Mains Electricity - Insulation.
Insulation means putting something
which does not conduct electricity (an insulator)
between a live conductor and yourself.
Any metal is a conductor of electricity.
Any non-metal is an insulator,
with the exception of graphite which conducts electricity
because of its unusual molecular structure.
If you do not know what is a metal and what is a non-metal,
see the GCSE Chemistry site at the periodic table.
The wires which we use to conduct electricity are made
of a high purity copper metal, which is an excellent conductor.
The insulator which covers the wires is a polymer
(often just called "plastic"). It is an excellent insulator,
flexible enough to bend around corners and cheap to make.
Older wires had a rubber material as their insulation
but the rubber cracked and split as it got older and so
it has been replaced in houses by new PVC covered cable.
This is an example of a new material replacing an older one
because the new material has superior properties.
Insulation can become unsafe if it is damaged
or if it is wet because impure water will conduct electricity.
Some appliances are double insulated.
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