The rule of thumb when utilizing different gauges of speaker wire is: The longer the run is from your audio amplifier to the speakers the lower the gauge as it relates to the amount of ohms be put out by your audio device. For example:
22 gauge wire can be used for the following ohms/distances: 2 ohms/3 feet; 4 ohms/6 feet; 8 ohms/12 feet
10 gauge wire can be used for the following ohms/distances: 2 ohms/50 feet; 4 ohms/100 feet; 8 ohms/200 feet
Keep in mind that there are seven different gauges of speaker wire so the above is only an example.
Although it should be noted that speaker wire runs more than 50 feet should be avoided even if the cable size is adequate, as the longer the runs over 50 feet will greatly diminish the quality/fidelity of sound.