installing outdoor electrical socket

Hopefully a simple question, but I am a simple person. I am attempting to install a duplex socket on an exterior wall. The wiring was installed by the prior owner. There is a ground wire, white, black and red wires. When I connect white to silver, black to brass and ground to ground, leaving the red wire disconnected, but topped with a wire nut, I have power. What am I doing wrong? What should I do with the red wire? Thanks in advance.

 

Where was this wire? Is the other end of the wire attached to anything? If the wire was just loose in the wall then it should not have been attached at the other end.

 

Thanks for the quick response. The red wire came out of the wall, along with the white, black and ground wire. The end is connected to a wire nut.

 

Sounds like your new receptacle is working, so I'd just call it good. There are many possible explainations for the red wire. Perhaps the person who ran it had 14/3 but no 14/2 on hand. Perhaps it is part of a multiwire circuit, with the red wire another hot wire on the other power leg. Perhaps the red wire is controlled by a switch somewhere, and the person who ran it intended to make half of the receptacle switched.

In any of the above cases, capping off the red wire is a fine solution. There are some less likely explanations, but they're not worth speculating on without further investigation. If you're going to lose sleep over it, trace that red wire back and see where it goes.