Accessory:

Any device, associated with the wiring and electrical appliance of an installation, for example, a switch, a fuse, a plug, a socket-outlet, a lamp holder, or a ceiling rose.

Aerial Conductor:

Any conductor, which is supported by insulators above the ground and is directly exposed to the weather.

NOTE - Four classes of aerial conductors are recognized:

a) Bare aerial conductors,

b) Covered aerial conductors,

c) Insulated aerial conductors, and) Weatherproof neutral-screened cable.

A mechanical switching device capable of making, carrying and breaking currents under normal circuit conditions and also making, carrying for a specified time and breaking currents under specified abnormal circuit conditions such as those of a short-circuit.

An outgoing circuit connected to one-way distribution fuse-board and intended to supply electrical energy at one or more points to current-using appliances, without the intervention of a further distribution fuse board other than a one-way board. It includes all branches and extensions derived from that particular way in the board.

An insulated incombustible support normally used for insulated.

A substance or body which allows current of electricity to pass continuously.

A combination of a plug and socket arranged for attachment to a portable electrical appliance or to a flexible cord.

A conductor not covered with insulating material.

A conductor with no provision for its insulation from earth.

A conductor adequately covered with insulating material of such quality and thickness as to prevent danger.

A box forming a part of wiring installation provided to contain joints in the conductors of cables of the installation.

The ends of the electrical conductors situated upon any consumer’s premises and belonging to him at which the supply of energy is delivered from the service line.

A flexible cable having conductor of small cross-sectional area. Two flexible cords twisted together are known as ‘Twin Flexible Cord’

The elementary quantity of electricity flowing through a given section of a conductor divided by the corresponding indefinitely small time.

Equipment intended to convert electrical energy into another form of energy, for example, light, heat or motive power.

Any appliance for automatically interrupting the transmission of energy through any conductor when the current rises above a predetermined amount, for example, fusible cut-out.

At or about earth potential and/or disconnected from any live system.

A material medium in which an electric field can exist in a stationary state.

A system of earthing in which the parts of an installation are so earthed as specified but are not connected within the installation to the neutral conductor of the supply system or to earth through the trip coil of an earth leakage circuit-breaker.

A device used to open (or close) a circuit when either negligible current is interrupted (or established) or when the significant change in the voltage across the terminals of each of the pole of the disconnector occurs; in the open position it provides an isolating distance between the terminals of each pole.

An assemblage of parts including one or more fuses arranged for the distribution of electrical energy to final sub-circuits.

A totally enclosed structure, ‘cubicle containing bus-bars connected to incoming and outgoing distribution feeders controlled through links/fuses.

Drop-out current is the maximum coil current below which an energized relay will return to its "normal" state.

A non-interchangeable fuse comprising a fuse-base a screw type fuse- carrier, a gauge piece and a fuse-link.

A connection to the general mass of earth by means of an earth electrode. An object is said to be ‘earthed’ when it is electrically connected to an earth electrode; and a conductor is said to be ‘solidly earthed’ when it is electrically connected to earth electrode without a fuse, switch, circuit-breaker, resistance or impedance in the earth connection.

The conductor including any clamp, connecting to the earthing lead or to each other those parts of an installation which are required to be earthed.

A metal plate, pipe or other conductor electrically connected to the general mass of the earth.

Accidental connection of a conductor to earth. When the impedance is negligible, the connection is called a dead earth.

The current flowing to earth on account of imperfect insulation.

The final conductor by which the connection to the earth electrode is made.

An arrangement of bodies or media through which a current can flow.

The movement’ of electricity in a medium or along a circuit. The direction of the current is accepted as opposite to that of the motion of negative electricity.

A machine for converting electrical energy into mechanical energy.

The electrical machines, apparatus and circuits forming part of an electrical installation or a power system.

A conducting element used for conveying current to and from a medium.

An enclosure containing bus-bars, with fuses, for the purposes of protecting, controlling or connecting more than one outgoing circuit fed from one or more incoming circuits.

A device for supporting or containing a lamp or lamps (for example, fluorescent or incandescent) together with any holder, shade, or reflector, for example, a bracket, a pendant with ceiling rose, an electrolier, or a portable unit.

Equipment fastened to a support or otherwise secured in a specific location.

A material capable of being easily ignited.

The passage of a disruptive discharge round an insulating material.

A switching device that by the melting of one or more of its specially designed and proportioned components, opens a circuit in which it is inserted and’ breaks the current when this exceeds a given value for a sufficient time.

The fixed part of a fuse provided with terminals for connection to the system. The fuse-base comprises all the parts necessary for insulation.

The movable part of a fuse designed to carry a fuse-link. The fuse-carrier does not include any fuse-link.

That part of a rewirable fuse, which is designed to melt and thus open the circuit.

The part of the fuse including the fuse-element which requires replacement by a new fuse-link after the fuse has operated and before the fuse can be put back to service.

A switch in which a fuselink or a fuse-carrier with fuse-link forms the moving contact of the switch.

A machine for converting mechanical energy into electrical energy.

Portable equipment intended to be held in the hand during normal use, in which the motor, if any, forms an integral part of the equipment.

An alternating current motor without a commutator in which one part only, the rotor or a stator, is connected to the supply network, the other working by induction.

A conductor is said to have double insulation when insulating material intervenes not only between the conductor and its surrounding envelope (if a cable) or immediate suport (if bare), but also between the envelope or support and earth.

An appliance having accessible metal part is doubly insulated when protective insulation is provided in addition to the normal functional insulation, in order to protect against electric shock in case of breakdown of the functional insulation.

An abnormal decrease in insulation resistance.

A conductor other than cable, used for external connection between terminals of equipment.

A device designed to protect electrical apparatus from high transient voltage and to limit the duration and frequently the amplitude of follow current. The term ‘lightning arrester’ includes any external series gap which is essential for the proper functioning of the device as installed for service, regardless of whether or not it is supplied as an integral part of the device.

charged so as to have a potential difference from that of earth.

A compact mechanical device for making and breaking a circuit both in normal conditions and in abnormal conditions, such as those of overcurrent and short-circuit.

A machine, which consists of an electric motor mechanically, coupled to a generator.

A system of earthing in which the parts of an installation, specified, to be earthed are connected to the general mass of earth and, in addition, are connected within the installation to the neutral conductor of the supply system.

Includes the neutral conductor of a three-phase four-wire system, the conductor of, a single-phase or dc installation which is earthed by the supply undertaking (or otherwise at the source of the supply), and the middle wire or common return conductor of a three-wire dc or single-phase ac system.

are those suitable for installation in open air.

Operating conditions in an electrically undamaged circuit, which causes an over current.

Electric or magnetic circuits are said to be in parallel (or shunt) when current or flux is divided between them.

A point shall consist of the branch wiring from the branch distribution board, together with a switch as required, as far as and including the ceiling rose or socket outlet or suitable termination. A three-pin socket-outlet point shall include in addition, the connecting wire or cable from the earth pm to the earth stud of the branch distribution board.

Equipment which is moved while in operation or which can easily be moved from one place to another while connected to the supply.

Pull-in current is the minimum amount of coil current needed to actuate a solenoid or relay from its "normal" (de-energized) position.

A device designed to produce sudden predetermined changes in one or more physical systems on the appearance of certain conditions in the physical system controlling it.

An arrangement of elements so that they all carry the same current or flux.

An arrangement of elements of which some are connected in series and others in parallel.

The conductors and equipment required for delivering energy from the electric supply system to the wiring system of the premises served.

The intentional or accidental connection of two points of a circuit through negligible impedance. The term is often applied to the group of phenomena, which accompany a short circuit between points at different potentials.

A solenoid is a device that produces mechanical motion from the energization of an electromagnet coil. The movable portion of a solenoid is called an armature.

A brilliantly luminous phenomenon of short duration which characterizes a disruptive discharge.

Either fixed equipment or equipment not provided with a carrying handle and having such a mass that it cannot easily be moved.

A mechanical switching device capable of making, carrying and breaking currents under normal circuit conditions which may include specified operating overload conditions and also carrying for a specified time currents under specified abnormal circuit conditions such as those of a short-circuit.

An assemblage of switchgear with or without instruments but the term does not apply to a group of local switches or a final sub-circuit where each switch has its own insulating base.

A switch in which one or more poles have a fuse in series in a composite unit.

A general term covering switching devices and their combination with associated control, measuring, protective and regulating equipment, also assemblies of such devices and equipment with associated inter-connections, accessories, enclosures and supporting structures intended in principle for use in connection with generation, transmission, distribution and conversion of electric energy. Control gears are switching devices intended in principle for the control of electrical energy consuming equipment.

A piece of apparatus, without continuously moving parts, which by electromagnetic induction transforms variable voltage and current in one or more other windings usually at different values of voltage and current and at the same frequency.

The voltage which normally exceeds 650 volts (but less than 33 kV).

The voltage exceeding 33 kV under normal conditions.

The voltage which does not normally exceed 250 volts.

The voltage which normally exceeds 250 volts but does not exceed 650 volts.

The line of integral from one point to another of an electric field taken along a given path.