Hello. I'm planning on installing a gfci outlet on my front porch. There is a plug on the front exterior wall of my living room that has the porch light tied into it and that is it. It is a 20 amp circuit. The location where I want my porch plug will be in the same stud bay as the interior receptacle. Can I pigtail off of this plug with 12/2 wire or will I need to make a homerun to the panel. I really don't want to run a new line to the panel because I only have 15 ft of 12/2 wire and the panel is on the other side of my house. The only thing plugged into the interior plug is a table lamp.