I am installing a security camera system in my business and need to know if the video and power cables need to be in conduit or not. The building is open face brick and the power for the cameras is 12v 350ma.
Probably not, if is a Class 2 or 3 power supply. However there are other issues, such as:
Are you running the cables thru a suspended ceiling - it may require plenum rated cable.
Splices have to be accessbile
Riser cable is required in walls
You won't get correct answers from a radio depot type of store. Contact a low voltage contractor. Also you may need permits and inspections.
this is a pretty common scenario. keep in mind that 12vdc does not go very far before the voltage drop causes problems on your circuit. if you are considering conduit, then you should really ask someone that knows to take a look at your installation and see if you have all the bases covered.