Question

Explain the significance of kWh meter, main switch and main fuse in house-circuiting.

Answer 1

The electric cable coming to a house consists of three separate insulated wires, namely, live (phase) wire, a neutral wire, and earth wire. The neutral and earth wire on the supply end are connected together so that both of them are at zero potential.
Inside the house, the live and neutral wires are connected to the input terminals of kWh meter, while the earth wire is connected to the body of the kWh meter. The kWh meter-reads the units of electric energy (in kWh), consumed in a house. Without the kWh meter, it is not possible to correctly note the electric energy consumed in a house or by an electric appliance.

The live wire coming out from the output terminal of kWh meter has another fuse in it which is called the main fuse. If the main fuse blows off the entire circuit of the house wiring system is disconnected from the mains supply.
Beyond the main fuse, the live and neutral wires are connected to the main switch which consists of a double pole iron-clad switch. This switch can cut off the live and neutral wires from the household circuit by operating a single lever. The iron casing of the main switch is locally earthed. Then the power flowing out of the main switch is distributed in house by the common ring or three-wire system. The diagram illustrates the working of the kWh meter, the main fuse, and the main switch.