How to Remove a Cartridge Fuse. Cartridge fuses are not as readily found in most modern homes, but they are still used in many homes as a means of disconnect for certain electrical appliances like your central air conditioner. If you ever find yourself in a situation where you need to remove a cartridge fuse to either test it or replace it, here's how to do it.
Before you begin, turn off the power to the disconnect box before you open it. The breaker will be located in your main electrical panel.
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Once you have the power off, turn the disconnect switch OFF and open the cover of the disconnect box. Most disconnect boxes have a hinged door that swings open and then slides back, so it stays open. Inside the disconnect box you will see the line and load wires and the cartridge fuses.
Use the voltage tester to test the circuit for power. Touch and hold one probe tip to the grounding screw and then touch each of the line terminals with the other probe tip. If you get no readings on any of them, the circuit is off and you're safe to proceed.
You will notice that the cartridge fuse puller has pullers on each end, but they are different sizes. Use the smaller size clamp for pulling the fuses.
Open the clamp and position it around the center of the fuse. Pull the cartridge fuse out of the two clamps that are holding it.
To insert a new fuse, simply reverse the directions. Hold the fuse with the puller clamp in the middle of the fuse and gently push it into the clamps that hold it. You want to ensure that the copper clamps are contacting the copper ends of the cartridge fuse.
Pull the cover toward you to release it and then lower and close the cover door.
Do not turn the disconnect switch back on just yet. Go to the main electrical panel and turn the breaker back on first, then go back and turn the disconnect switch back on.