Hazard of Electric Shock: Remove all power from all devies before removing any covers or doors of the system. Disconnect power at the device and at the power source.
The C20 series cameras have the BNC and neutral ground for 24VAC tied to the same ground plane. This can cause a power supply short if the ground and hot are connected out of phase at the power supply. This can also cause ground loop bars in the video if connected to a supply that is not on the same ground plane as the camera. This also causes problems with some third party UTP brands connections.
C20 cameras connected to common power supply and/or ground planes that are different.
The 24 VAC on the C20 cameras are connected to a common ground plane and the BNC connection is grounded to the same ground plane
When installing the C20 cameras use single isolated transformers for each camera, or make sure the wiring is tied with the same phase. This is done by making sure the same wire leg of each camera is connected to the same wire side of the transformer on the power supply. Also when connecting to the power supply use a meter to test for voltage potential differences. Check that the cameras will work with the third party UTP brand you are using