APC by Schneider Electric Replaceable, Rackmount, 1U, RS232 Surge Protection Module

Data line surges make up an overwhelming majority of all surge induced damages where the equipment was thought to be already protected but had a back door such as a modem line unprotected. Network interface cards, in particular, can be destroyed by relatively mild spikes.

According to Ethernet standards (IEEE 802.3), non-AC network electrical hazards include Direct contact between components and power or lightning circuits, static charge buildup on cables and component, high-energy transients coupled onto the local cabling system (those induced by other cables which are installed in the general proximity of network cables or lightning within a mile radius) and potential differences (even from building to building, between safety grounds to which components are connected.)