Contemporary 220-volt dryer outlets use a four-prong configuration, with two prongs supplying the voltage, a third connected to the neutral circuit and the fourth to the grounding protection. There are several different prong configurations options for 220 outlets and whether you're replacing the outlet to match a new dryer cord or to repair a faulty plug, wiring the outlet is the same for them all and an easy procedure to complete.
Shut off the main circuit breaker to the dryer circuit. In the main breaker panel, the dryer circuit will be connected to a 30-amp breaker and typically labeled "Dryer." Test the wiring at the dryer location using a circuit tester to verify that no current is present in the outlet wire.
Remove the new dryer outlet's cover with a slotted screwdriver and identify the outlet's terminal labels, typically stamped as "L1" for line 1, "L2" for line 2, "N" for neutral and "GND" for the ground connector.
Extract the circuit cable from the dryer outlet box. Remove approximately 4 inches of the outer sheathing from the circuit wire, if applicable, and about 1/2 inch of insulation from each of the three coated wires using wire strippers or a utility knife. The fourth wire in the cable will be a grounding wire, either bare copper or insulated in green.
Loosen each of the dryer outlet's terminal screws with the standard screwdriver.
Attach the circuit wires to the outlet's connection terminals as follows. Connect the black wire to the "L1" terminal and tighten the terminal screw to secure the wire. Connect the red wire to the "L2" terminal and tighten the terminal screw to secure the wire. Connect the white wire to the "N" terminal and the bare or green wire to the "GND" terminal.
Position the dryer outlet's cover into place and tighten the cover screw to complete the outlet installation.
Turn the power on to the dryer circuit at the main breaker panel.