Introduction
Electric air conditioners, clothes dryers and ranges can't use the 120-volt, 15-amp or 20-amp circuits that power our lights, computers and microwaves. They need 240-volt or 120/240-volt circuits with current-carrying capacities of 30, 40 or even 50 amps.
A 240-volt circuit has two hot wires and an equipment ground, which is a safe path for unintentional current to dissipate. A 120/240-volt circuit has two hots, a ground and a neutral wire, which allows the appliance to use both voltages. Sensitive electronics, like touchpads and timers, run on 120 volts, heating elements and condensers on 240 volts.
Here I'll show you how to wire a 120/240V, 30-amp dryer outlet that accepts a four-prong grounded plug. The National Electric Code (NEC) requires this configuration for new construction. If your home was built before 1996, you may have a three-prong dryer plug and a circuit without an equipment ground. That's perfectly OK, but here, I'll show you how to safely update the wiring.
Before starting the project, pull a new circuit to the dryer location. You need two hots, one neutral and an equipment ground. For a dryer protected by a 30-amp circuit breaker, that means a 10-3 non-metallic sheathed cable, with ground.
Call a licensed electrician to hook up your circuit breaker if you don't have experience with wiring projects. If you're confident in your skills, connect the power yourself. Always be safe when working with electricity. Use a multimeter or non-contact voltage tester before connecting or disconnecting any electrical wires, and call an electrician if you need help.
Tools Required
Materials Required
- 10-3 non-metallic sheathed cable
- 2-gang PVC "old work" electrical box
- 30 amp dryer receptacle
- Cover plate
