The APC P7V Audio/Video Surge Protector with 7 outlets warns you of immediate wiring issues such as improper grounds that could cause damaging shocks. This APC P4V reduces line noise that can cause data loss and keyboard errors. The SurgeArrest will warn you if its circuitry has been damaged by heavy strike or power line surge and if it is unable to provide 100% protection. In addition, APC's SurgeArrest is fail safe, which means that once the circuit of an APC SurgeArrest has been compromised the unit disconnects equipment from the power supply ensuring that no damaging surges reach your equipment.