Schneider Electric HEPD50 Surge protection device, HEPD, 50kA, 120/240 V, 1 phase, 3 wire, SPD type 1, UL Listed HEPD whole house devices are designed to deliver AC surge protection for the entire AC power system in a home. HEPDs are compact in size and are designed to protect AC wires in the home from surges that could affect home electronics and appliances not connected to surge strips. For use on 120/240 VAC single phase, 3 wire systems with an isolated ground. This device provides 25 kA of short circuit protection and 50 kA of surge protection per phase. The surge protection device is in a NEMA 4X housing. The surge protection device is 3.23 inches tall, 3.72 inches wide and 2.10 inches deep. The surge protection device is UL listed.