Please help. I'm trying to replace an outlet. The one I'm talking off is a two prong outlet and the bottom is switched. There is no ground, there is a white, a black, and a red. I think I'm right that it's a line outlet, right? I'm trying to put in a GFCI and I don't know where to put the red. I hope that's clear enough. Thanks in advance!
There are three wires coming into your old configuration:
- always-hot (used on the always-on half of the receptacle)
- switched-hot (used on the switched half of the receptacle)
Code says that if neutral is present (it is), then it must be white. So the white ought to be neutral. Code does not mandate the other two be any particular color. Either could be either one, but some electricians like to use black for always-hot and red for switched, in a case like this.
Your GFCI+receptacle combo device requires two wires:
As you can see, the switched-hot wire is useless. Cap it off with a wire nut, then tape the wire nut on so it doesn't come off. Do not cut the wire back, you cannot insulate it if you do, and the next owner may want to use it.
The red is probably the switched leg which went to the bottom of the old outlet.
Just cap it off safely with a wire nut and leave it.
Since you don't have a ground wire on your new GFCI, you should label it "No Equipment Ground" (and your new GFCI probably came with some pre-printed labels for that).