Physics - Electricity and Wiring

Electrical hazards

Electricity is a useful form of energy but it can also be very dangerous. There are lots of ways in which we can be electrocuted including:

• touching frayed electrical cables 
• long or overheating cables
• damaged or incorrectly wired plugs
• allowing water or wet objects to enter plug sockets or touch frayed cables
• pushing metal objects into plug sockets

The plug

The cable

A mains electricity cable contains two or three inner wires. Each has a core of copper, because copper is a good conductor of electricity. The outer layers are flexible plastic, because plastic is a good electrical insulator. The inner wires are colour coded and have different functions:

Colour	Wire	Function
Brown	Live	Is held at a voltage of 230 V and provides the current
Blue	Neutral	Completes the circuit
Green and yellow stripes	Earth	A safety wire to stop the appliance becoming live

An earthed conductor cannot become live.

The wires

In a plug, the blue neutral wire goes to the left, the brown live wire to the right and the green and yellow striped earth wire to the top. The fuse fits next to the live wire.

The diagram shows the key features of a three-pin mains plug:

Where does each wire go?

There is an easy way to remember where to connect each wire. Take the second letters of the words blue, brown and striped. This reminds you that when you look into a plug from above:

• blue goes left
• brown goes right
• striped goes to the top

(All information courtesy of BBC Bitesize)