Just doing a simple junction box, connecting old, existing wire to new wire in a kitchen renovation. The old wire has only got a black and a white wire, no ground, and I want to connect it to 12/2 romex NM which obviously has a black white and ground wire. I understand the black gets connected to black, and white to white, but what do i do with the ground wire? was i supposed to use a metal box and connect the ground wire to that? Probably a stupid question, but thanks in advance for all replies.