A POE (power over Ethernet)-prioritized active splitter is disclosed for a prioritized network having different priorities such as a network security system that uses an intelligent POE power supply with a prioritized back-up response, allowing a lower cost UPS (uninterruptible power supply) system to be used, and also providing a longer back-up time period by the UPS system for more critical components of the security system. A simple embodiment operates with only two priority levels, a high priority level for more critical components of the, such as the cable modem, the system router, fire alarm devices, local warning devices and the alarm communicator, while less critical components are supplied with electrical power at the low priority level. In the event of a power outage or disconnection, the critical high priority components remain connected to the Ethernet network to be supplied with electrical power by the UPS system and also to communicate over the twisted wire pairs of the Ethernet network.