Basic Electrical Installation Work
100
Properties conductors and insulators
In Fig.
It good insulator, but degrades and becomes brittle when exposed to
sunlight. Let now define the terms and properties some the materials used
in the electrotechnical industry.
Rubber tough elastic substance made from the sap tropical plants. Most corrosion
takes place when metal contact with moisture (see also mild steel
and zinc).
Definition
Polyvinylchloride (PVC) used for cable
insulation thermoplastic polymer.
They are good insulators, but give off toxic fumes when burned. Plug tops, socket outlets and
switch plates are made from this material.
Definition
Ferrous word used describe all
metals which the main constituent
is iron.
Definition
Alloy alloy mixture two or
more metals. The word ‘ferrous’ comes from the Latin word ferrum meaning iron. These electrons can easily become
‘free electrons’ which allows heat and electricity pass easily through the
material.
All materials are made atoms and electrons.
Non-ferrous Metals which not contain iron are called non-ferrous.
Corrosion The destruction metal chemical action.
Definition
Corrosion The destruction metal
by chemical action.
Thermoplastic polymers These may repeatedly warmed and cooled
without appreciable changes occurring the properties the material. They
are non-magnetic and resist rusting.
Definition
Non-ferrous Metals which not con-
tain iron are called non-ferrous. What makes them differ-
ent materials the way which the atoms and electrons are arranged and
how strongly the electrons are attracted the atoms. They have
a flexible quality when operated maximum temperature 70°C but
should not flexed when the air temperature near 0°C, otherwise they
may crack. Synthetic artificial rubber carefully manufactured have all the
. Copper, aluminium, tin, lead, zinc
and brass are examples non-ferrous metals.
Definition
A conductor material, usually a
metal, which the electrons are
loosely bound the central nucleus.
These electrons can easily become
‘free electrons’ which allows heat and
electricity pass easily through the
material.
An insulator material, usually non-metal, which the electrons are
very firmly bound the nucleus and, therefore, will not allow heat elec-
tricity pass through it. Cast iron, wrought iron and steel
are all ferrous metals. 4.
A conductor material, usually metal, which the electrons are
loosely bound the central nucleus. Alloy alloy mixture two more metals.
Ferrous metals have magnetic properties.
Thermosetting polymers Once heated and formed, products made from
thermosetting polymers are fixed rigidly.1 the last chapter looked the atomic structure materials.
Definition
An insulator material, usually a
non metal, which the electrons are
very firmly bound the nucleus and,
therefore, will not allow heat elec-
tricity pass through it.
Synthetic rubber manufactured, opposed being produced natu-
rally.
Ferrous word used describe all metals which the main constituent
is iron. Brass alloy cop-
per and zinc, usually the ratio 70–30% 60–40%. Polyvinylchloride (PVC) used for cable insulation thermo-
plastic polymer.
Definition
Thermoplastic polymers These may be
repeatedly warmed and cooled with-
out appreciable changes occurring in
the properties the material
