Wiring a dishwasher is not an easy task if you have never wired an appliance before. Strong attention to detail is required for your safety when wiring a dishwasher or any other task that involves dealing with electricity. Not following instructions when dealing with wiring an appliance also may cause irreparable damage to part or all of the appliance you are connecting. Because of the power consumed by a dishwasher, ensure that it can be installed on an unshared circuit breaker. With the right tools, equipment, and safety in mind, you can have your dishwasher wired in less than an hour.
Step 1 - Install 20 Amp Breaker
Your new dishwasher needs its own power supply. Install a 20-amp breaker in your breaker box. Open the panel of your breaker box and select the position you will install the breaker in. Secure the breaker and label it appropriately on your electrical panel schedule. Leave the breaker off until you have finished the wiring process.
Step 2 - Run Cable
Run the 12/2 NM cable from the breaker box to where you will install your dishwasher. You should plan to have an excess cable of approximately 2 to 3 feet should you have to move the unit to perform maintenance on it in the future.
Step 3 - Locate Junction Box
You will find the junction box at the lower rear of the dishwasher. Remove screws holding the cover in place and you will see three wires, one black, one white, and one green. Depending upon the make and model of your dishwasher, you may see a green ground screw instead of a green ground wire.
Step 4 - Remove Knockout
On the side of the junction box, you should see the knockout. Use your needle nose pliers to remove the knockout. The knockout may sit firmly in place so a steady force may be necessary.
Step 5 - Insert Wire Connector
Once the knockout is removed, place the electrical wire connector through the hole and use the nut to secure the wire in place.
Step 6 - Prepare NM Cable
You can attach your NM cable once you prepare the wires inside. Remove the jacket from the NM cable with your wire stripper to expose the black, white, and green wires inside. Once these wires are exposed, use your wire stripper again to remove approximately an inch of the insulation from each wire.
Step 7 - Place NM Cable
Once the wires are prepared, place the wires through the wire connector until some of the jacket shows inside passed the connector. There is a clamp outside the connector that you will need to tighten with your screwdriver once the wires are through the connector. After they are tightened, the cable should be secure in place.
Step 8 - Connect Wires
Now you can begin matching the colors of the wires together. Twist together the ground wire first. After each set of wires is twisted together, be sure to use wire connectors to keep them together.
Step 9 - Prepare to Test
When all wires are secure, replace the junction box cover to protect the wires. All that is left to do is connect your hoses to the dishwasher properly and turn on your breaker once you are done to test the connection.