However, a hairdryer uses about 1,200 watts. A refrigerator uses about 350 watts and a large microwave uses about 1,800 watts. The point here is that each and every circuit in your house should be constructed to handle the lighting or appliance that will be using it. Every circuit should be built with each component having the same amp rating. As discussed above, 14-gauge wire has an amp rating of 15.
Thicker wires can carry more amps.
For instance, 12-gauge wire has a rating of 20 amps, providing a capacity of 2,400 watts at 120 volts. Breakers, fuses, switches and outlets all come in varying amp ratings to match the wiring. When installing a circuit with a specific amp rating, you should make sure that you use wire, a breaker or fuse, switches and outlets that all have an equivalent amp rating. Now that you have an understanding of how to calculate the load and the requirements of a circuit, you can map out and interpret the electrical system in your house. Begin by drawing a floor plan of each floor of your home.