3 Modes of protection (L-N : L-G : N-G) - The remaining modes continue to provide protection in the event a mode of protection is compromised as a result of a surge. LED Building Wiring Fault Indicator - This LED informs users of potentially dangerous wiring problems in the wall circuit. Always on Outlets - 8 outlet models offer dedicated space to accommodate wide transformer blocks without covering adjoining outlets and 2 always on outlets. You can plug 8 power cords including 3 transformers at the same time. In case you have equipment that has to stay on all the time, such as fax machine, you can plug it in always on outlets. The equipment will be protected and will have power supply even when the unit is switched off. Catastrophic Event Protection - SurgeArrest components such as MOVs and Thermal fuse ensure instantaneous reaction to lightning strikes and wiring faults. If the surge components are damaged due to power spike or over voltage, excess power cannot reach your equipment. Unlike the APC SurgeArrest products, most surge suppressors continue to let power through even after circuits have been damaged, leaving your equipment exposed to other damaging surges. Computer compatibility - The "Power-Saving Outlets" feature will work regardless of whether a desktop computer, laptop or netbook is used as the "Master" device. EMI and RFI noise filtering - Reduces line noise that can cause data loss and keyboard errors. Fail Safe Mode - Most other surge suppressors continue to let power through even after their circuits have been damaged, leaving your equipment exposed to future surges. APC's SurgeArrest 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. Lightning and Surge Protection - To prevent damage to your equipment from electric power surges and spikes. Power-saving outlets - Automatically cuts power to idle equipment to conserve electricity.