Testing Cartridge Fuses

What is a Cartridge Fuse?

Cartridge fuses come in a cylindrical shape and have contacts points at each end. They have a fuse link connected to the two ends and are rated for 240-volt circuits and protect the circuit from over-current. The Ferrule-type fuses are rated up to and including 60 amps. It’s big brother, the knife-blade cartridge fuse, is similarly shaped with blades on each end. The difference is that they protect circuits above 60 amps up to 600 amps. All of these fuses can be installed and removed by using a special tool, a fuse puller. It mimics the shape of the fuse and snaps over the fuse for easy removal. It is usually made out of plastic.

Removing a Cartridge Fuse

In order to test a cartridge fuse, you must first remove the fuse holder from the electrical panel. Grab the handle and pull straight out from the panel. Stand to the side of the panel when pulling the fuse holder and it is advised to wear safety glasses. Now remove the fuse using a fuse puller. Set the fuse on a table or work bench for easy testing.

How to Test a Cartridge Fuse

In order to test a cartridge fuse, get a multi-meter out and place it on your work bench. Turn on the tester and turn the dial to ohms on a lower setting. Place one lead in each hand and touch each to a different side of the fuse. If the fuse is good, the tester should have little or no resistance showing on the meter. If the fuse is bad, you’ll see an infinite reading, meaning the fuse link is blown.

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