Surge Arrest components such as MOVs & Thermal fuse ensure instantaneous reaction to lightning strikes & wiring faults. If the surge components are damaged due to power spike or over voltage, excess power cannot reach your equipment. Unlike the APC Surge Arrest products, most surge suppressors continue to let power through even after circuits have been damaged, leaving your equipment exposed to other damaging surges. This LED informs users of potentially dangerous wiring problems in the wall circuit. Catastrophic event protection Surge Arrest components such as MOVs & Thermal fuse ensure instantaneous reaction to lightning strikes & wiring faults. If the surge components are damaged due to power spike or over voltage, excess power cannot reach your equipment. Unlike the APC Surge Arrest products, most surge suppressors continue to let power through even after circuits have been damaged, leaving your equipment exposed to other damaging surges. Building wiring fault indicator This LED informs users of potentially dangerous wiring problems in the wall circuit. Protection working indicator Surge Arrest will warn you if its circuitry has been damaged by heavy strike or power line surge & it is unable to provide 100% protection. Catastrophic event protection Surge Arrest components such as MOVs & Thermal fuse ensure instantaneous reaction to lightning strikes & wiring faults. If the surge components are damaged due to power spike or over voltage, excess power cannot reach your equipment. Unlike the APC Surge Arrest products, most surge suppressors continue to let power through even after circuits have been damaged, leaving your equipment exposed to other damaging surges.