hello, I have an electrical box in my basement that was installed for a future receptacle. There are 2 white wires going into the box. I am wondering if I should purchase a 15A or 20A; 125 volt receptacle for installation? I see that most of the electrical receptacles in my home have only one white wire and this one has two. Another electrical box in my basement which already is set up with a functioning receptacle has 2 white wires, but I can't detect if the receptacle is a 15A or 20A. I want to make sure I am connecting the correct receptacle and since I am not experienced with this install I am hoping to get some feedback and advise from the experienced electrical folks out there. thanks in advance.