I've been using it continuously for about 5 months between 500w and 1200w steady use. This device seemed very stable up to 1500 watts usage. Anything above that will immediately disable the block. Second, I had to use an AVR (Automatic Voltage Regulator) as this device tends to put out <100V on reset when an inductive load is "overloaded". Otherwise it made things run smoothly. The last straw - one of the fans failed and this resulted in overheating, resulting in endless errors, shutdown, power-up (under-voltage), errors, etc.