The gauge lets you know the thickness of wire. The higher the wire gauge number, the thinner the wire in diameter. Lower wire gauge numbers result in thicker wire. Thicker wire can take more electrical current than thinner wire without becoming too hot. In the U.S. and Canada, we measure wire by the American Wire Gauge standard, or AWG. When you know the wire gauges for your appliances, such as your electric dryer, you help prevent the possibility of fires due to undersized electrical wiring.
Electric dryers commonly use from 20 to 30 amps of power. An amp represents a unit of electric current. The number 10-gauge copper wire exists as the only gauge used for devices that must have a maximum of 30 amps. Labeled on the outside of the wire covering, you will see the gauge number and another number. For example, you may see 10-3 written on the cable covering. The "10" represents the wire thickness, a 10-gauge wire, and the "3" means the cable has three 10-gauge wires inside, plus a grounding wire, which may not be listed on the covering.
The copper wire size or gauge you use also depends on the circuit breaker capacity in your home. Each circuit breaker has a rating for the wire type and amps needed by its circuit. Locate the amp rating as a number stamped on the breaker switch end, such as 15 amps for a standard breaker or 30 to 50 amps for large capacity breakers. Since your electric dryer has its own large capacity breaker using 30 amps, the only exception to using a 10-gauge wire will be if your dryer needs a long run of wire, such as 100 feet. Then you can use the next larger size, an 8-gauge wire, to avoid a drop in voltage.
Because copper wire has so many advantages over aluminum wire, which was once commonly used in home wiring, your electric dryer uses copper wire. Unlike aluminum, copper wire will not corrode. Copper resists corrosion from humidity and moisture, which are common around laundry.
Although aluminum wire may cost less to install, over time copper wire saves you money, mainly because it installs effortlessly without you having to buy extra tools or connectors. You also save money, since you do not need to make calls for repair or maintenance because copper always provides ideal performance and strength, copper resists breaking and stretching and copper carries current more efficiently than any conductor of electricity. (See Reference 4)
You will find the 10-gauge, copper electrical wire for your electric dryer insulated in a sheath or cover made of rubber, plastic, fiberglass or enamel. This covering prevents electrical shorts from occurring. An electrical short happens when heavy electric current flows until the fuse blows or the circuit breaker trips, which quickly cuts off the current flow; otherwise, a fire can happen from overheating.