A wire ampacity table is a chart displaying the electrical amp rating carried by specific wire types and gauge sizes. Amperage is a measure of the electrical current flowing through a circuit, which is measured in amps. Proper wire size must meet specific amp limits.
A wire carrying a current beyond its amp limitations can overheat and become hazardous. For example, 14-gauge copper wire can carry an amperage load of up to 15 amps, while 12-gauge copper wire can carry a 20-amp load. Aluminum wire in a 12-gauge size is limited to a 15-amp load. Proper wire size is determined by American Wire Gauge standards and enforced by the National Electrical Code.