Domestic Electrical Wiring

In domestic electrical wiring, all electrical appliances like electric lamp, electric fan, fluorescent tube, etc. are connected in parallel with the mains supply line. All these electrical appliances are independently controlled by their own individual On / Off switches and they draw electric current from the mains supply line according to their requirement on the basis of their resistance value. The total current according to the requirement of all electrical appliances is supplied by the mains supply line and a safety fuse of the rated value according to the value of total current supplied is connected as the mains fuse in series with the mains supply line to avoid any accident due to occurrence of any short circuit and overload condition.

In the above electrical wiring system, Miniature Circuit Breakers (MCBs) are used instead of safety fuses. MCB is an electrical device which automatically switches off electrical circuit during any abnormal condition like overload and short circuit condition. In addition to the mains supply DP MCB, one RCCB (Residual Current Circuit Breaker) is used in series with the mains DP MCB to prevent electric shock. Four SP MCBs are also used for four individual parallel circuits so that any defect in one circuit will automatically switch off its individual MCB and it will not affect the working of other circuits connected in parallel.

Generally, red / yellow / blue color wire is used for phase / live connection, black color wire is used for neutral connection and green color wire is used for earthing connection. Green color wire, which is used for the earthing connection is directly connected to the center top earthing terminal of the three pin socket. Black color wire, which is used for the neutral connection is directly connected to the left hand side neutral terminal of the three pin socket. Red / yellow / blue color wire, which is used for the phase / live connection is connected through on/off switch to the right hand side phase / live terminal of the three pin socket.

In the above domestic electrical wiring, the following electrical accessories & electrical home appliances are used.

1) Energy Meter.

2) DP MCB.

3) DP RCCB.

4) SP MCBs.

5) Five Terminal Neutral Connector Strip.

6) On / Off Switches.

7) Three Pin Sockets.

8) Electric Lamps.

9) Ceiling Fans.

10) Fan Regulators.

Energy Meter :

The mains supply wires of phase and neutral are connected to the phase and neutral input terminals of energy meter and the output phase and neutral terminals of energy meter are connected to the input terminals of DP MCB.

DP MCB :

The input phase and neutral terminals of DP MCB are connected to the output terminals of energy meter and the output phase and neutral terminals of DP MCB are connected to the input terminals of DP RCCB.

DP RCCB :

The input phase and neutral terminals of DP RCCB are connected to the output phase and neutral terminals of DP MCB. The output phase terminal of DP RCCB is connected to the input terminals of four SP MCBs and the output neutral terminal of DP RCCB is connected to one of the five terminals of a neutral connector strip.

SP MCB :

The input terminals of four SP MCBs are connected to the output phase terminal of DP RCCB. These four SP MCBs are used for controlling four individual parallel wiring connections of four different rooms. The output terminal of each SP MCB is connected to the input terminal of each on / off switch. Here four on / off switches of each parallel connection are used for controlling the following electrical appliances.

1) The first on / off switch is used for controlling a three pin socket.

2) The second on / off switch is used for controlling first electric lamp.

3) The third on / off switch is used for controlling second electric lamp.

4) The fourth on / off switch is used for controlling a ceiling fan.

Three Pin Socket :

The phase / live terminal of three pin socket is connected to the output terminal of on / off switch. The neutral terminal of three pin socket is connected to one of the five terminals of a neutral connector strip. The earthing terminal of three pin socket is either directly connected to the earthing wire of the mains supply line or to one of the five terminals of earthing connector strip if it is used.

Electric Lamp :

One terminal of each electric lamp is connected to the output terminal of its on / off switch and other terminal of each electric lamp is connected to one of the five terminals of a neutral connector strip.

Ceiling Fan :

Fan regular is always connected in series with the fan to control its speed. The output terminal of ceiling fan on / off switch is connected to one of the terminal of fan regulator and other terminal of fan regulator is connected to one of the terminal of ceiling fan. Other terminal of ceiling fan is connected to one of the five terminals of a neutral connector strip.

Terminal Connector Strip :

Terminal connector strip is used for the common connection of neutral wires of all electrical appliances. Phase connection is given to one of the terminal of each and every electrical appliance by using individual on / off switches. Other terminal of each and every home appliance is connected to one of the five terminals of neutral terminal connector strip where the neutral wire of the mains supply line is connected to one of the five terminals of this this common connection strip. This terminal connector strip can also be used for common earthing connection of all electrical appliances which require earthing connection for the prevention of electric shock.

Mock Test On Domestic Electrical Wiring