Have an existing light fixture junction box. Want to add a gfi receptacle about 10' from the box. The existing wire in the box is 14/2. Can 12/2 wire be used from the box to the gfi receptacle? Thank you.
It can, but why put yourself through the pita of wiring anything with 12ga if you don't have to. I"m guessing you have some laying around. What it could do however if anyone opened up that GFCI and saw the 12ga they could assume that the circuit is a 20 amp. Not a big concern, just sayin'.....
Do you want it your way or the right way?