Terminology and Definitions: Electrical and Electronic Engineering Installations

CELING ROSE: A ceiling rose is used for terminating the point wiring for a Light or a Fan in the ceiling. It has brass terminals in which incoming cables are terminated using brass screws on the terminals and the outgoing flexible cables get connection through the screw connections.

CIRCUIT: An assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective device.

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

CIRCUIT BREAKER: A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent, without injury to itself when properly applied within its rating.

CIRCUIT BREAKER: A device used to break a circuit during over current or short circuit condition. An LV Circuit Breaker is used in a low voltage distribution system and an HV Circuit Breaker is used in a high voltage distribution system.

CORD, FLEXIBLE CABLE: A flexible cable having large number of strands of conductors of small crosssectional area with a soft PVC insulation. Two flexible cords twisted together may be termed as twin flexible cord. However, some flexible cords are made following thestyle of a twin core PVC insulated copper cables but much soft and flexible.

CUTOUT: Any appliance for automatically interrupting the transmission of energy through a conductor when the current rises above some predetermined value. A cutout contains a part for holding either fuse wire (rectangular cross section type) or a part for holding tubular fuse (cylindrical body rectangular cross section type). (see Fuse)

DB: Distribution Board. This may be the box where the main incoming cable enters and terminates from the main service feed connection. The SDBs get feed from a DB.

DEMAND FACTOR : The ratio of the maximum demand of a system, or part of a system, to the total connected load of the system or the part of the system under consideration.

DUCT : A closed passageway formed underground or in a structure and intended to receive one or more cables which may be drawn in.

EARTH : The conductive mass of the earth, whose electric potential at any point is conventionally taken as zero.

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

EARTH LEAD WIRE: The final conductor by which the connection to the earth electrode is made.

EARTH CONTINUITY CONDUCTOR (ECC): 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. It may be in whole or in part the metal conduit or the metal sheath or armour of the cables, or the special continuity conductor of a cable or flexible cord incorporating such a conductor. ECCs of appropriate size must run from an MDB to its DBs, from a DB to its corresponding SDBs, from an SDB to the Switch Boards under this SDB, from an SDB to the BDBs if there are any, from a BDB to the Switch Boards under this BDB, from an SDB or a BDB to the Sockets under this SDB or BDB.

EDB: Emergency Distribution Board. This may be the box where the main incoming cable from the Emergency or Standby Generator Panel enters and. The ESDBs get feed from a EDB.

EFDB: Emergency Floor Distribution Board located in each of the floors of a multistoried building. The EDBs get feed from EFDB.

ENGINEERINCHARGE: An engineer responsible for implementation /execution of the work of a building or a project.
Such an engineer is expected to have significant knowledge in Electrical Engineering, Electrical Construction, Measurement, Codes and Practices of such work and availability of different materials needed for the construction.

FDB: Floor Distribution Board located in each of the floors of a multistoried building. The DBs get feed from FDB.

FUSE : A device that, by the fusion of one or more of its specially designed and proportioned components, opens the circuit in which it is inserted when the current through it exceeds a given value for a sufficient time. Fuse is generally made of fusible wires of appropriate ratings which is either mounted inside glass tubes or porcelain tubes or on a two terminal cutout.

FUSE SWITCH: A composite unit, comprising a switch with the fuse contained in, or mounted on, the moving member of the switch.

LIGHTING FITTING: 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, or a portable unit.

INSULATION : Suitable nonconducting material, enclosing, surrounding or supporting a conductor. Usually PVC, polymer, specially treated rubber.

LIVE : Electrically charged so as to have a potential different from that of earth. Also known as ALIVE.

LUMINAIRE: A complete light fitting consisting of lamp, holder, starting gears, reflectors, housing and mounting accessories.

LT / LV and HT/ HV: LT or LV in this document indicates 230 Volt single phase and 400 volt 3 phase. HT or HV in this document indicates 11KV Line to line 3 phase system.

MDB: Main Distribution Board. This is the distribution box where the main incoming cable enters and terminates from the main service feed connection of a large building. The FDBs get feed from MDB.

OVERCURRENT : A current exceeding the rated current. For conductors, the rated value is the nominal current carrying capacity.

PANEL BOARD : A single panel or a group of panel units designed for assembly in the form of a single panel including buses, automatic overcurrent devices, and with or without switches for the control of light, heat, or power circuits, designed to be placed in a cabinet or cutout box placed in or against a wall or partition and accessible only from the front.

PLUG : A device carrying metallic contacts in the form of pins, intended for engagement with corresponding socket contacts and arranged for attachment to a flexible cord or cable. A plug may contain tubular fuse inside it although some plugs do not contain fuse.

POINT (in wiring) : A termination of the fixed wiring intended for the connection of current using equipment e.g., a Light, a fan, an exhaust fan.

SDB: Sub Distribution Board located in the same floor of a building and connected to the DB. The BDBs get feed from SDB.

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

SWITCH : A manually operated device for closing and opening or for changing the connection of a circuit. A 5A SPST switch is used for the control of a Light or Fan point. A 5A SPDT switch is also used for the control of a Light or Fan point.

SWITCHBOARD : An assemblage of switchgear with or without instruments the term, however, does not apply to a group of local switches on a final subcircuit where each switch has its own insulating base.

SWITCHGEAR : Main switches, cutouts or fuses, conductors and other apparatus in connection therewith, used for the purpose of controlling or protecting electrical circuits or machines or other current using appliances.

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