Where cables are installed under above suspended ceiling or below ceiling or on wall, they shall be laid on a ladder/perforated G.I. cable tray and shall be run in such positions that they
are not liable to be damaged by contact with the floor or the ceiling or other fixtures.
The ladder/perforated cable tray shall be properly fixed with channels, angles, tie rod, flats to the ceiling. The metal inserts for fixing channels, angles, tie rod, flats shall be put in place while casting the slab. If insert plates are not placed in position, Anchor fasteners shall be used to support cable trays if required. The cable tray route shall be coordinated with other services to avoid crisscross of all the services. While laying the cables on the tray minimum one cable diameter distance shall be observed between two adjacent cables about 20% space shall be kept spare for any future installation.
The trays shall be made of 2mm thick perforated sheet having minimum 75 mm depth.
Addition: NIL Correction: NIL Overwriting: NIL Deletion: NIL AE (E)(P) AE(P) EE (P) The width of perforation shall be maximum 10mm spaced at maximum 20mm
distance. The width of the cable tray shall be selected so as to accommodate required number of cables to be laid on it, with minimum separation of minimum one cable diameter between two adjacent cables. The cables shall be tied with the cable tray with nylon strip/ Aluminium clamps/GI clamps.
Wherever, MS painted cables tray to be used, all steel work shall be treated in accordance with the following procedure and in accordance with IS : 6005 "Code of Practice for Phosphate Iron and Steel".
Oil, grease, dirt and swab shall be thoroughly removed by emulsion cleaning.
Rusting and scale shall be removed by Pickling with dilute acid followed by washing with running water, rinsing with slightly alkaline hot water and over drying.
The phosphate coating shall be sealed by the application of two coats of ready mixed stoving type zinc chromate primer.
After application of the primer, two coats of finishing stove enameled paint shall be applied. The final finished thickness of paint film on steel shall not be less than 50 microns and shall not be more than 100 microns.
Finish painted surface of steel shall present an aesthetically pleasing appearance free from uneven surface.
The finish painting shall be black matt as per ISS or as approved by consultants.
Cables Installed in the Mechanical Room
The cable reaching the motors in the mechanical room or plant room or machines room or service area shall be laid on cable tray except where indicated in masonry underground trenches.
The cable reaching the motors shall be protected by rigid galvanized conduits up to a height of 300mm above the floor. Above that height, the cable shall be protected by means of oil tight flexible metallic G.I. conduits to the terminal box of the motor. The connection between the rigid conduit and the flexible conduit shall be done by a screwed coupling of an approved type. The flexible conduit shall be properly fixed with the terminal box of the motor by means of double hexagonal check nut.
Hot Dipped Galvanized Iron Cable Tray Specification
The cable tray shall be fabricated out of slotted/perforated Hot Dipped Galvanized Iron sheets as channel sections, single or double bended. The channel sections shall be supplied in convenient lengths and assembled at side to the desired lengths. These may be galvanised or painted to the desired lengths. Alternatively, where specified, the cable tray may be fabricated by two angle irons of 50mm x 50mm x 6mm as two longitudinal members, with croses bracings between them by 50mm x 5mm flats welded/bolted to the angles at 1 m spacing. 1.6/2.0 mm thick Stain less steel ( SS-304)/ Hot Dipped Galvanized Iron perforated sheet shall be suitably welded/bolted to the base as well as on the two sides.
Typically, the dimensions, fabrication details etc. are shown in CPWD General Specification for Electrical Works - Part II -External, 1994.
The jointing between the sections shall be made with coupler plates of the same
Addition: NIL Correction: NIL Overwriting: NIL Deletion: NIL AE (E)(P) AE(P) EE (P) material and thickness as the channel section. Two coupler plates, each of minimum 200mm length, shall be bolted on each of the two sides of the channel section with 8mm dia round headed bolts, nuts and washers. In order to maintain proper earth continuity bond, the paint on the contact surfaces between the coupler plates and cable tray shall be scraped and removed before the installation.
The maximum permissible uniformly distributed load for various sizes of cables trays and for different supported span are as per CPWD General Specification of Electrical Work Part II - 1994. The sizes shall be specified considering the same.
The width of the cable tray shall be chosen so as to accommodate all the cable in one tier, plus 30 to 50% additional width for future expansion. This additional width shall be minimum 100mm. The overall width of one cable tray shall be limited to 1200mm.
Factory fabricated bends, reducers, tee/cross junctions, etc. shall be provided as per good engineering practice. (Details are typically shown in figure3) of CPWD General Specification of Electrical Work Part II -1994. The radius of bends, junctions etc. shall not be less than the minimum permissible radius of bending of the largest size of cable to be carried by the cable tray.
The cable tray shall be suspended from the ceiling slab with the help of 12mm dia Electro Galvanized MS rods or 25mm x 5mm flats at specified spacing as per of CPWD General Specification of Electrical Work Part II -1994. Flat type suspenders may be used for channels upto 450mm width bolted to cable trays. Round suspenders shall be threaded and bolted to the cable trays or to independent support angles 50mm x 50mm x 5mm at the bottom end as specified. These shall be grouted to the ceiling slab at the other end through an effective means, as approved by the Engineer, to take the weight of the cable tray with the cables.
The cable tray shall be bonded to the earth Terminal of the switch bonds at both ends.
The cable trays shall be measured on unit length basis, along the center line of the cable tray, including bends, reducers, tees, cross joints, etc, and paid for accordingly.
All accessories like bends, tees, crosses, reducers etc. shall be factory fabricated. Site fabricated will not be accepted.
CABLE TAGS
Cable tags shall be made out of 2mm thick aluminium sheets. Each tag shall be 2” in dia or 3” x 3”
square with one hole of 2.5mm dia, 6 mm below the periphery, or as approved by Consultant. Cable designations are to be punched with letters / number punches and the tags are to be tied to cables with piano wires of approve quality & size. Tags shall be tied inside the panels beyond the glanding as well as above the glands at cable entries. Along trays tags are to be tied at all bends. On straight lengths, tags shall be provided at every 5 meters.
Cables shall be secured to cable trays with 3mm thick x 25mm wide aluminium strips/suitable GI clamp, or as approved by Consultant, at 1000 mm intervals and screwed by means of rust proof screws, washers and bolts, of adequate but not excessive lengths. Cable trays for horizontal runs suspended from the ceiling will be supported with mild steel straps or brackets, at 1000 mm intervals and the overall tray arrangement shall be of a rigid construction. External cabling route marker with GI plate marked with “DANGER 1.1 KV CABLE” with 1 meter long GI angle iron grouting bracket including 1:3:6 ratio cement concrete base block of minimum size 200 x 200 x 350 mm to be provided or as approved by Elect. Supply Company
Addition: NIL Correction: NIL Overwriting: NIL Deletion: NIL AE (E)(P) AE(P) EE (P) CABLING FOR TV SYSTEM:
a) The Co-axial shall be of wide band type with operation capability upto 500 MHz.
b) The ageing resistance of the co-axial cable shall comply with DIN 47252. Part 2, i.e. max. 5%
increase in attenuation at 200 MHz measured by artificial ageing (14 days at 80 deg.C).
EXIT AND OTHER SIGN BOARD
LED type Exit Sign Boards IP-42, single/ Double sided shall be provided near staircase, lift lobby, fire hydrant, Toilets, Water cooler location, sub Station, AC plant, AHUs, STP, DG Set, CCTV Room, Fire Control Room, Entrance, Exit, parking in basement and wherever required as per NBC 2016 with self contained re-chargeable LED lit Laser ETCHED Acrylic signage’s Emergency board with super bright Red, Green LED's having inbuilt re-chargeable battery of Ni-Mh /Ni-cd battery backup of atleast 4 Hrs having wattage less than 2 watts LED lamp fitting housed in Epoxy polyester powder coating acrylic sheet of thickness 8mm with recharging period of 16 - 24 Hrs. with constant current charger having current through LED's under all conditions 20 mA ± 20% and Voltage 3.5V ± 10%, input supply single phase 230 V 50 HZ incorporating indicators showing following features (A) normal supply connected (B) Battery is being charged (C) Circuit continuity exists and confirming to IS: 9583- 1981, with suitable hanging arrangement with SS chain/ directly on wall/ false ceiling as per site requirment.
41.0
TESTING & COMMISSIONINGAs per CPWD Specifications for Electrical Works Part I Internal Electrical– 2013.
UPS
APPROXIMATE/TYPICAL - DETAILS OF UPS LOAD UPS Load
Lighting Load for basements = 0.25 kW
Lighting Load for Upper Floors = 1.00 kW
Total Lighting Load = 1.25 kW
UPS Points for PCs = 18 kW
Total Lighting & PC Load on UPS = 19.25 kW
10% Future Provision = 1.90 kW
Total Load on UPS = 21.15 kW
Total Load on UPS = 26.43 kVA
Proposed Capacity = 3x10KVA (2W+1S)