1.) new system
& old cameras
When combining a new system with old cameras, you only have to POE injector (outlet) use. This is because old cameras have a connection for power and data. Therefore the signal of the new system has to be disconnected first.
2.) new system
& new cameras
When combining a new system with our new cameras, you do not have to use a POE injector. This is due to the fact that a POE switch is used in new systems, which directly supplies the power for the cameras via its network ports.