Can I use Flex-Jack in LAN ports that do not have POE available?
Yes. You can either use a mid-span power injector to insert power to that port or you may connect an external (wall mounted) power supply instead. Use only power supply provided by Chip PC!
Can POE cause fire? Can I get electrical shock from its wires?
No. One of the strongest features of the POE standard is the built-in protection against short circuit and over-current. The POE standard is not about "brutally" forcing power into the LAN it is a sophisticated and safe negotiation procedure with real-time safety measures. As soon as the PSE (Power Source Equipment) senses any deviation from normal behavior it will terminate the power to that port.
Can POE damage my existing (non-POE) devices connected to the LAN (like laptops)?
Certainly not! Before POE source provides any power to the LAN it tests the connected NIC to confirm (beyond any doubt) that it supports POE and the estimated power that it will consume.
If an external (wall-mounted power supply) is connected and powered - the device will continue to work normally. If POE is the only power source - the device will lose power. In either case no damage (software, settings or hardware) can resulted from an unscheduled power down event.