PoE (Power over Ethernet) clocks utilise the Power over Ethernet standard to receive power and data over a single Ethernet cable. The standard allows for data and power to be provided via a Cat 5/6 data cable from a powered switch to an end device. In the case of PoE clocks they receive time, power and data via a single cable. The accuracy of PoE clocks are maintained as they receive time updates from a NTP timeserver via the network cable. The synchronising timeserver can be on the local network, remote (via the internet) or via GPS (GPS SNTP timeserver). Typical accuracy of digital PoE clocks is within 200 milliseconds (0.5 secs for analogue clocks).
The total cabling costs of installing PoE clocks are lower as power points are not required for each clock. PoE clocks utilise the existing computer network infrastructure. Power over Ethernet clock systems are completely scalable from a single clock to several thousand clocks. If a powered switch is not available then the addition of the power to the cable is provided by utilisation of PoE injector.