Hot & Neutral Wires in Dryers

240-Volt Circuits

• A power line transformer acts as a 240-volt AC generator. It connects to the residential service panel by means of two hot wires, one red and one black, that have that voltage between them. The generator oscillates at 60 Hz, which means that the polarity changes 60 times per second, so the two wires are 180 degrees out of phase. This means that when one of the hot wires is positive, the other is negative, and vice versa. When the two wires are connected, they form a complete circuit, and any 240-volt appliance connected by only these two wires will operate normally.

120-Volt Circuits

• Most lights and small appliances in a typical residence run on 120-volt power, and it is supplied by one of the hot wires from the panel. In order to form a circuit, however, the electricity must somehow return to its point of origin, which is the function of the neutral wire. A tap from the transformer connects to the neutral bus on the panel, and all wires leading from this bus, which are always white, provide a path back to the electrical source. The neutral wire essentially splits the voltage between the two hot wires in half.

Electrical Requirements for a Dryer

• The element on an electric dryer heats by electrical resistance and needs high voltage to reach the temperatures necessary for drying clothes quickly. This high voltage is supplied by both hot wires from the panel, but it isn't needed to run the other electrical equipment in a typical dryer, such as the tumbler, the lights and the timer. Those auxiliary circuits run on the 120-volt power supplied by one or the other of the hot wires, and a neutral wire is needed to complete the 120-volt circuits. Dryers also have a ground wire, which is a safety precaution.

Dryer Wiring

• Modern dryers have four electrical terminals. They include two brass ones for the hot wires, which are red and black. Usually centered between the brass terminals is a silver one for the white neutral wire, and below it there is a green terminal for the ground wire. Because the neutral wire is bonded to ground at the panel, the electrical code didn't previously require a separate ground wire, so older dryers have only three terminals. It is possible to use an older dryer on a grounded circuit, but you must physically connect the machine to the ground circuit by means of a grounding screw attached to its body.