What is the 10A fine-wire fuse in the Premium-Line surge protectors for? December 05, 2022 12:55 Updated It protects the built-in RF filter from overload. A defective fuse can be easily replaced. Related articles Is a surge protection device still functional after an overvoltage? Why is the internal thermal fuse not exchangeable? What does it mean when the green indicator light is off on surge protection power strips? How are our RJ-45 jacks assigned for surge protection? What does 4,500A / 15,000A / 30,000A etc. mean in the surge protection devices?