What Wire Do I Use for 120V

Household wiring for 120-V circuits is almost always 12- or 14-gauge copper wire, depending on the current load and length of the circuit. The diameter of the metal conductor in a 12-gauge copper wire is 0.0808 inches; of a 14-gauge wire is 0.0641 inches.

Should I use 12 or 14-gauge wire outlet?

What Size Electrical Wire Should I Use When Wiring an Electrical Outlet (Receptacle)? For a 15-Amp circuit use #14 copper wire (or #12 copper-clad aluminum wire). The fuse or circuit breaker feeding this circuit is rated for 15 amps. For a 20-Amp circuit use #12 copper wire (or #10 copper-clad aluminum wire).

Can you run 120v through 18 gauge wire?

The resistance of 18 AWG copper wire is 0.0064 ohms per foot. If you apply 120v from a sufficiently robust power supply end to end on a one foot long piece of such wire 18,750 amps will flow until the wire gets hot enough to melt.