A garbage disposal doesn’t necessarily need its own dedicated circuit but the circuit must be able to handle its operating current (and the current of any other appliances on the same circuit).
This post will go into 4 considerations you need to make when wiring for your garbage disposal unit.
Garbage Disposal Wiring Overview
A garbage disposal is typically plugged into a power outlet to operate.
Power outlets will be wired with a cable that leads back to the switchboard. In the switchboard, this cable will terminate into a fuse or circuit breaker. The goal of this circuit breaker is to protect the property in case a short circuit or overload occurs.
An overload is a type of fault that occurs when too much current is being drawn through a cable. When this happens, a cable will heat up to dangerous levels before eventually catching on fire. A circuit breaker exists to shut off power in case this happens.
An overload can be caused by a single appliance drawing a big load, such as an electric heater.
It can also be caused by many appliances collectively drawing a large load.
As we would rather not overload the circuit, it is important to ensure that the right sized cable is used depending on the load of the appliance or appliances.
A larger cable is able to handle more current without heating up. As a result, larger cables are used for larger load requirements.
Let’s look into four considerations you should consider when wiring for a garbage disposal.
1. Check The Electrical Specifications For The Garbage Disposal
The installation manual for the garbage disposal should have its electrical specifications.
The manual may also be available online on the manufacturer or retailers website. The electrical specifications will have key information such as:
- Power rating in watts.
- Operating voltage (This is needed for the garbage disposal to run. When the voltage deviates it can cause problems for appliances.)
- Frequency.
- Operating current.
- Fuse rating.
The operating current tells us how much current the garbage disposal will consume during operation. This is important when deciding the appropriate cable size for the circuit.
For example, if the garbage disposal is rated at 1000 watts (4.34 amps at 230v), then the cable must be able to handle this 4.34 amps plus the current of any other appliances using the circuit.
2. Check Operating Current Of Other Appliances On Same Circuit
In addition to the above, we also need the operating currents for other appliances that will be using the same circuit. As a garbage disposal is located in the kitchen some examples of appliances include microwaves, refrigerators and dishwashers.
The amount of time that an appliance is operating also needs to be taken into account. A fridge will be on 24/7, but a garbage disposal will only be used for short periods of time.
3. Determine Cable Size Required
A garbage disposal is typically plugged into a power socket but it could also be hardwired.
A power socket is typically wired with 1.5mm2 or 2.5mm2 cable.
These cables are protected by 16A and 20A circuit breakers respectively. If exceeded the breaker will trip.
As we now know the operating currents of the garbage disposal and any other appliances on the same circuit we can determine which cable size is appropriate.
For a standard domestic garbage disposal, most cases, a power socket wired with 1.5mm2 or 2.5mm2 cable will be sufficient. The most important thing is to ensure that the cables are appropriately protected as you will see below.
4. Select Correct Fuse Rating
The correct circuit breaker will ensure that the cable is protected from the effects of overload (and short circuit).
As mentioned earlier, current causes the cable to heat up. The larger the cable, the more current it can handle safely. It is therefore important to ensure that the current carrying capacity of the cable is not exceeded and if it is exceeded the breaker trips.
For a 1.5mm2 cable it needs a 16 amp fuse and a 2.5mm2 cable needs a 20 amp fuse. If the 2.5mm2 cable had a 32 amp fuse, it would catch on fire before the breaker trips (in event of overloading the circuit). For this reason correct fusing is very, very important.
Electricians Perspective
Ensuring that the cable is big enough to handle the load of the garbage disposal and any other appliances on the same circuit is step one. Step two is to ensure that the cable is protected with an appropriately sized circuit breaker incase of an overload. This is according to AS/NZS:3000. We Fix Faults is an electrician blog. If you have any questions or information you’d like to share send us a message here.