Indian Standard Code-Abstract (IS:1554/IS:15652/IS:1678/IS:1255/IS:694
Abstract of IS 1554 | |
| Insulation Color (up to 11 KV) | For reduced neutral conductors, the insulation color shall be black |
| Arrangement of Marking (up to 11 KV)
| For cables having more than 5 cores, the core identification may be done by numbers. In that case, the insulation of cores shall be of the same color and numbered sequentially, starting with number 1 for the inner layer. The numbers shall be printed in Hindu-Arabic numerals on the outer surface of the cores. All the numbers shall be of the same color which shall contrast with the color of the insulation. The numerals shall be legible. |
| When the number is a single numeral, a dash shall be placed underneath it. If the number consists of two numerals, these shall be disposed one below the other and a dash placed below the lower numeral. The spacing between consecutive numbers shall not exceed 50 mm. | |
| Type of Armor (up to 11 KV)
| Where the calculated diameter below armoring does not exceed 13 mm, the armor shall consist of galvanized round steel wires. Where the calculateddiameter below armoring is greater than 13 mm, the armor shall consist of either galvanized round steel wires or galvanized steel strips. |
| Cable Identification/ Marking (up to 11 KV)
| Type of Cable Legend: (i) Improved fire performance or Category C1 FR ( Cables in constrained areas, Does not propagate fire even when installed in groups in vertical ducts),(ii) Improved fire performance for Category C2 FR—LSH (Cables in constrained areas with limited human activity and/or presence of sophisticated systems) |
| Aluminum conductor= A, PVC insulation=Y, Steel round wire armor= W, Steel strip armor= F, Steel double round wire armor= WW, Steel double strip armor =FF, PVC outer sheath= Y | |
| Insulating Rubber Mat | Four classes of mats, covered under this standard nd differing in electrical characteristics for different use voltages are designated |
| Insulating Rubber Mat | Class = AC (Rms)KV=DC(V)=Thickness(mm) A=3.3=240= 2.0 B=11= 240=2.5 C=33=240=3.0 D =66= 240=3.5 |
| Insulating Rubber Mat | Most of all classes hall be resistant to acid and oil and low temperagre and shall be identified by the respective class symbol. However a category with special property of resistance to extreme ‘low’ ternperature will be identified by a subscript’s ‘to, the ‘respective “c” Class symbol |
| Insulating Rubber Mat | Roll of Mat shall be in multiple Length of of 5000mm and ion width of 1000mm.Standard Shape in length of 1000, 2000, 3000mm. |
| Insulating Rubber Mat | Leakage current for all Class of Mat shall not be more than 10 Micro Amp. |
Abstract of IS: 15652 for Insulating Mat | ||||
| Insulating Rubber Mat
| Class | AC Voltage | DC Voltage | Thicknes |
| Class A | AC (Rms)KV=3.3 | DC(V) =240 | 2.0mm | |
| Class B | AC (Rms)KV=11 | DC(V) =240 | 2.5mm | |
| Class C | AC (Rms)KV=33 | DC(V) =240 | 3.0mm | |
| Class D | AC (Rms)KV=66 | DC(V) =240 | 3.5mm | |
| Class A | AC (Rms)KV=3.3 | DC(V) =240 | 2.0mm | |
| Resistance | Most of all classes hall be resistant to acid and oil and low temperature and shall be identified by the respective class symbol. However a category with special property of resistance to extreme ‘low’ ternperature will be identified by a subscript’S ‘to, the ‘respective “C” Class symbol. | |||
| Length | Roll of Mat shall be in multiple Length of 5000mm and ion width of 1000mm.Standard Shape in length of 1000, 2000, 3000mm. | |||
| In Case of Mat in Roll It shall be min 1m X 1m. | ||||
| Leakage current | Leakage current for all Class of Mat shall not be more than 10 Micro Amp. | |||
Abstract of IS: 1678 for Pole | |||
| PCC Pole | Class of Pole | Length of Pole | Min Ultimate Transverse Load |
| Class 1 | 17 Meter | 3000 Kg | |
| Class 2 | 17 Meter | 2300 Kg | |
| Class 3 | 17 Meter | 1800 Kg | |
| Class 4 | 17 Meter | 1400 Kg | |
| Class 5 | 16 Meter | 1100 Kg | |
| Class 6 | 12.5 Meter | 1000 Kg | |
| Class 7 | 12 Meter | 800 Kg | |
| Class 8 | 12 Meter | 700 Kg | |
| Class 9 | 11Meter | 450 Kg | |
| Class 10 | 9 Meter | 300 Kg | |
| Class 11 | 7.5Meter | 200 Kg | |
| PCC Pole Tolerance | Tolerance: The tolerance of overall length of the poles shall be + 15 mm. | ||
| The tolerance on cross-sectional dimensions shall be + 3 mm. | |||
| The tolerance on cross-sectional dimensions shall be + 3 mm. | |||
| The tolerance on uprightness of the pole shall be 0.5 per cent | |||
| PCC Pole depth in Ground:
| Length of Pole | Min depth in ground | |
| 6 Meter To 7.5 Meter | 1.2 Meter | ||
| 8 Meter To 9 Meter | 1.5 Meter | ||
| 9.5 Meter To 11 Meter | 1.8 Meter | ||
| 11.5 Meter To 13 Meter | 2.0 Meter | ||
| 13.5 Meter To 14.5 Meter | 2.2 Meter | ||
| 15 Meter To 16.5 Meter | 2.3 Meter | ||
| 17 Meter | 2.4 Meter | ||
Abstract of IS :1255 for Installation of Cable | |
| Cable Route Indicator (Up to 33KV) | Power cable route indicators should be provided at an interval not exceeding 200 M and also at turning points of the power cable route wherever practicable |
| Cable Corrosion (Up to 33KV) | Electrolytic corrosion: Where the possibility of electrolytic corrosion exists, for example, adjacent to dc traction system, the potential gradient along the pipe-line and the cable sheath should be specified. |
| Neutral (Up to 33KV) | The neutral point is earthed in such a manner that during a line-to-earth fault the highest rms voltage to earth of a sound phase(s) expressed as a percentage of the highest line-to-line voltage, does not exceed 80 percent, irrespective of the fault location, |
| Earthing (Up to 33KV) | The neutral point is not earthed but a device is installed which automatically and instantly cuts out any part of the system which becomes accidentally earthed, |
| Earthing (Up to 33KV) | In case of ac systems only, the neutral point is earthed through an arc suppression coil with arrangement for isolation within one hour for the non-radial field cables and within 8 hours for radial field cables, of occurrence of the fault provided that the total of such periods in a year does not exceed 125 hours. |
| Cable Tensile Strength (Up to 33KV) | PVC and XLPE insulated armored power cables P = 9 D2 ,P=Pulling Strength(N),D=Outer Dia of Cable(mm) |
| Cable Tensile Strength (Up to 33KV) | PVC and XLPE insulated unarmored power cables P = 5 D2 |
| Cable Tensile Strength (Up to 33KV) | Paper insulated armoured power cables P = 5 D3 |
| Cable Pulling (Up to 33KV) | For Cables Pulled by Pulling Eye : If the cables are pulled by gripping the conductor directly with pulling eye, the maximum permissible tensile stress depends on the material of the conductor and on their cross-section as given below: For aluminum conductors 30 N/mm2 and For copper conductors 50 N/mm2 |
| Cable Pulling (Up to 33KV) | Expected Pulling Force When Pulling Cables by Winch : The following values of pulling force are expected = (approximately percentage of cable weight): In trenches without large bends 15-20 % |
| Cable Laying Direct in Ground (Up to 33KV) | This method involves digging a trench in the ground and laying cable(s) on a bedding of minimum 75 mm riddled soil or sand at the bottom of the trench, and covering it with additional riddled soil or sand of minimum 75 mm and protecting it by means of tiles, bricks |
| Cable Laying Direct in Ground (Up to 33KV) | Depth : The desired minimum depth of laying from ground surface to the top of cable is as follows: High voltage cables, 3.3 kV to 11 kV rating =0.9 m High voltage cables, 22 kV, 33 kV rating= 1.05 m Low voltage and control cables = 0.75 m Cables at road crossings = 1.00 m Cables at railway level crossings (measured from bottom of sleepers to the top of pipe)=1.00m |
| Cable Clearance (Up to 33KV) | Clearances :The desired minimum clearances are as follows: Power cable to power cable = Clearance not necessary; however, larger the clearance, better would be current carrying capacity Power cable to control cables = 0.2 m Power cable to communication cable = 0.3 m Power cable to gas/water main = 0.3 m Inductive influence on sensitive control cable on account of nearby power cables should be checked |
| Cable Clearance (Up to 33KV) | The power cable should not be laid above the telecommunication cable, to avoid danger to life of the person, digging to attend to the fault in the Telecommunication cable. |
| Crossing (Up to 33KV) | Cables Laid Across Roads, Railway Tracks and Water Pipe Lines: Steel, cast iron, plastics, cement or earthenware ducts, or cable ducting blocks should be used where cables cross roads and railway tracks. Spare ducts for future extensions should be provided. Spare duct runs should be sealed off. Buried ducts or ducting blocks should project into footpath or up to the edge of road, where there is no footpath, to permit smooth entry of cable without undue bending |
| Diameter of Pipe (Up to 33KV) | The diameter of the cable conduit or pipe or duct should be at least 1.5 times the outer diameter of cable. The ducts/pipes should be mechanically strong to withstand forces due to heavy traffic when they are laid across road/railway tracks. |
| Bending Radius (Up to 33KV) | The bending radius of steel or plastics ducts should not be less than 1.5 m. |
| Cable on Over Bridge (Up to 33KV) | Cable Over Bridges : On bridges, the cables are generally supported on steel cable hooks or clamped on steel supports at regular intervals. While designing a cable layout on a bridge; expansion of bridge due to changes in atmospheric temperature should be taken into account. On most of the rail-cum-road bridges, the cables are subjected to vibrations. For such conditions, round wire armoured and lead alloy ‘B’ sheathed cables are preferred. Cables can be laid on bridges duly suspended from catenary wire at regular intervals |
| Cable on Railway Crossing (Up to 33KV) | Cables Below Railway Crossing : When the cables are laid under railway tracks the cables should be laid in reinforced spun concrete or cast iron or steel pipes at such depths as may be specified by the railway authorities but not less than 1 m measured from the bottom of sleepers to the top of the pipe. |
| Cable on Duct (Up to 33KV) | On long run ducts, it is desirable to apply lubrication to the lead or serving/outer sheath as it enters the duct. Petroleum jelly or graphite powder or a combination of both is effective for this purpose and through lubrication will reduce the pulling tension by about 40 percent. |
| Laying on Racks in Air (Up to 33KV) | Lying on Racks in Air-The vertical distance between the two racks should be minimum 0.3 m and the clearance between the first cable and the wall (if racks are mounted on wall) should be 25 mm. The width of the rack should not exceed 0.75 m in order to facilitate installation of cables. |
| Laying on Racks in Air (Up to 33KV) | Ungalvanized steel work of cable racking/trays should be painted with a coat of primer and thereafter finished with suitable anti-corrosive paint. |
| Laying on Racks in Air (Up to 33KV) | Only single-core cables laid on horizontal racks need be clamped at suitable intervals. Multi-core cables need not be clamped. The distance between the vertical clamps should not be more than 2 m. |
| Laying Cables on Racks Inside a Tunnel(Up to 33KV) | Laying Cables on Racks Inside a Tunnel: Horizontal distance between Two cable is min Diameter of Cable and vertical distance between two cable row is 30cm.In cable tunnel, the head room should not be less than 2 m and width sufficient to leave a free passage of at least 600 to 800 mm either from one side or in the middle. |
| Laying Cables on Racks Inside a Tunnel(Up to 33KV) | With temperatures below 3°C, the cables should be warmed before the laying out, since otherwise the bending would damage the insulation and protective coverings of cables. The cable laying must be carried out swiftly, so that the cable does not cool down too much |
| Laying Cables on Racks Inside a Tunnel(Up to 33KV) | Identification strips/tags of metal or plastics should be attached to the cables, particularly if several are laid in parallel, 8 to 10 m apart. Identification tags should also be attached at every entry point into the buildings and at the cable end termination |
| Laying Cables on Racks Inside a Tunnel(Up to 33KV) | The spacing between three cables laid in one plane should be not less than the cable diameter. |
| Laying Cables on Racks Inside a Tunnel(Up to 33KV) | When the cable run is several kilometres long, the cables should be transposed at one-third and at two-thirds of the total lengths. |
| Trefoil arrangement in ducts (Up to 33KV) | If several single-core cables are laid per phase, these should be arranged as follows to ensure balanced current distribution in Horizontal direction : R-Y-B-Distance-B-Y-R, (Distance=2 X Diameter of Cable) , vertical distance shall be 6 X Diameter of Cable |
Abstract IS 694 (Cable) | |
| Cable Sheath (Up to 1.1KV)
| The color of the sheath shall be black or any other color as agreed to between the purchaser and the supplier. For weatherproof cables, the color of sheath shall be black only. |
| The difference between maximum and minimum measured values of overall diameter of sheathed circular cables shall not exceed 15 percent of the maximum measured value at the same cross-section. | |
| Cable Construction (Up to 1.1KV)
| Copper Cable up to 6mm2 =Solid/Stranded , |
| Copper Cable up to 10mm2 =Solid/Stranded | |
| Copper Cable above 6mm2 =Stranded , | |
| Copper Cable above 10mm2 =Stranded | |
| Cable-Testing (Up to 1.1KV)
| The core(s) shall be carefully removed from a sample approximately 3 m long from the finished cable. They shall be so immersed in a water-bath at 60±3ºC that their ends protrude at least 200 mm above the water-level. After 24 hours, a voltage of 3 kV (rms) shall be applied between conductors and water. This voltage shall be raised to 6 kV (rms) within 10 seconds and held constant at this value for 5 minutes. If the sample fails in this test, one more sample shall be subjected to this test, which should pass. |
| The cores which have passed the preliminary test given in 16.2.1 shall be subsequently tested with a dc voltage of 1.2 kV in the same water-bath at the same temperature. The conductors shall be connected to the negative pole and water to the positive pole of dc supply by means of a copper electrode. | |
| The core shall withstand this dc voltage test for 240 hours without breakdown. | |
| The voltage shall be applied continuously, but if there are any unavoidable interruptions during the 4 hours period, that period shall be increased by the time of interruptions. The total of such interruptions shall not exceed 1 hour otherwise the test shall be started again. | |
| The cables and cords shall withstand without breakdown an ac voltage of 3 kV (rms) or a dc voltage of 7.2 kV applied for a period of 5 min for each test connection | |
| Single-core cables shall be immersed in water at ambient temperature one hour before the testing and the test voltage shall be applied between conductor and water for the specified period. | |