what is the difference between 12/2 and 14/2 electrical wire?
12-Gauge Vs 14-Gauge Wire A standard 12-gauge copper wire has a diameter of 2.05 mm, while the diameter of 14-gauge copper wire is only 1.63 mm. If you're wiring a circuit on which there are both lights and outlets, or you just aren't sure which wire gauge to use, you can't go wrong by choosing a 12-gauge wire.