How to kill power to dishwasher (hard wired)

I would like to be able to kill power to my dishwasher if my main water valve closes due to a detected water leak somewhere in the house.

My dishwasher is hard wired and I’m little gun shy/confused about what I should get. I have a Shelly1 lying around but that only has inputs/outputs for L and N. But I need ground as well. Or do I? Could I just cut the current power wire going to the diswasher in half. Re-connect the ground wires, then connect the L and N wires on either side of the cord to my shelly1?

As long as you keep the ground to your dishwaser you are good. Consider this, you replace the hardwired with a box and a duplex outlet and power cord to dishwasher. Then the dishwasher is nothing but a plug in appliance. Still UL listed with shelly in the box. Many dishwashers are set up with an outlet below the sink. Hope this clarifies.

EDIT: You do need to be concerned with the amperage draw of your dishwasher. If I remember correctly shelly 1 is rated for 15 amps. Normal dishwasher will have 20 amp circuit with 12 gauge wire.

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Thanks. I’ll check my breaker. I was just thinking about this from work and a google search said most dishwashers dont draw more than 10 amps.

You actually only need to interrupt the live wire. I suspect the two neutral connectors are internally linked. This is just how a fuse works if you have fused plugs. Always leave the earth wire connected.

Shelly 1 needs a neutral wire and two live wires and a load wire. Here is the wiring diagram

So the black (load) from the DW will be connected to ‘O’. Black from the breaker will be pig-tailed twice and go to ‘L’ and ‘I’. Neutral (white) from line and load will be pig tailed to ‘N’.

If there is just one wire it will need to be cut at the box leaving at least 6" and a new load wire run. If there is no box you need to install one. Use an old work box. The ground wires need to be crimped together. Don’t forget to twist all connections then wirenut or you can use the push-in connectors.

So the breaker is a 20amp, listed next to it is “Dishwasher, disposal”

The tag on the dishwasher says max 8.1 amps.

Am I ok with 16amp Shelly1 going to the dishwasher? I should I get something thats 20+?

Also, what the the heck? They must have like ran the power cord under the floor right behind the dishwasher because I checked under the sink and theres no cord in there coming from diswasher! So now I gotta pull it out.

You have a good safety factor. You are fine to run 15 amp shelly servicing a 8.1 amp device. You will pull ~1000w and shelly 1 rated to 3500W I am guessing that they ran romex straight to the dishwasher. It meets code and is fine. It should be out of a single gang box. you will have to cut make all connections and stuff everything back into the box.

Hold on!
Its not the as much the power drawn when its operating normally that you have to be concerned with.
Its the power drawn when its out of bound, like malfunctioning.
When its malfunctioning, then something might get shorted and the draw might exceed the limit of the Shelly, but not the limit of the fuse and this is where the dangerous situation occur.
You should look into a implementing a fuse lower than the limit of the Shelly between the Shelly and the dish washer.
Then the fuse will burn out before any harm can occur.

If this worries you run a Shelly 1 PM UL with over power and temperature protection. And just for clarity probably not a fuse but a breaker.