Can I tap into an existing 12 gauge wire run on a 15 amp circuit (put in a junction box) and connect a 14 gauge wire to install an outdoor outlet? - Quora
15 amps wire size - All you need to know
Difference between 15 vs 15A Receptacle and Wire size - DoItYourself.com Community Forums
Guide to Electrical Wire Sizes
What is the size of a solid copper wire for a 40 amp breaker? - Quora