The electrical DB (distribution boards) for high-rise office installations shall be non-ventilated, naturally cooled, metal enclosed type, flush fronted and suitable for front access and shall be built to comply with IEC 60439-1. All louvers shall be covered with wire mesh.
The distribution boards shall contain MCCB (moulded case circuit breakers), MCB (miniature circuit breakers), RCD (residual current devices) and busbars as indicated in the contract documents. The DB shall be suitable for wall mounting or floor mounting as appropriate.
All necessary fixing materials, mounting bolts, etc shall be provided for the type of mounting mentioned.
All operating devices shall be mounted for installation, cable termination and maintenance operation at the front of the panel.
All distribution panel located outside the riser and public area shall have key lock handle.
Enclosure and Degree of protection
The DB enclosures shall be fabricated from rolled steel angle sections and shall be self supporting when assembled, uniform in height and depth from front to back. Sheet steel used shall not be less than 2 mm thick, anti-rust coated steel plate.
The distribution board shall be rigidly constructed to be stand alone units without any possibility of sagging, deformation or warping.
The front covers of the DB shall be of hinged-door type. The front doors shall be provided with lockable push button type. The doors shall be arranged to seal onto the board frame by means of a non-perishable dust-proof material. The sealing material shall be synthetic rubber and not foam. Doors shall be effectively earthed to the fixed enclosure by braided straps. Cover bolts or nuts shall be retained in place when undone.
For all internal DB installation, the degree of protection for the DB enclosures as per IEC 60529 shall be at least IP 41. When the doors are opened, the degree of protection to all live parts shall be at least IP 20.
All the distribution panels shall have Form 1 construction in compliance with IEC 60439-1.
The incoming and outgoing cable entry on the distribution boards shall be protected with rubber material to prevent damage to the cables.
Selection of components
All components shall be standardized as far as practical and shall comply with relevant IEC publications.
Busbars
Busbars for the DB shall be of plain hard-drawn, high-conductivity, electrolytic copper bars in accordance with BS EN 13601: 2002 and of adequate rectangular cross-section to carry continuously the specified current without overheating and shall be rigidly mounted on insulators so as to withstand any mechanical force to which they may be subjected under maximum fault condition.
The DB busbars shall be colored red, yellow, blue and black at appropriate points to distinguish the phases and neutral. No tapes shall be used.
Moulded case circuit breakers (MCCB)
Refer to the MCCB section for the details on MCCBs.
Type test certificates shall be produced for the MCCB selected from internationally recognized testing laboratories.
Miniature circuit breakers (MCB)
Refer to MCB section or details on MCBs.
Wiring
Refer to Electrical DB Wiring section for details on the DB wiring.
Residual current devices
Residual current devices shall provided as indicated in the design drawings and construction drawings.
Refer to Protection, Metering and Control section for details.
Type test certificates shall be produced for the RCCB/ ELCB selected from an independent internationally recognized independent testing laboratories.
Finishing and painting
Refer Electrical DB paintwork section for details on finishing and painting of electrical DB.
Copyright http://electricalinstallationblog.blogspot.com/ Electrical DB installation
Showing posts with label DB. Show all posts
Showing posts with label DB. Show all posts
Thursday, December 17, 2009
Electrical DB wiring
Following is a sample specifications for the wiring of an electrical DB. Refer the section on Electrical DB installation for specification details on the construction of distribution boards.
Photo 1 - Internal wiring of an electrical DB
Terminals for external conductors All conductor terminals shall be suitable for copper conductors.
All cable termination assemblies shall have facilities for entry of cables from both the top and the bottom of the distribution boards. Cable entries, cable clamping, earthing facilities and supporting devices that are provided shall be suitable for the type, size and number of the incoming cables.
The identification ferrules Both ends of each wiring conductor shall be provided with identification ferrules. The ferrules shall be made of an insulating material of a type not affected by oil or damp. The characters shall be suitably marked in black. (See photo here: Wiring identification ferrules)
The ferrules shall be of the continuous ring type. A slide-on type will not be acceptable. The markings shall be in accordance with the relevant manufacturer’s drawings.
The wiring cables The minimum allowable cross-sectional area of control cables shall be 1.0 mm.sq. Wiring cables with a cross-sectional area of 1.5 mm.sq or larger shall always be stranded. The secondary circuits of current transformers with a 5 A rating shall not be less than 2.5 mm.sq. Color-coding of all wiring shall be in accordance with IEC 60446. The color of earth wiring cables shall be green with yellow stripes.
Wiring between two terminals shall be continuous. Joints or interconnections at locations other than at terminals are not acceptable. All wiring cables shall be terminated at both ends at a connection terminal. As a minimum requirement, use shall be made of rail-mounted terminals (TS 32 rail assembly) of high-grade Melamine.
When different voltage levels are employed in a single DB enclosure, partitions shall be installed between the terminals of different voltages.
The wiring The wiring ends of stranded conductors which have to be connected into bus type of terminal contacts shall be provided with compression-type pre-insulated wire pins with insulation support.
When cable lugs are used, they shall be of a compression type. To accommodate and support the wiring cables, covered plastic trunking, channels, insulated tubes or plastic strips shall be used. Wiring cables shall never be mounted directly to a metal part of a distribution boards.
The space factor for channels shall never be less than 30 percent. Where supporting of a wiring cable is not feasible, the cable shall be as short as possible.
Note: This anchor post, Free electric installation pictures , may contain a summary of the materials you are looking for. It can be faster than clicking through each post title at the Blog Archive. I started it long ago but never actually got around to finishit.
Copyright http://electricalinstallationblog.blogspot.com/ Electrical DB wiring
Photo 1 - Internal wiring of an electrical DB
Terminals for external conductors All conductor terminals shall be suitable for copper conductors.
All cable termination assemblies shall have facilities for entry of cables from both the top and the bottom of the distribution boards. Cable entries, cable clamping, earthing facilities and supporting devices that are provided shall be suitable for the type, size and number of the incoming cables.
The identification ferrules Both ends of each wiring conductor shall be provided with identification ferrules. The ferrules shall be made of an insulating material of a type not affected by oil or damp. The characters shall be suitably marked in black. (See photo here: Wiring identification ferrules)
The ferrules shall be of the continuous ring type. A slide-on type will not be acceptable. The markings shall be in accordance with the relevant manufacturer’s drawings.
The wiring cables The minimum allowable cross-sectional area of control cables shall be 1.0 mm.sq. Wiring cables with a cross-sectional area of 1.5 mm.sq or larger shall always be stranded. The secondary circuits of current transformers with a 5 A rating shall not be less than 2.5 mm.sq. Color-coding of all wiring shall be in accordance with IEC 60446. The color of earth wiring cables shall be green with yellow stripes.
Wiring between two terminals shall be continuous. Joints or interconnections at locations other than at terminals are not acceptable. All wiring cables shall be terminated at both ends at a connection terminal. As a minimum requirement, use shall be made of rail-mounted terminals (TS 32 rail assembly) of high-grade Melamine.
When different voltage levels are employed in a single DB enclosure, partitions shall be installed between the terminals of different voltages.
The wiring The wiring ends of stranded conductors which have to be connected into bus type of terminal contacts shall be provided with compression-type pre-insulated wire pins with insulation support.
When cable lugs are used, they shall be of a compression type. To accommodate and support the wiring cables, covered plastic trunking, channels, insulated tubes or plastic strips shall be used. Wiring cables shall never be mounted directly to a metal part of a distribution boards.
The space factor for channels shall never be less than 30 percent. Where supporting of a wiring cable is not feasible, the cable shall be as short as possible.
Note: This anchor post, Free electric installation pictures , may contain a summary of the materials you are looking for. It can be faster than clicking through each post title at the Blog Archive. I started it long ago but never actually got around to finishit.
Copyright http://electricalinstallationblog.blogspot.com/ Electrical DB wiring
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