Replacing Blown Fuses

REPLACING BLOWN PLUG FUSES:
The first step is to turn off all lights and appliances on the circuit controlled by the fuse. Then turn off the main power. In newer houses, the main power is controlled by two boxes that are equipped with cartridge fuses. To shut off the main power so you can safely remove the blown fuse, grasp the handles of the cartridge boxes, one at a time, and pull the boxes from place. In older houses, the main power is controlled by a lever type switch on the side of the fuse box. To cut the power, pull this switch downward.

Actual fuse replacement is simple, but use care when working at the panel.

1. Select a fuse rated for the same amperage as the one you are replacing.
2. Turn the blown fuse counterclockwise to remove it from the fuse box.
3. Install the new fuse by screwing clockwise into the socket.
4. Replace the main fuse boxes or turn the main power on.

REPLACING FAULTY CARTRIDGE FUSES:
To determine if a cartridge fuse has failed, proceed as follows:

1. Turn off the main power and open the service panel of the fuse box.
2. Using a fuse puller, grasp the middle of the fuse and pull it out of the spring clips that hold it in place. If the fuse has knife blade ends, don't bend them.
3. Some cartridge fuses are mounted in a compartment-type housing (Fig. 8). To remove the fuses, grasp the wire-loop handle and pull the compartment straight out of the panel.
4. To test the fuse, touch one probe of a continuity tester to one end of the fuse and the other probe to the other end. If the tester lights, the fuse is okay. If the tester does not light, replace the fuse.
   CAUTION: Never test a fuse while it is in the service panel. Always remove it from the service panel.
5. To install a cartridge fuse, push it into the spring clips by hand. If a new fuse fails, the problem is in the circuit wring or there is a short circuit in an appliance.