Protects major appliances from catastrophic surges...even lightning. SEP-200 protects against electrical surges that can cause damage to major appliances including their sensitive electronic circuitry. Catastrophic failures and gradual component degradation can be caused by high voltage surges, which are generated by harsh weather conditions, external power problems, or day-to-day electrical component switching. Panamax also recommends using secondary plug-in protectors at the equipment you would like to protect.