T1 Surge Protective Devices (SPDs) are installed at the service entrance to safely discharge high-energy lightning currents (10/350 μs) and protect electrical systems. Dual-rated for T1/T2 applications, they are mounted in the primary distribution board and must be coordinated with T2 devices for complete protection. T2 SPDs, installed on the load side or in sub-distribution boards, discharge 8/20 μs surge currents and protect equipment from transient overvoltage using MOV technology.