I bought new outlet for my living room that has a couple USB ports in it. The standard outlet I'm removing had 3 wires connected red, white, black). But the new one only has 2 connections. How should I wire it? Use white and black, then cap the red?
Look at the side of the original outlet the connecting tab is probably broken on the hot side. If you don't mind not having a switched outlet I would cap the red and you should be fine. Normaly the red is the switched connection but not always. If using the black the outlet is still controlled cap the black and connect the red to the outlet and you would be good to go.
With the power off, grope around in that hole. See if there are significant voids to the left and right of the hole. It looks an awful lot to me like you have a 1-gang mud ring centered on what is probably a 4x4" square metal box.
With a bit of careful drywall surgery, you could dig out that 1-gang mud ring and replace it with a 2-gang mud ring (be careful to select one of the correct/same depth). Now you would have space for two things abreast:
- A regular receptacle that is Decora (rectangular opening on the cover)
- The USB+receptacle
You could then hook the red and white wire to the plain receptacle, both its sockets are now switched (or you could split it, with a bit more work and a pigtail). On the USB receptacle, connect black to hot, and a white #12 pigtail that goes over and picks up neutral off the regular receptacle. #12 because you didn't say if it's a 15A or 20A circuit.
Add an oversize cover plate (this is easier found in 2x Decora) to cover up any drywall mistakes. Done.