Transcript Wiring a Plug

Wiring a Plug
Earth
wire
Neutral
wire
Outer
insulation
Wire
Live
Neutral
Earth
Live wire
Fuse
Cable
grip
Colour of Insulation
The Earth Wire
The Earth Wire is a safety device.
No current flows through it when in normal operation.
The Earth Wire is connected to the casing of the appliance.
If the Live wire touches the casing then
 the Earth wire provides an easy path
( missing out the inside parts of the appliance )
 a large current tries to flow
 the fuse melts
 the appliance is safe
Double Insulation

Some appliances don’t need an Earth Wire.

Their casing is made of plastic.

These appliances only require a 2-core flex ( Live and Neutral ).

Such appliances have the symbol:
Double Insulation Symbol
The Live & Neutral Wires
switch
fuse
Live
(to high voltage)
neutral



The live wire is connected to the high voltage.
The switch and the fuse are used to disconnect the appliance from
the high voltage when it’s not in use or if a fault occurs.
Therefore both the switch and the fuse must be connected in the
live wire (brown) between the high voltage and the appliance.
If the neutral and live are mistakenly swapped over, then the appliance
is still connected to the high voltage when it is switched off.
switch
fuse
neutral
Live
(to high voltage)
Although there is no current flow when the appliance is switched off,
the casing of the kettle is live.
Even if the fuse were to blow the case remains live as the high voltage
is connected directly to the casing.