If your digital video security and surveillance system has 16 cameras, you will more than likely need to get a 16 camera power supply.  Unless your cameras are battery operated or PoE (Powered over Ethernet), they will require that a power line be run from a power distribution box or transformer to the camera.

There are two different types of 16 camera power supply, based on the type of current that is needed by the cameras.  It seems as though most cameras these days lean toward the low-voltage Direct Current or DC of 12 volts.  However there are still systems that exist that create 24 volts of AC current.  You CANNOT connect AC voltage supplies to DC cameras or DC voltage supplies to AC cameras with one exception.