Colours and ratings of house wires
Show on a big screenA house has three wires. Their covers are not all the same colour.
- A house has three wires: live, neutral and earth.
- Your book gives red for live, black for neutral, green for earth.
- A flexible cord may use brown for live and blue for neutral. An earth wire may be green and yellow.
Loading lab…
Read the colour. Tap the wire it marks.
The rule
Your book gives red for live, black for neutral, green for earth. A flexible cord may use brown for live and blue for neutral. An earth wire is marked green and yellow in Indian standards.
A colour does not make a wire safe. Do not touch bare mains wires. Do not open sockets or switch boards. Only a trained electrician works on real wiring. Ask an adult.
A circuit's rating is the most current it should carry.
Your book says a house often has two circuits. One is 5 A, for bulbs and fans. One is 15 A, for geysers and air coolers.
Worked example
Your book uses 220 V. A geyser is an electric water heater. It uses 2500 W.
Here I is the current in amperes (A). P is the power in watts (W). V is the voltage in volts (V).
I = P ÷ V = 2500 ÷ 220 = 11.4 A
That is over 5 A and under 15 A. So your book puts the geyser on the 15 A circuit.
A fan uses 60 W. I = 60 ÷ 220 = 0.27 A. That is well under 5 A. A 5 A circuit is enough.
Watch out!
A colour is a guide, not a guarantee. Cords and fixed wiring can differ. IS 1293 is the Indian plug standard. It also lists 6 A and 16 A ratings. The idea is the same: a bigger load needs a bigger rating.
Try the lab to finish this lesson.