I am replacing an old outlet with a GFCI and I have encountered a red wire...what is the red wire for?
There might be a three way switch on the circuit,or a red wire can indicate a second hot wire. It gets complicated very fast, however almost all homes have these red wires in them, and they serve an imporatant service. Could be a red wire is used when you come out of a switch with hot and go into another switch as neutral.
How To Connect Gfci Outlet
Just loose in the box or was it connected to the receptacle? If connected, it could be a switched wire to control half the receptacle. That won't work with a GFCI receptacle. Wire nut it off in the box.
It sounds like that receptacle was half switched. Receptacles are designed to have the small brass tab on the black side snap off and one half is constantly alive (black wire)and the other side is connected to a wall switch (red wire). Is this in a room with no ceiling light? Switched outlets are usually for a lamp to turn on as you enter the room. GFCI outlets are not designed to be switched on and off as both sides will go off. Is this room in a basement, kitchen, bathroom or near water pipes? You may not be required to have it GFCI protected. If you can and want a GFCI then try another outlet near by.
In general, bare copper wires are ground, white are neutral, and black or red are hot. Make sure all wires are completely separate from one another, and then turn the power back on. Be careful not to touch any of the wires. Use your voltage tester to find the incoming hot wire. The wire should be black. The white wire in the same cable will be the neutral. Additional white and black (or red) wires will be extensions of the same circuit test them as well.
