Produced by Southwire Co., Romex is a line of nonmetallic sheathed cable or NM cable. NM cable is the wiring material used for residential electrical supply, including heavy-duty appliances such cas clothes dryers. To simultaneously produce intense heat, tumble a drum and run a timer, clothes dryers require special wiring. Although most projects call for a standard wire size, certain circumstances will affect your choice. For example, because amperage drops over distance, you might have to increase your wire size if the dryer is far from its electrical source.

Clothes in dryer
credit: Jupiterimages/Comstock/Getty Images
Energy-hungry electric dryers require special outlets and wiring.

About Romex and NM Cable

Romex is an old product line and many builders use the word "Romex" to refer to all brands of NM cable. However, all brands, including Romex, are suitable for residential wiring applications, such as running clothes dryer circuits. NM cable consists of several insulated copper wires sheathed in a plastic insulation. The minimum number of wires in an NM cable is three: one hot wire, one neutral wire and one grounding wire. Like other metal products, manufacturers refer to wire size or diameter in terms of gauge. Gauge is represented as a number; smaller numbers indicate thicker wires.

Wire Gauge for Clothes Dryers

Clothes dryers require a relatively thick wire to accommodate their 30 amp circuit. The minimum recommended wire size for clothes dryer circuits is 10 gauge. However, amperage decreases over distance, so appliance manufacturers advise a larger wire gauge for circuits that extend beyond a distance from their source. In general, a circuit that runs 15 feet to reach the dryer requires larger wire, usually 8 gauge. Despite manufacturer recommendations, you should check with your local building department to determine exact wiring requirements. Local building codes always have the last word.

Cable Type for Clothes Dryers

Standard electrical clothes dryers have unusual electrical requirements. They usually need 240 volts to perform heavy-duty work and 120 volts to power timers and controls. To achieve both tasks at once, the dryers need two hot wires. Because every NM cable, including Romex, has a ground wire and neutral wire, this means that your cable must have a total of four wires. Cable manufacturers exclude ground wires from the cable count, so when you purchase your clothes dryer cable, it will be labeled as three-wire cable. Manufacturers name cable according to its wire gauge followed by the number of cables. For example, for installations under 15 feet, your product's label will read "10-3 NM cable." If your installation requires 8 gauge wire, you'll need "8-3 NM cable."

Wiring Clothes Dryer Outlets

Cable is only one piece of the clothes dryer wiring equation. For a successful installation, you'll need the right outlet and a suitable circuit breaker. Remember that dryers require dedicated circuits, which are circuits that serve only a single fixture or appliance. The dryer requires a 240 volt outlet; these have relatively large, unusually shaped plugs. The breaker ranges from 30 to 50 amps and typically has two poles that provide 240 volts. Wiring breakers and outlets is dangerous. Small mistakes can lead to serious property damage or personal injury. If you're unsure how to complete the project, consult an expert for assistance.