Electricity meter and fuse boxes on a wall in a house. The meter, black box on left, measures the amount of electricity used. It displays this information on a cylindrical number display, black and red, in kilowatts per hour (kWh). The two large silver boxes, at centre and right, are fuse boxes. Fuses protect electrical devices from excessive currents. Each separate circuit in the house has its own fuse. At a specific current the fuse will 'blow', breaking the circuit. These are old-type fuse boxes, with re-wireable fuses.