What causes faults and voltages in the network cable?

Installation errors, ageing processes, environmental influences or moisture can make cable sheaths brittle or fragile. The unwanted electrical connection to other live parts can lead to high overvoltages and voltage peaks for a short time and lead to a fault within the electrical system. Potential differences between the devices can also be a source of errors. If several devices are combined in one system, the leakage currents also add up. Whether leakage currents, short-term high overvoltages or voltage peaks, current always flows and also finds its way via the Ethernet data network.

An example from practice:
An isolating transformer was used to ensure electrical safety at a measuring station. By connecting the measuring station to a network (LAN), this electrical safety is invalidated. The reason for this is that the LAN connection was not electrically secured (isolated) via the network cable. If the measuring unit causes a fault, the isolating transformer prevents overvoltages or voltage peaks to the power grid, but not overvoltages or voltage peaks to the Ethernet data network. The complete system is only galvanically isolated when a network isolator is used.