If you have an isolated power outage, such as a light suddenly going out or the microwave stops cooking, the problem is likely a blown fuse. You can changes blown fuses in a Wylex fuse box (most popular in the United Kingdom, but also found elsewhere) and brighten up the room, or finish cooking dinner. Wylex boxes use MCB's (Miniature Circuit Breakers), also known as fuses.
Unplug the malfunctioning appliance and test it by plugging it into another electrical outlet to make sure the appliance itself is not defective.
Locate the fuse box and cut the power to the entire house by turning the main switch to "OFF."
Pull the fuse directly out of the base. Take the old fuse to the hardware store when you purchase the new fuse to make sure you get the correct replacement fuse.
Remove the MCB base by undoing the small screw that is visible once you remove the faulty fuse.
Turn the master switch to "OFF" on the new fuse. Insert the fuse into the base. Turn the master switch on the new fuse to "ON." Leaving the fuse in the off position prior to inserting it in the base may prevent the fuse from prematurely discharging.
Reconnect the power to the house by moving the master power switch to the "ON" position.
Ensure that the power is disconnected before changing the fuse. Failure to disconnect the power before changing the fuse can result in electrocution.