Hello, if you look at the specifications of your cameras, the label attached to them tells you the consumption. In general for analog cameras including HD and FULLHD with night vision through LEDs up to a range of 20 meters is 500 m per camera. That is to say in a standard cameras is that consumption. I handle these calculations and if the feeding is done correctly, without going out of the rules you will not have problems. My criteria do not bring power from a source to more than 20 meters and with a specific cable for it (I do not use a UTP pair except in cases of only one camera and in a section less than 10 meters). Then there are cameras that consume more and they will specify it on the labels, such as some IP WI or cameras with IR LEDs with a range of 40 meters. But performing the installation of the power supply within the standards and with "common" cameras calculate 500 ma post camera. NOTE: The biggest problem of bringing power beyond what the source cable gives you is not solved by increasing the amperage, since the problem is the voltage drop and not the current. Regards.