The MJ8-POE is designed to protect sensitive data-processing equipment connected to a PoE (Power over Ethernet) network from transient overvoltages. The MJ8-POE surge protector is deployed in signal network applications with data transmission speeds of up to 1000 Mbps. The surge protector is housed in a shielded enclosure with high quality shielded RJ45 jacks. The transient protection circuit is based on high energy gas discharge tubes (GDT) and a network of fast response silicon avalanche diodes (SAD) to achieve sharp clamping of very large surge events.