A device that provides surge protection for network cables carrying data. Data line protectors prevent voltage spikes and surges from damaging costly hubs, switches, routers, and other devices. They are essentially surge protectors that are placed inline between stations on the network and concentrating hubs or other devices in the wiring closet.
Data line protectors are available from different vendors for virtually every kind of networking connection, including RJ-45 connections for Ethernet networks, RJ-11 connections for telephone lines, and RS-232 connections for serial lines.
You connect a data line protector directly to one of the two connected devices, and then you attach the ground wire to a good ground connection so that there will be a path for voltage surges to flow down. For Ethernet networks using unshielded twisted-pair (UTP) cabling, data line protectors are available with multiple ports that are attached directly to the hub or the switch.
Additional 10BaseT surge protectors can also be installed directly on the stations on the network for more protection.
Graphic D-4 - Data line protector.
Most newer hubs, switches, routers, and other networking devices include built-in data line protection circuitry, which eliminates the need for additional data line protectors.