Definitions
Electrical Equipment
: Any item used for such purposes as generation, conversion,
transmission, distribution or utilisation of electrical energy, such as machines
transformers. apparatus, measuring instruments, protective devices, equipment for
wiring systems and appliances.
Electrical Installation
: An assembly of associated electrical equipment, to fulfil a specific purpose or
purposes and havingco-ordinated characteristics.
Accessory
: A device, other than current-using equipment, associated with such equipment or
with the wiring of an installation.
Ambient Temperature:
The temperature of the air or other medium where the equipment is to be used.
Appliance
: Any device that utilises electricity for a particular purpose, excluding a luminaire or an
independent motor.
Insulation
: Non-conducting material enclosing, surrounding or supporting a live part.
Insulated conductor:
A conductor having only basic protection against shock, consisting of a covering of
insulation.
Cable:
An insulated conductor with an outer protective covering against external influences.
External Influences:
Any influence external to an installation which affects the design or
safety of the installation.
Fixed Wiring or Cable:
Wiring or cable mounted on a fixed support so that its position does not change.
Flexible Wiring or Cable:
Wiring or cable that may be moved in normal service between its points of
termination.
Conduit:
A system of tubing intended to enclose cable
s and wires in order to protect them from mechanical damage, and to allow them to be
drawn-in and withdrawn.
Cable Trunking System:
A factory-made system for enclosing cables and insulated wires,
normally of rectangular cross-section, one side of which can be removed, and
forming part of the wiring system.
Neutral Conductor
( symbol N ): A conductor connected to the neutral point of a system for the purpose of
transmitting electrical energy.
Phase Conductor
: A conductor of an AC system, other than a neutral conductor, intended for the
transmission of electrical energy( also called “line conductor” ).
Cable Coupler
: A means enabling the connection, at will, of two flexible cables. It consists of a
connector and a plug.
Enclosure:
A part providing an appropriate degree of protection of equipment against certain
external influences and, a defined degree of protection against direct contact with live
parts.
Building Void:
A space within the structure or components of a building, which may be
accessible at certain points.
This page summarised; Here’s a summary of the definitions:
This section defines key electrical terms. Electrical equipment includes any device involved in
generating or using electricity. An installation is a purposeful assembly of such equipment.
Accessories support the system without using current themselves. Terms like appliance,
insulation, and conductor types (insulated, fixed, flexible) clarify the roles and protection of
components. It also explains cable systems like conduits and trunking, and distinguishes
between neutral and phase conductors, as well as external influences and building voids
that affect design and safety,
Page 5
Common Electrical Conducting Materials
MATERIAL
Silver
PROPERTIES
Best conductor material.
Used to plate contacts to
Expensive
.
ensure
good electrical contact.
Soft and easily shaped.
Copper
Very good conductor.
Used extensively as a
Soft and easily drawn into wires.
conductor material in cables
Easy to joint and solder.
and busbars.
Good conductor of heat
Gold
Good conductor.
Used to plate contacts.
Does not corrode.
APPLICATIONS
Expensive.
Aluminium
Good conductor.
Used to manufacture
Low cost and weight.
larger cables and busbars.
Soft and easily shaped.
Overhead cables with steel core.
Not as flexible as copper.
Corrodes.
Tungsten
Easily drawn into very fine
wires. Lamp filaments.
Very high melting point.
Brass
An alloy of copper and zinc.
Used to manufacture cable
Easily machined.
glands, terminals, plug pins,
Resists
corrosion.
so
me conduit fittings, nuts,
bolts and washers.
Steel
Reasonably easy to shape.
Used to manufacture
conduit,
trunking,
enclosures and various fittings.
May be galvanised.
Tin
Resists corrosion.
Used to manufacture solder.
Coating on copper cables
insulated with vulcanised rubber.
Lead
Does not corrode.
Used to manufacture solder,
Easily shaped.
sheaths of cables, plates
in
lead-acid
tray,
cells.
Mercury
Liquid at normal temperatur
e.
Used in tilt switches.
Nichrome
Nichrome is an alloy of
Used to manufacture heating
nickel
and
elements.
Hard and resists corrosion
Carbon
Good conductor.
Brushes for electrical machines.
Hard wearing - self lubricating
- negative temperature co-efficient
of
resistance.
chromium
Page 5
Material
Properties
Applications
Silver
Best conductor, soft, expensive
Plating of contacts for excellent
conductivity
Copper
Very good conductor, easily shaped,
soldered, conducts heat well
Cables, busbars, general wiring
Gold
Good conductor, does not corrode,
expensive
Contact plating in
high-reliability devices
Aluminiu
m
Good conductor, light, low cost,
corrodes, less flexible than copper
Large cables, busbars, overhead
lines with steel core
Tungsten
High melting point, drawn into fine
wires
Lamp filaments
Brass
Copper-zinc alloy, corrosion-resistant,
easily machined
Cable glands, plug pins,
terminals, conduit fittings
Steel
Strong, shapeable, may be galvanised
Conduits, trunking, trays,
enclosures
Tin
Corrosion-resistant
Solder, cable coatings
(especially on rubber-insulated
cables)
Lead
Corrosion-resistant, easily shaped
Solder, cable sheaths, lead-acid
battery plates
Mercury
Liquid at room temperature
Tilt switches
Nichrome
Nickel-chromium alloy, hard,
corrosion-resistant
Heating elements
Carbon
Good conductor, hard, self-lubricating, Brushes in electrical machines
negative temp. coefficient of resistance
Page 5 summarised
Silver: Excellent conductor, used for plating contacts to ensure good electrical contact. Expensive and
soft.​
Copper: Very good conductor, commonly used in cables and busbars. Easy to shape and solder, also a
good conductor of heat.​
Gold: Good conductor, used for plating contacts, resistant to corrosion but expensive.​
Aluminium: Good conductor, low cost and weight, used in larger cables and busbars. Not as flexible as
copper and prone to corrosion.​
Tungsten: Drawn into fine wires, high melting point, used in lamp filaments.​
Brass: Copper-zinc alloy, corrosion-resistant, used in cable glands, terminals, plug pins, and various
fittings.​
Steel: Used for conduit, trunking, trays, and enclosures; can be galvanized for extra protection.​
Tin: Corrosion-resistant, used in solder and coating copper cables insulated with vulcanized rubber.​
Lead: Does not corrode, used in solder and cable sheaths for lead-acid cells.​
Mercury: Liquid at room temperature, used in tilt switches.​
Nichrome: Alloy of nickel and chromium, used for heating elements, resistant to corrosion.​
Carbon: Good conductor, used in brushes for electrical machines.
Page 6
Material
Propertie
s
PVC
(Polyvinyl
Chloride)
Weather-resistant, flexible, affected by
contact with creosote and certain insulating
materials, emits smoke and fumes when
burning
Cable insulation, cable
sheaths (standard grade 0 to
70°C, Arctic grade -20 to
+70°C)
Emits little smoke or fumes when
burning, flexible, resistant to high
temperatures
Cable insulation and sheath,
temperature range (-40 to
+90°C)
Flexible, ages over time, absorbs solvents and
swells, temperature range (-25 to +65°C),
high-temp type up to 85°C
Cable insulation, sheath,
moulded plug tops, extension
sockets
Crosslinked
Polyethylene
(XLPE)
Rubber
Silicone
Rubber
Application
s
Flexible, temperature range (-60 to
+260°C), can withstand up to 300°C
for short durations
Conductor insulation for
high-temperature areas, e.g., cooker
internal wiring, insulation sleeving
Plasti
c
Relatively cheap, not too brittle, can
be moulded into intricate shapes
Porcelain Hard, brittle, easily cleaned,
high-temperature range
Glas
s
Rigid, brittle, easily cleaned
Plugs, sockets, switches, fuse carriers, fuse
bases, conduits, trunking, and enclosures
Fuse carriers, bases, overhead line
insulators, high-temperature connectors
Overhead line
insulators
Glass
Fibre
Reasonably flexible,
high-temperature resistance
Asbesto
s
Reasonably flexible, high-temperature
resistance (old types)
Mica
Conductor insulation in high-temperature
areas (e.g., ovens), up to 170°C
Conductor insulation in
high-temperature areas
High-temperature range, brittle Toaster elements, motor commutator
insulation
Magnesium
Oxide
In powder form, high-temperature
range (145°C), hygroscopic (absorbs
moisture), good conductor of heat
Insulation in mineral insulated
sheathed cables (MIMS), sheathed
elements for kettles, cookers,
immersion heaters
Page 6 summary
Material
Properties
Applications
PVC
Weather-resistant, flexible, affected by some
chemicals
Used in cable insulation
and sheaths
Crosslinke
d
Polyethyle
ne (XLPE)
Flexible, high-temperature resistant
Used for cable insulation
and sheaths
Rubber
Flexible, ages over time, absorbs solvents
Used in cable insulation,
plug tops, and extension
sockets
Silicone
Rubber
Flexible with high-temperature resistance
Ideal for conductor
insulation in high-temp
areas like cookers
Plastic
Cheap, mouldable, and durable
Used in plugs, sockets,
switches, fuse carriers,
and enclosures
Porcelain
Hard and brittle
Used for fuse carriers,
bases, and high-temp
connectors and
insulators
Glass
Rigid, brittle
Used primarily in
overhead line insulators
Glass
Fibre
Flexible, high-temperature resistant
Used for conductor
insulation in
high-temperature areas
(e.g., ovens)
Asbestos
Flexible and heat-resistant, used in older high-temp
conductor insulation
Used in older
high-temperature
conductor insulation
Mica
Brittle but high-temperature resistant
Used in toaster elements
and motor insulation
Magnesiu
m Oxide
High-temperature resistant, hygroscopic
Used in mineral insulated
cables and heating
elements
Butyl
Rubber
Tough and flexible, remains flexible in harsh
conditions (-40°C to +85°C)
Used in extension leads
for harsh conditions
Page 7
1.Conductor
2.Insulation
3.Sheath ( Mechanical Protection )
The most common conductor material used is copper. Aluminium is used for larger
cables and its use is not permitted in domestic installations.The most common insulation
used is PVC. Other materials are used as insulation depending on what the cable is being
used for and where it is being installed.The most common mechanical protection used
is PVC. Further protection is provided by installing cables in locations where they are
unlikely to be damaged. Where this is not possible,cables must be installed in conduit,
trunking or ducting. Otherwise a suitably armoured cable must be used. When
cables are installed in conduit or trunking they need not have any other form of
mechanical protection. The conduit or trunking is deemed to be its mechanical
protection.Cables are manufactured in a range of common sizes. These are decided by the
Cross
Sectional
Area ( CSA ) of the conductor, which is specified in square milli-metres ( mm
2
).
The following is a list of the standard
sizes used in domestic installati