A dishwasher should have its own circuit. Have an electrician install the circuit and fish the cable to the area where you will install the dishwasher. Then follow the installation instructions of the dishwasher's manufacturer. Below are guidelines on how to make the wiring connections.
The internal wiring of a dishwasher terminates in the power junction box, just behind the dishwasher's kick panel. The connecting wires are black, white, and green. A green grounding screw is sometimes substituted for the green wire.
1.
Remove a Knockout
Make sure power to the circuit is turned off at the main panel. Then, using a knockout punch, remove a knockout on the dishwasher's junction box.
2.
Secure the Cable
Pull the 12/2G NM branch-circuit cable into the box. Be sure to leave extra wire (3 to 4 feet) looped behind the dishwasher so that the appliance can be pulled away from the wall for later servicing (Fig. 1). Rip back the cable sheathing, cut away the excess, and secure the cable in the box using a cable clamp.
3.
Strip the Wires
After exposing the insulated wires, use a multipurpose tool to strip them from the branch-circuit cable.
4.
Make the Connections
Splice the black hot wire from the branch-circuit cable to the black hot wire from the dishwasher; cap with a wire connector. Then do the same with the white neutral wires. Lastly, splice the bare copper grounding wire to the green appliance wire (if present), or connect it to the green grounding screw in the dishwasher's junction box to complete the appliance wiring. (Fig. 2)
