What gauge wire is Christmas lights?
Similarly, can I use 18 gauge wire for lights?
The 18-gauge wire inside a lamp cord is rated for a maximum current draw of about 5 amps. That's more than enough for a typical 120-volt lightbulb -- or even several of them. If the same bulb runs on 12-volt power, however, you should upgrade the cord to 16- or even 14-gauge to avoid voltage drops and dim lights.
Herein, what's the difference between SPT 1 and SPT 2 wire?
The difference between SPT-1 and SPT-2 wire is the thickness of the insulation surrounding the copper wire. SPT-1 wire has a thinner insulation than SPT-2. 18/2, SPT-1 wire has an insulation thickness of . 030″ and 18/2, SPT-2 has insulation that is .
A 15-amp circuit can handle 1800 watts (15 amps x 120 volts). 20-amp circuit: Max 1,920 watts (80% of 2,400 is 1,920). A 20-amp circuit can handle 2,400 watts (20 amps x 120 volts).