GAIL (India) Limited

10A cover plate at the top of the vertical section shall be provided with necessary ventilating arrangementsAny aperture for ventilation shall be covered with a perforated sheet having less than 1 mm diameterperforations to prevent entry of vermin.3.4 Sheet Steel Cubicle:3.4.1 The sheer steel cubicle shall be designed in fully segregated multitier formation Each cubicle shall havehinged front access door with easy operating fasteners. All the doors and covers shall be heavily gasket tomake the compartment dust tight. Each cubicle shall have a covering at the bottom to make a dust- andvermin roof construction. Door hinges shall be of concealed type.The cubicle shall be of minimum 2mm thick (14 SWG ) sheet steel. Sheet steel shrouds and partitionsshall be of minimum 1.6mm thickness (16SWG). All sheet steelwork forming the exterior of switchboardsshall be smoothly finished, leveled and free from flaws. The corners shall be rounded. The thickness ofGland plates shall be 3mm.3.4.2 The apparatus and circuits in the power control centers shall be so arranged as to facilitate their operationand maintenance at the same time to ensure the necessary degree of safety.Apparatus forming part of the control centers shall have the following minimum clearance.i. Between phases - 25 mm.ii. Between phase and neutral - 25 mm.iii. Between phases and earth - 25 mm.iv. Between neutral and earth - 19 mmWhen for any reason, the above clearances are not available suitable insulation shall be provided.Clearance shall be maintained during normal service conditions. Creepage distances shall comply withthose specified in relevant standards.3.4.3 All insulating materials used in the construction of the equipment shall be non hygroscopic duly treated towithstand the effect of high humidity high temperature and ironical ambient service conditions3.4.4 Functional units such as circuit beakers and fuse switches shall be arranged in mortifier formation, exceptthat not more than One air circuit breaker housed in a single vertical section3.4.5 Metallic/insulated barriers shall be provided within vertical sections and between adjacent sections toensure prevention of accidental contact with:i. Main bus bars and vertical risers during operation, inspection or maintenance of functional unitsand front connected accessories.ii. Cable terminations of one functional unit, when working on those of adjacent unit/units3.4.6 All doors /covers providing access to live power equipment / circuits shall be provided with tool operatedfasteners to prevent unauthorized access.3.4.7 Provisions shall be made for permanently earthing the frames and other metal parts of the switchgear bytwo independent connections.3.5 Metal treatment and finish:All steel works used in the construction of the switch-boards shall have undergone a suitable rigorousmetal treatment process so as to remove oxide scales and rust formation and to facilitate a durable coatingof the paint on the metal surfaces and also to prevent the spreading of rust, in the event of the paint filmbeing mechanically damaged.Two coats of Anti Corrosive primer followed by a finishing coat of Epoxy spray powder coating of theshade 631 of IS: 5 (i.e., Siemens Grey) shall be given. The total thickness of paint shall not be less than 25micron.