Moving outlet in bathroom remodel

Terry, I have eliminated a knee wall during our bathroom remodel. The knee wall was adjacent to the old vanity and housed an outlet next to the sink. I have rerouted the wires from their original entrance in the subfloor to the subfloor hole that accommodates the vanity drain stack. I don't have enough wire to do anything other than a junction box and then extend that to a new electrical outlet above and to the right of the new vanity. I have two questions. Firstly, can I install a junction box in a GFI circuit ? Secondly, is it ok to route the wires and J box next to the drain stack.
Thank you in advance.
Tom

 

Yes, you can use a box for the GFCI circuit as long as it will be accessible. You cannot bury a box behind drywall, tile, etc. Yes, you can place the box near the drain stack. If it's a metal box, just don't have it touch any metal pipes. A bathroom GFCI receptacle must be within 3' of the edge of the sink itself.