Brown wire is live, blue is neutral, and green/yellow is earth. The earth wire protects users from electric shock by providing a path for current to flow if the live wire touches exposed metal. Double insulated appliances do not need an earth wire because their metal parts are covered with insulating plastic.

1. Wiring a plug
Appliances are connected
to the main ring using 3-
pin plugs: two short pins
and one longer one.

2. The wires and pins must always be connected in the same
way, so they made the wires in the connecting lead are
colored code.
The wires and pins must always be connected in the same
way, so they made the wires in the connecting lead are
colored code.
Brown = live Blue = neutral Green/Yellow = earth

4. If you touch a live wire at about 230V,
an electric current can pass through
your body, which will cause electric
shock and you can be killed. That's
why ring-mains and lighting circuits
have an earth wire, to protect
ourselves.
Earthing

5. 12
3
4
to light bulb
to light bulb
5
6 7
8 9

6. Explanation
1
2
3
4
5
6
7
8
9
one end of the earth
wire is connected to
the metal base of the
lamp...
... the other end is
connected to the
earth pin in the plug
a wire leads from
the earth pin in the
socket...
... to a metal plate
buried in the earth
metal base
path of current
bare live wire touches case
The current normally flows to and from the
light bulb along the live and neutral wire
If the insulation wears through, the current
flows through the metal to the earth wire

7. 12
3
4
to light bulb
to light bulb
5
6 7
8 9

8. Residual current circuit
breakers
A residual current circuit breaker can be used to
protect against a fault which makes the outside of
a properly earthed appliance become live, and
where the current in the earth wire is not enough
to blow a fuse (this can be very dangerous).
A residual current circuit breaker contain an
electromagnetic switch in order to quickly turn off the
power if the current in the earth wire is bigger than
0.03A.
Circuit breakers like this are recommended for use with lawn
mowers, portable tools (electric drill), and school laboratories.

9. No earth wire!
Appliances marked "double
insulated" do not have an
earth wire, because their
metal parts are covered
with insulating plastic, so it
won't give the user shocks.

10. No earth wire!
Appliances marked "double
insulated" do not have an
earth wire, because their
metal parts are covered
with insulating plastic, so it
won't give the user shocks.