There are no special reasons why a dishwasher should be on its own circuit.
A dishwasher circuit must be wired with a cable that can handle the dishwasher’s operating current.
There must also be a circuit breaker (MCB) rated at the cable’s current carrying capacity. This ensures that the cable doesn’t heat up and catch fire in the event of an overload.
The main consideration is to check the total current consumed on the circuit doesn’t exceed the current carrying capacity of the cable.
Let’s look at whether or not your dishwasher needs to be on its own circuit.
Check Dishwasher Specs Online
First find the electrical specifications for your specific model of dishwasher. This can typically be found on the dishwasher retailer or manufacturers website. The specs will contain information about the correct voltage and frequency for the dishwasher (important for correct dishwasher operation as you can see with power surges).
The main information we are looking for is the operating current. It may show on the specs as current range such as 7 – 8 A (amps).
For a dishwasher that uses 7-8 amps, a 1mm2 or larger cable will meet the operating current requirements and a 10A fuse will protect that cable – provided that nothing else is on the same circuit. Normally, you would use a larger cable such as a 2.5mm2.
If other wall outlets are on the same circuit then you will need a larger cable. Normally a dishwasher power outlet is connected to other power outlets. These might power a refrigerator, a microwave, a phone charger.
With this in mind, the cable should actually be larger than 1mm2 (and the fusing should also be larger).
Typically, a kitchen area containing several appliances such as a fridge, microwave, blender, kettle in addition to a dishwasher will be wired with 2.5mm2 cable. This cable will have a circuit breaker rated at 20A. The cable size depends on what else is using current on the circuit.
It is also worth noting that most appliances won’t be running all the time. For example, a dishwasher will run its cycle for a few hours then turn off. It isn’t running 24/7.
The cable is rated for the total current capacity of every appliance running at the exact same time which in reality won’t happen most of the time.
Key Takeaways
From an electrician’s point of view, a dishwasher must be wired with a cable that is larger than the current it consumes (found by checking the dishwasher specifications online). The circuit must also be on a breaker rated to protect the cable from overloading.
This may or may not mean that the dishwasher is on its own circuit.
The dishwasher could be on a circuit containing several other power outlets and appliances. All that matters is the cable rating is known and there is a fuse at that rating.
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