Lighting Distribution Boards (LDB) are an integral and essential part of every building project and it must be designed, manufactured and installed all in accordance with the safety standards. In most of the cases it operates a layman wherein others operate dedicated or trained person. This article explains what are the essential standards, parts, frame to be applied for manufacturing and installation of lighting distribution boards in a quality building project.
1. Scope of LDB Work
The scope of this specification covers supply, installation, testing and commissioning of distribution boards with CB or HRC fuses for lighting fixtures.
2. Applicable Standards
The following standards shall be applicable however, contractor shall comply with the latest or superseded versions of IS/BIS to be used for the complete work:
IS 4064-1978: Heavy Duty Fuse Switch
IS 2675-1966: Distribution Fuse Boards.
IS 8828-1978: Miniature Circuit Breakers.
IS 9224-1979: High Rupturing Capacity Fuse Links.
3. Construction of Lighting Distribution Boards (LDB)
- The LDB shall be constructed out of 1.6 mm thick sheet steel.
- The LDB shall be preferably wall mounting, indoor type with proper gaskets at doors and joints to ensure dust and vermin-proof enclosures.
- The top and bottom of the DB shall have removable glad plates for conduit entries. In case, the DB are to have an incoming feeder of switch fuse unit then this feeder shall be in a separate compartment, with proper barriers between incoming and outgoing feeders. For easy spread of cables adapter boxes on DB should be provided.
- The phase busbars shall be of 100 Amps minimum, preferably tinned copper. The neutral busbar shall be of tinned copper with adequate number of punching type screw terminals. Adequate space shall be provided at the top and bottom to facilitate easy termination of incoming and outgoing cables.
- The earthing terminals shall be provided.
4. Fuses in LDB
The fuses shall be of HRC cartridge fuse link type having a certified - rupturing capacity of not less than 46 KA at 415 Volts AC. The HRC fuses shall conform to IS 9224-1979. All fuses shall have a visible indication to indicate a 'blown' condition. The tags of the fuses shall be of the plug-in type or of the bolting type.
5. HRC Fuse Carriers in LDB
The HRC fuse carriers/bases shall be of high grade phoenolic moldings. The contacts shall be silver plated and the contact block shall be suitable to receive the rated conductors of aluminium.
6. Miniature Circuit Breakers MCB in LDB
The CB shall be of single pole, double pole, triple pole or four pole as required. The CB shall be of thermal magnetic type with a rupturing capacity of 9 KA at 415 V.
7. Industrial type Plugs and Sockets
Industrial type plugs and sockets shall be constructed out of non-corroding die cast aluminium alloy. The contact tubes of the sockets shall have the facility of self-alignment and easily removable from the base for wiring. The plugs shall have robust contact pins, with a grid pin to ensure non-reversibility. The plugs shall have a rubber cable guard at the point of entry.
8. Testing of LDB
- High Voltage Test at 2.5 KV
- Power and Control Circuits Continuity Test.
- Insulation Resistance Test with 1000 V Meggar.
- Operational Test.
- Three sets of test certificate to be submitted.
9. Drawing and Date of LDB
Three sets of General Arrangement Drawings and Wiring Diagrams of all type of Feeders shall be submitted.