You should have no problem using the Cat5 cable for a typical camera that would be installed in home.

If there were several hundred feet of distance between the camera and the power supply, you might need a little larger cable (like #18 or #16), but for the short distances you will probably be going, the #24 gauge in the Cat5 should be fine.

Also keep in mind that most cameras have a video output that normally requires a coax cable between the cameras and the monitor. You can use a pair in the Cat5 cable to transmit the video signal, but to do so you will need a “transceiver” at both ends of the cable.

Transceivers (sometimes called “baluns”) are sold by most of the suppliers who sell camera equipment. One major brand of transceivers is NVT.

Good luck with the project.

This is a very handy place for figuring what size wire can handle what amount of current depending on frequency of signal being sent. If your cameras are analog they could need a couple of amps. Basically a CAT5 cable uses 24 gauge solid core wire. I have run 2 Amps across them with no problem, but the current vs wire gauge table puts 24 ga at 1.4 Amps rating. If the camera is digital, then you shouldn’t have a problem as most I have seen use about 500 milli amps to run, including infrared cameras.

Knowing the specific camera you have in mind, look up the power requirements, and if the power needs are under 1.4 Amps. I’d say you could at least try it. I personally like to double my wire gauge for current requirements. Safety factor of 2 is best. Good luck.