What is the Proper Hook-Up for Dryer Outlet Wires?

Electrical Requirements

• Electric dryers use electricity in a combination of 120 and 240 volts, and between 25 and 30 amperes of current. The outlet supplies the current using two hot wires and one neutral wire. The two 120-volt hot wires combine to form 240 volt current. One of the hot wires and the neutral wire supply the 120 volt current.

  The circuit breaker, the 10-gauge wires that supply the outlet, and the outlet are rated at 30 amperes.

Three-Prong Outlets

• Three-prong outlets were used exclusively for many years. The two colored hot wires connect to the "L1" and "L2" terminals inside the outlet, and the white neutral wire connects to the "W" terminal. The hot wire terminals are sometimes labeled "X" and "Y."

  The neutral wire serves as the ground wire for the dryer, in addition to the return for the 120 volt current. This configuration is safer than not having a ground, but not as safe as a separate ground wire.

  Three-prong outlets are not allowed in new installations and use is restricted to replacement only.

Four-Prong Outlets

• Four-prong outlets are the only style outlet allowed in new installations and have a separate terminal for the ground wire. Like the three-prong outlet, the hot wires connect to the "L1" and "L2" terminals and the neutral wire connects to the "W" terminal. The bare or green ground wire connects to the "G" terminal.

  Four-prong outlets offer an additional measure of safety against shock by providing a separate ground and neutral wire.

Dryer Cords

• A three-prong cord will only fit in a three-prong outlet and a four-prong cord only fits in a four-prong outlet. The red and black wires are the hot wires, the white wire is the neutral wire and the green wire is the ground wire.

  The wiring difference is inside the dryer's wiring box. A jumper wire or ground strap connects the metal dryer case to the neutral terminal for a three-prong cord. A four-prong connects in a similar fashion, but there is no jumper wire. The green ground wire connects directly to the dryer case to provide the separate ground wire.