-(ac) This means the voltage supplied is constantly changing
Amperes - Is the unit of current usually abbreviated
|Back Box- this is the
unit to which the faceplate attaches
| Cable - Group of two
or more insulated wires.
Cable - Coupler/Connector Item designed for
connecting or disconnecting two flexible cables one cable has
a male fixed to its end connector
the other a female
Cable Clips -A means of fixing a cable or
cables to a surface
Cable Core - A cable core is the portion of an insulated cable
that conducts the electricity lying under the protective covering
Catenary wire -Supports the weight of the
external cable when linking power from one building to another
House to shed
Circuit - Interconnection of components to
provide an electrical path between two or more components supplied
from the same
source and with the same overcurrent protection device/s.
Circuit breaker - Is a form of fuse that can
be reused. It is designed to break the electrical circuit if
there is a chance
of it overloading. Stops the flow of current in a predetermined
time by means of a coil inside the circuit breaker this creates
an electromagnet. The more the current flows, the stronger
the electromagnet becomes. If the current gets above the predetermined
level , the electromagnetism becomes powerful enough to pull
a switch and break the circuit.
Contact - Current carrying part of a switch,
relay or connector.
Continuity - Occurs when a complete path for
Continuity - Test A test to verify the continuity
of a circuit
Conduit - A protective metal or plastic tube
that wires run through.
Compact Fluorescent Lamp- Generally the term
applied to smaller diameter fluorescent lamps
Consumer Unit - The hub of a homes electrical
system normally where the fuses are installed
Current - Measured in amperes, it is the
flow of electrons through a conductor. Also know as electron
Circuit Tester - A meter designed to measure
several properties of electricity all in one box. Some circuit
current, voltage and resistance others will also test operating
times of RCDs(see also Meter, Ammeter, Voltmeter, Ohmmeter)
| Dimmer switch - A switch
with a component inside called a variable resistor. As the
knob on the dimmer
is turned, so the amount of resistance in the circuit gets
greater and this makes the current flowing less. With less
current a bulb shines more dimly. It will only work with filament
DC Power Supply - Any source of DC power
for electrical equipment often used on portable equipment e.g.
Dedicated Radial Circuit - A circuit run directly
from the consumer unit (these are mainly used when Installing
|Earthing Systems - The
main earthing used in the UK as defined by BS 7671 regulations
312-03 are as follows
TN-S , TN-C-S , TT and IT.
| Fluorescent light -
It does not have a filament that glows, but is contains (mercury)
vapor that gives
off an invisible kind of light called ultra violet light. The
ultra violent light strikes particles of a coating on the tube,
which then give out visible light (they fluoresce).Very little
heat is given out,and more of the power is turned into light
this makes a fluorescent tube more efficient and cheaper to
operate than a filament light bulb.
Fluorescent tubes can now be made very compact. They are called
'energy saving' lights
Faceplate - The outer part of a socket or
Fiber optics Laser's - Light output carries
information that is conveyed between two points by thin glass
these will in the future be used more in domestic situations
Filament Light bulb - Is glass bulb containing
a thin metal wire called a filament that heats up when electricity
Fixture - Any permanently connected light
or other electrical device that consumes power.
Fuse - A protective device in the current
path that melts or breaks when current exceeds a predetermined
a given time.
Fuse Wire/Element -The part of the fuse designed
Fuse Holder - Part of the fuse that holds
the fuse wire/element
Fuse Board - Place were fuses are located.
| Grommet - A washer normally
rubber designed to prevent cable coming into contact with metal
back box on
a switch or socket
|HERTZ (Hz.) Unit of frequency. One hertz
is equal to one cycle per second
| Infrared - Electromagnetic
heat radiation whose frequencies are above the microwave frequency
below red in the visible band ,often used on TV remotes and
on alarm sensors
Insulated - When a non conducting material
is used to isolate conducting materials from one another.
Insulating material - Material that will prevent
the flow of current due to its design and chemical composition
| Junction - Contact or
connection between two or more wires or cables.
Junction Box- Place where connection between
two or more wires cables are housed
|Kilowatt-hour meter -
A meter used by electric companies to measure the amount of
power used in your
|Load Current - Current
drawn from a source by a load.
Lamp - Device that produces light.
Light filament/bulb - Thin thread of carbon
or tungsten which produces heat or light with the passage of
Live - Term used to describe a circuit or
piece of equipment that is on and has current flow within it.
|Magnetic circuit breaker -
Circuit breaker that is tripped or activated by use of an electromagnet.
Megger - A test instrument for measuring the insulation resistance
of conductors and other electrical equipment; specifically,
a megaohm (million ohms) meter; this is a registered trade
mark of the James Biddle Co.
Meter - Any electrical or electronic measuring
|Overcurrent - Any current in excess of
the rated current of equipment or the ampacity of a conductor.
It may result from overload, short circuit or ground fault.
Overload - Condition that occurs when the
load is greater than the system was designed to handle .Can
Overload protection - Protective device such
as a fuse or circuit breaker that automatically disconnects
a load when current
exceeds a predetermined value for a given time.
|Power Supply - Electrical
equipment used to deliver either AC or DC voltage
| Residual Current Device (rcd) A
mechanical device intended to open the contacts when the residual
reaches a pre determined level for a specific time
|Short circuit Low resistance connection
between two points in a circuit typically causing excessive
current and tripping of overcurrent protection devices
Switch, general use - A switch intended for use in general
distribution and branch circuits.It is rated in amperes and
is capable of interrupting its rated voltage
Switch - A device for connecting and disconnecting
power to a circuit.
Step-down transformer Transformer in which the output AC voltage
is less than the input AC voltage.(Often used with lighting)
Step-up transformer -Transformer in which
the output AC voltage is greater than the input AC voltage.
Supply Voltage - Voltage provided by a power
|Test Sequence of operations intended to
verify the correct operation or malfunctioning of a piece of
equipment or system.
Transformer - Inductor with two or more windings.
Through mutual inductance, current in one winding called a
primary will induce
current into the other windings called secondaries.
Troubleshooting - Systematic approach to locating
the cause of a fault in an electronic circuit or system
|Volt - Unit of potential
difference or electromotive force. One volt is the potential
difference needed to produce
one ampere of current through a resistance of one ohm.
Voltage(V) - Term used to designate electrical
pressure or force that causes current to flow.
Voltage Drop - Voltage or difference in potential
developed across a component due to current flow
|Watt - Unit of electrical
power required to do work at the rate of one joule per second.
One watt of
power is expended when one ampere of direct current flows through
a resistance of one ohm. In an AC circuit, true power is the
product of effective volts and effective amperes, multiplied
by the power factor