Distribution Boards. It includes Supply, Installation, Testing and Commissioning of Distribution Boards standard company fabricated or to be fabricated by fabricator & should be double door type. Distribution Board shall be double door type with extended loose wire box at the top & suitable for flush installation. All distribution boards shall be of three phase (415 Volts) type with incoming isolator or MCB &/or ELCB as in Chapter of quantities. Distribution boards shall contain plug in or bolted type miniature circuit breaker mounted on bus bars. Miniature circuit breakers shall be quick made & quick break type with trip free mechanism. MCB shall have thermal & magnetic short circuit protection. MCB shall conform to IS 8828-1978. Distribution boards shall comprise of 200A rating copper bus bar, earth terminal, MCB, DP, RCCB and neutral link mounted in three-tier phase wise. All distribution boxed shall be made by approved/licenses MCB/DP manufacturer. The bus bar shall be such that circuit could be isolated easily. Neutral bus bars shall be provided with the same number of terminals, as there are single ways on the board, in addition to the terminals for incoming mains. An earth bar of similar size at the neutral bar shall also be provided. Phase barrier shall be fitted and all live parts shall be screened from the front. Ample clearance shall be provided between all live metal and the earth case & adequate space for all incoming & outgoing cables. All distribution boards enclosures shall have an etched zinc base stove painted followed by synthetic stoved enamel, colour light gray. A circuit identification card in clear plastic cover shall be provided for each distribution board and made from 16-gauge sheet. Earth leakage circuit breaker/residual current circuit breakers-Earth leakage circuit breaker shall be current operated type and of 100 ma sensitivity unless otherwise stated. For single-phase distribution, ELCB shall be housed within the DB box. For three-phase distribution board, the ELCB shall be housed in the same box.
Distribution Boards. 1.0 SPECIFICATIONS Distribution boards shall be fabricated from 18-gauge M.S. sheet or shall be readymade as specified in the make of material list. It shall be of double door type with hinged (lockable if required) door suitable for recessed mounting in wall. Distribution boards shall be powder coated with 7-tank process application. The distribution boards shall be provided with phase barriers, wiring channels to accommodate wires and individual per phase neutral links. There shall be separate or individual earth link as per requirement. Proper arrangement shall be made for mounting of MCB’s and other accessories. Distribution boards shall meet with the requirements of IS 2675 and marking arrangement of bus bars shall be in accordance with I.S. standards. Bus bars shall be suitable for the incoming switch rating and sized for a temperature rise of 35° C over the ambient. Each board shall have two separate earthing terminals. Circuit diagram indicating the load distribution shall be pasted on the inside of the DB as instructed. One earthing terminal for single phase and two terminals for 3 phase DB's shall be provided with an earth strip connecting the studs and the outgoing ECU earth bar. The top and the bottom faces of the D.B. shall be provided for conduit entry of minimum 1” dia. The faces if asked shall be kept detachable. All outgoing feeders shall terminate on a terminal strip which in turn is interconnected to the MCB/Fuse base by means of insulated single conductor copper wires as follows Up to 15 A 2.5 xx.xx. 40 A 10 xx.xx. 25 A 4.0 xx.xx. 63 A 16 xx.xx.
Distribution Boards. The distribution boards and all component parts shall be manufactured and tested in accordance with IEC 60439 and be capable of withstanding without injury the mechanical and electrical stresses set up by any fault current for twice the period required to disconnect such fault on any circuit. Each distribution board shall have a dustproof metal case of sheet steel with an enamelled finish and shall have hinged doors fully gasketed with push-button handle incorporating a cylinder type lock. The colour of the enamel finish shall match the colour of other switchgear in the same room. The metal casing shall be provided with a gland plate for cable entry corresponding to the circuit capacity of the distribution board and a suitable screened brass earthing stud. Distribution boards for exterior use shall have a corrosion resistant finish and be weatherproof to IPW 55 minimum. Each current carrying component shall be so designed that under continuous rated full load conditions in the climatic conditions at Site the maximum total temperatures permitted under the relevant Standards are not exceeded. All distribution boards shall incorporate a disconnector which shall disconnect the incoming supply to the distribution board. This disconnector shall take the form of an on-load switch. Disconnectors up to and including 100 A shall be of the moulded pattern and mounted internally unless otherwise specified. All distribution boards require residual current protection on the incoming supply. The tripping sensitivity shall normally be 300 mA for lighting distribution boards and 30 mA for socket outlets or air conditioning distribution boards. Where a distribution board feeds critical equipment, individual residual current protection shall be used to avoid loss of all power supplies. The cables feeding the distribution boards shall be connected directly to the incoming disconnector or neutral bar as appropriate. All distribution boards shall be equipped with overvoltage protection devices which are designed according an lightning protection zone concept accomplice the IEC 81/216/CDV:2003. Neutral bars shall have an appropriate number of ways relative to the size of the board. The metal surface adjacent to any live part and all spaces between phases shall be protected by barriers or fireproof insulation material.
Distribution Boards a) CRITICAL Board - DB1 The critical power distribution board comprises an input mccb, isolation transformer, distribution board and CLEAN earth terminal bar. The rating of the P.D.U is to be 200kVA, with a TP & N distribution pan assembly to accommodate 63 amp triple and single phase mcb's. The P.D.U. is to be connected to the FIRE ALARM SYSTEM and will automatically switch off, on receipt of a second stage fire alarm, within the communications room. The P.D.U. is also connected an EMERGENCY POWER OFF system within the communications room and will automatically switch off, when the E.P.O. glass break unit is operated manually.
Distribution Boards
