Visual Testing - If the glass window on screw-in fuses is clear, you will be able to see whether the fusing element inside the box is severed. It may appear brown, cloudy, or black because of the melting fusing element.
Testing Device - With the help of devices such as ohmmeter and continuity testers, you can measure electrical resistance. For checking a screw-in fuse, keep one test lead to the end of the fuse and the other to the threaded side. Hold the test leads at opposite ends of the fuse to check whether the current is flowing through the fuse for the cartridge fuse