SCOPE OF WORK (ELECTRICAL) - CIDCO Maharashtra Ltd.

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CIDCO OF MAHARASHTRA LTD C.A.No.03/CIDCO/EE(Elect)/2011-12 Sr. Page No. 4.3 All earth electrodes shall be tested for earth resistance by means of standard earth test meter. The tests shall take place in dry months, preferably after a protracted dry spell. If necessary, a number of electrodes shall be connected in parallel to reduce the earth resistance. In such a case the distance between two electrodes shall not be less than twice the length of electrode. 4.4 The electrodes shall have a clean surface, not covered by paint, enamel, grease or other materials of poor conductivity. 4.5 The exact location and number of earth electrodes required at each location shall be determined in the field in consultation with the owner/Engineer-in-charge, depending on the soil strata and resistivity, to meet the ohmic values prescribed in clause 4.3. 4.6 The disconnect facility shall be provided for the individual earth pits to check their earth resistance periodically. 5.0 CONNECTION : 5.1 All electrical equipment is to be doubly earthed by connecting two points on equipment to main earthing ring. The earthing ring will be connected via links to several earth electrodes. The cable armour will be earthed through the cable glands. 5.2 The following shall be earthed. 1. Transformer neutrals (Double Earthing). 2. Transformer Housing. 3. All switchgear and their earth buses.
CIDCO OF MAHARASHTRA LTD C.A.No.03/CIDCO/EE(Elect)/2011-12 Sr. Page No. 4. Motor Frames. 5. Non-current carrying metallic parts of electrical equipment such as switchgear, switch rocks, panel boards, motor control centers, lighting, power and instrument panels, push button stations, cable trays, pipes conduits, terminal boxes etc. 6. All fences/enclosures housing electrical equipment. 7. All still structures, rails etc. including bonding between sections. 8. Shield Wire. 9. Structural steel Columns of building etc. 10. Loading racks. 5.3 System shall be earthed by two distint conductors directly connected to independent earth electrodes which in turn, shall be connected to the earth loop. The earth connection shall be properly made. A small flexible aluminium cable loops to bridge the top cover of the transformer and the tank shall be provided to avoid earth fault current passing through fastening bolts when there is lightning surge, high voltage surge or failure of the bushings. 5.4 Each Lightening Arrestor shall be connected to a separate electrode located as close as possible to it and within he fenced area for each set of arrestors shall be spaced such that they are all within the enclosing fence. Each of these electrodes shall be connected to the main earth grid. 5.5 The shield wire shall be connected with the main grid solidly and net through supporting steel structures. 5.6 All paint, scale and enamel shall be removed from the contact surface before the earthing connections are made.
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SCOPE OF WORK (ELECTRICAL) - CIDCO Maharashtra Ltd.

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