will secure it enough inside the drain line and connect it to the garbage disposal. If all the procedures are followed successfully, the dishwasher drain will empty into the garbage disposal as intended.
Final Thoughts
A dishwasher and disposal can be on the same circuit as people do not use these devices simultaneously. Check that the total ampere ratings of these devices do not exceed 80% of the circuit’s rating. Using a 20A rated circuit breaker will prevent overloading the shared circuit.