I'm adding a new dishwasher to an older home. Due to space constraints, it will be a small 18 inch unit (rather than a standard size 24 inch) unit. The power requirements call for "120V 60Hz 9.0A". There is currently no power outlet or wiring under the sink / cabinet area where the DW will be installed, but I could easily run a wire. My question is this; based on this level of power requirement can I power the DW by just extending off an existing line that has an outlet or two on it, or do I have to run a completely new line from the breaker box to the DW with nothing but the DW on that line?

I would run a new line for this but you don't necessarily have to. Most circuits are 15 or 20 amp max but you don't want to exceed 80% of that consistently. So if the circuit you tie into already has a few things on it this would be out of the question.

Keep in mind this will draw 9 Amps; say you have 15 amp circuit so you really want it to only power 12 amp (15*80%). That would leave only 3 amps left on the circuit which would not been enough to power much of anything.

Do not ties this into the 20 Amp circuits that go to your Kitchen counter (I am making an assumption here that is your setup). This is because kitchen appliances can draw quite a big load and 9 amps on top of that would not be good.

I would run a new 15 or 20 amp line for this.


***I am not an electrician just know what I have read and learned here***
This is just friendly advice

The 80% rule, applies only to continuous loads. Those loads that are on for more than 3 hrs at a time and some others. Electric heating, for instance, is considered a continuous load.
A oven in a residential setting is not considered continuous, but in a commercial setting, it is.

Rounding up, to the next available breaker is generally OK, so a 9A dishwasher on a 15A circuit is OK.

It would be wise to put it on its own breaker.

I agree with comment # 2 form uber member. I am not an electrician, but a general contractor doing mostly remodels. I'm not sure if it is still code, but the dishwasher could not be hard wired direct from either the panel or from the last outlet from a separate circuit. If hardwired it needed to be fed from an exposed switch. Or wired with an extension cord type #14 wire with a plug, We would install an outlet under the sink in which to plug in. The reasoning for this is if the unit itself caught fire, you could stop the flow of electricity to appliance.. Not sure if this code remains. I still wire this way, it just seems like good common sense. If you smell smoke, you can either switch or unplug the unit.

You can hard wire the unit if you provide a breaker lock. It has nothing to do with the unit catching on fire. It has to do with servicing the unit.

This thread is over three years old also.