PVC PILC XLPE MICC cable installation

The following sample specifications covers the installation of PVC, XLPE, PILC and MICC cables in a new high-rise office building.

Photo 1 – Electric cables installed on cable tray


UPDATE March 18, 2011: As part of the re-construction process of this blog, I will gradually upload photographs of real installations of electrical works.

The photos will be attached to the relevant existing posts when that is possible.

If the original article is in the form of specifications like the one below, having pictures and images in the middle of it may spoil the structure of the article. In that case I may send a new post to load the photographs.

Then I will create a hyperlink in the existing post to connect to the new post and the photos.

Of course the new post will also be hyperlinked back to the original post so the readers will not lose their way trying to come back to the article he/she was previously reading.

The uploading takes time and I will do it gradually. In the process, the article will look half-completed and definitely not nice-looking.

However, I set up this blog to give readers contents. Lots of contents. If you are looking for a nice-looking blog, this is definitely not a right place.

SCOPE
The scope of this section is to set out the materials, requirements, methods, workmanship, standards and regulations in connection with the cable installation works.

TYPE OF CABLES
PVC insulated armored cables (PVC/SWA/PVC)
Cables shall be PVC insulated, steel wire armored, PVC sheathed overall and shall be manufactured and tested in accordance to the specifications of BS 6346. They shall be of the 600/1000 volts grade with high conductivity copper conductor.

XLPE insulated cables
Cross-linked polyethylene insulated cables shall be suitable for 1000 volts with high conductivity copper conductor. They shall be manufactured and tested in accordance with to the specifications of B.S. 5467.

For 11000/ 33000 volts applications, the cable shall be manufactured and tested according to the specifications of B.S. 6622:1985.

For normal operation, XLPE insulated PVC sheathed (XLPE/PVC) cables shall be employed. For underground applications XLPE insulated, steel wire armored, PVC sheathed (XLPE/SWA/PVC) cables shall be used.

Paper insulated cables
The manufacturing of mass-impregnated, non-draining type paper-insulated and lead-alloy sheathed (PILC) cables shall fully comply with the requirements of BS 6480. Unless otherwise specified, PILC cables shall be insulated for 1000 volts with high conductivity copper conductor.

For underground distribution, PILC cables with steel tape armored and served overall (PILCSTA&S) shall be employed.

Mineral insulated cables
Mineral insulated copper sheathed (MICC) cables shall be manufactured and tested in accordance to BS 6207 and shall be of the heavy-duty type of 1000 volts. The cables consist of high conductivity copper conductors, embedded in pressure packed magnesium oxide insulation within a robust, ductile, seamless copper sheath.

For situations corrosive to copper and underground installation, MICC cable with PVC sheath shall be used.

CABLE HANDLING
The most important point to observe in handling cables is that great care must be exercised at all times.
Every precaution should be taken to avoid dropping a drum of cables. Dropping, even from a short height, will flatten the layers of cable nearest to the barrel of the drum due to the weight from the outer layers. Similar distortion will also occur if the drum falls on its sides.

When rolling the drum into position it is essential that the drum rolls smoothly in the direction of the arrow painted on the side of the drum. If this instruction is not followed, slack cables will tend to accumulate towards the inner turns and may result in damages to the cables.

Wooden battens around the cable drum should be very carefully removed. Suitable tools should be used for this purpose.

When a drum is in position, it should be mounted on jacks and disposed so that the cable is pulled off from the bottom and not over the top.

It is preferable to mount the drum at one end of the cable run as close as possible to the edge of the cable trench so that the cable can be pulled off in a continuous manner on rollers in trench and is in its final position when the last turn leaves the drum. This procedure is not always possible because of the excessive length and weight of the cable run or because of obstruction or pipes under which the cables have to be threaded.

In such cases it may be necessary to position the drum at some other point along the cable run and lay off the cable on the ground near the drum in a series of loops, one above the other in the form of a figure eight, crossing the cable back and forth on itself.

When the whole length has thus been removed from the drum the inside end of the cable will be on top and can be pulled along towards its final position on rollers in the same manner as if the cable was coming off the drum itself. Whichever procedure is adopted great care must be taken at all times to ensure that cable is not twisted and that the turns are well above the minimum bending radii of cable. The radii of cable below 22 kV may be taken as follows:

For sizes up to 50 mm overall diameter – Min bending radii: 12 x diameter
For sizes 50 mm and above overall – Min bending radii: 20 x diameter

Wire cable stockings with an eye at one end should always be used with pulling ropes. Ropes should never be tied directly to the cable ends.

RE-DRUMMING OF CABLES
Owing to deterioration of cable drums, it is sometimes necessary to transfer cables to another drum. Steps to do this should be taken immediately when signs of the drum deterioration become evident and on no account must the transfer be delayed until the drum is on the point of collapse as so often happens.

Both drums should be jacked off the ground and the cable slowly wound from one drum to the other with the cable bending in the same direction on the new drum as on the old one.

Great care must be taken to ensure that the radius of the new drum barrel is not less than the minimum bending radius of the cable. As arrow should be painted on the side of the new drum to indicate the direction in which the drum was turned during rewinding operations i.e. the direction in which the drum should be rolled. The words “REWOUND CABLE” should also be clearly painted in Red on both sides of the drums.

The re-drumming of cables will only be carried out under the direct supervision of the S.O.’s Representative.

INSTALLATION OF CABLES

General
All cables shall be terminated in cable boxes or sockets of suitable size for the cable employed without excessive clearance.
The spacing of the cable supports shall be determined by the size of cable and in the case of cables of less than 25 mm in overall diameter the spacing shall not exceed 760 mm.

All cables shall be supported in such a manner as to unsure that they do not sag after erection and their means of support shall be to the approval of the S.O.’s Representative. Fixing shall be made with raw bolts or other patent fixing devise of design approved by the S.O.’s Representative.

Where cables enter or leave cable pipes or ducts, the entries shall be sealed effectively by means of close fitting solognum impregnated split wooden plugs and a mixture of compound and transformer oil or other approved method in order to prevent the ingress of water or dirt.

All cables passing through interior walls or floors shall be sealed effectively to the approval of the S.O.’s Representative by means of asbestos cement after the cables have been pulled through in order to prevent accumulation of moisture and the ingress of debris, sand and vermin.

All cables shall, where they pass through floors or otherwise in such positions vulnerable to damage by mechanical or other means shall be protected by short length of steel pipe suitable bushed to prevent abrasion of the cable.

Straight and tee joints
Straight and tee joints in any of the cables installed under this contract will only be permitted in very exceptional circumstances and only with the S.O.’s Representative approval in writing. The cost of such straight and tee joints, if permitted by the S.O.’s Representative shall be born by the contractor unless such joints are arising from unavoidable limitations in manufacturing lengths or from alterations in routes after initial approval.

Cable pulling
Winching of cables through ducts shall only be carried out with the approval of the S.O.’s Representative in which event a pulling eye shall be attached to the conductors.

A cable sheath stocking may be employed on cables where undue stress in the sheath is likely to occur.

Underground cable boxes
Straight through and tee underground joint boxes shall comprise a good quality, cast iron, split type box complete with nuts and bolts and accommodating a lead sleeve or case suitable for plumbing to the cable sheath. Boxes shall be free from blowholes and provided with compound filling holes and plugs. Internal and external box surfaces shall be painted with an approved preservative compound.

Boxes shall be provided with armor clamps and provision shall be made for bonding the steel wire armoring across the joint and on to the lead sheath or case. The bond shall comprise a tinned copper conductor and in no case shall it have a cross section area less than that of the largest conductor.

Lead sleeves shall be formed from solid drawn tubes and lead cases for three and four way joints shall be made from lead sheet halves rebetted and soldered together on completion of the joint. Lead sleeves and case shall be free from porosity and impurities, of adequate thickness, complete with filling holes and lead seals.

Core numbers printed on papers shall be strictly observed when jointing and such numbers shall be maintained throughout the system. Papers numbered ‘0’, ‘1’, ‘2’, and ‘3’ shall be identified as neutral, red, yellow and blue phases respectively and in the case of two core cables number ‘1’ shall be the phase conductor and ‘0’ the neutral.

Crossing of cores in boxes shall be avoided wherever possible but connections shall be consistent with the foregoing requirements.

Sealing end boxes
Box shall be of the split type with effectively sealed joint surfaces and manufactured from good quality cast iron free from blow holes with screwed plug filling and venting holes of ample dimensions and of such design as to permit continuous filling in one operation in order to avoid the formation of voids.

Box shall be painted internally and externally with an approved preservative compound and shall be complete with brass cone shaped wiping gland, armor clamp, fixing lugs and earth continuity bond across the box from armor clamp to equipment frame.

The top plate shall be tapped for conduit entry or fitted with bushing insulators as appropriate to the situations.
Where means of cable support is not provided within the equipment, or in any situation, the contractor shall provide adequate cable support below the sealing box in order to relieve the joint and the box of stress.

Where it is not possible to fix cable to the framework or supporting members specifically supplied for the purpose in or on apparatus, then the contractor shall supply and install to the satisfaction of the S.O.’s Representative such support fabricated from galvanized steels as may be necessary.

Boxes shall be of such design that they are suitable for attachment to the equipment served and shall allow cable conductors to be formed into the equipment terminals without distortion.

PVC or XLPE insulated armored cables

Jointing of PVC/SWA/PVC or XLPE/SWA/PVC cables shall be carried out by accredited and fully experienced jointers and evidence of this shall be produced to the satisfaction of the S.O.’s Representative before jointing is started.

All terminal sealing boxes, cable cores shall be carried through unbroken to apparatus terminals and cores shall sweat solid where they pass through cast resin.

All joint boxes, jointing materials and tools shall be of the type recommended ans manufactured by the cable supplier.
All joints which are buried in the ground shall be compound filled. The design of the box and the composition shall provide an effective seal to prevent moisture gaining access to the conductor ferrules and armor clamps.

Provisions shall be made for earthing the wire armor to the main electrode at the supply and by means of a metallic bond of adequate conductance, and the bonding connection should be as short and straight as possible.

The wire armoring shall be maintained electrically continuous and careful attention shall be paid to the design of all bonding clamps in joints and terminations to ensure that the resistance across a clamp is not higher than that of the equivalent length of the complete wire armor of the cable.

The conductance of the carcase of cast iron is normally sufficient for this purpose but, where it falls short, an auxiliary metallic bond shall be included.

Compression type glands for the terminations of cables will normally be included with the terminating boxes. Marshalling and other terminating boxes supplied under this contract, however, shall include the terminating cable glands.

The design of compression glands shall be such that the cable is not twisted when the gland is tightened. They shall provide facilities for the efficient bonding and termination of the armor wires and shall project at least 20 mm into the terminating box so that any condensation collected on the inner surfaces of the boxes cannot flow down between the cable cores. Where anti-condensation heaters are not fitted, drain holes shall be provided. It is possible to erect and dismantle any cable compression gland without the use of special tools.

Paper insulated cables
Jointing of PILC cables shall be undertaken only by by an accredited and fully experienced jointer and evidence of this shall be produced to the satisfaction of the S.O.’s representative before jointing is started.

At terminal sealing boxes, cable cores shall be carried through unbroken to terminal apparatus.

Every cable joint shall be started and finished during the same day and whenever cables are to be joined in the open during wet weather conditions, suitable precautions shall be taken to preclude ingress of moisture into the cable joint.

Joint and sealing boxes shall be thoroughly flame warmed on the outside of the box before pouring compound and compound temperature shall be checked frequently by the use of a suitable scaled and protected thermometer to ensure that the pouring temperature does not exceed the manufacturer’s recommendations and that overheating does not occur.

Whenever PILC cable is cut during the course of insulation, the open ends shall be sealed immediately, unless jointing is to follow, by means of a lead cap wiped to the sheath to form an air tight seal. Under no circumstances should PILC cables be sealed with insulating tapes.

PILC cables must be tested for moisture before jointing is commenced. Samples of paper both from the layers nearest to and furthest from the conductor should be immersed in transformer oil or paraffin wax, this will be immediately detected by bubbling. Samples of paper should be tested singly and should not be touched by hand but gripped in a pair of tweezers.

Testing of insulation resistance
An insulation resistance test should be made to each length of cable laid before jointing is commenced.

MICC cables
Insulation and continuity tests shall be carried out before and after MICC cable is installed using a 500 volt “megger” and this must result in an “infinity” reading, no lower value will be accepted. A blow lamp may be used for drying out cut cable ends if it is impracticable to cut to waste in which event the cable should be brought to cherry red heat at about 600 mm from the end and moisture carefully driven towards the cut end.

Minimum bending radius shall not be less than six times the cable diameter and saddle spacing not less than 60 times the cable diameter and nor greater than 760 mm whichever is the less.

An unsupported loop shall be left in the cable at terminations subject to vibration.

It is essential that the greatest care shall be taken to ensure that hands and all materials, particularly the compound are perfectly dry and clean when terminating MICC cables. The length of tails shall be kept to a minimum.

Dirt and metallic particles in the compound and any loose traces of dielectric left at the face of the sheath after stripping shall be carefully removed, prior to sealing.

Cold sealing compound shall be forced down one side of the pot and up the other at the same time “overfilling” in order to avoid trapping air at the base of the pot and to ensure that when the sealing disc is entered before crimping a completely solid insulation barrier is effected.

Electricians employed on termination of MICC cables shall be fully instructed and experienced in the stages of the operation and work will be stopped, if in the opinion of the S.O.’s Representative insufficient care and/or skill is not being exercised particularly in this phase of the work.

TESTING
The contractor shall be responsible for the testing of the cables and certifying that they are safe before the supply is switched on. Tests shall include continuity, phasing out and insulation resistance between conductors and between conductors and sheath employing 500 volts “megger” tester of other approved type tester. Voltage tests to prove the soundness of the protective servicing and continuity test to prove the soundness of the wire armoring. A copy of test results shall be submitted to the S.O. before the cables are energized.

FIRE RESISTANT CABLES AND INSTALLATION
Fire resistant cables shall be of 300/500 volts and 600/1000 volts and suitable for surface wiring and installation in conduit or duct.

Cables shall both fire resistant and flame retardant to IEC 331 and IEC 332 respectively. The cables shall also be tested for resistance to fire and water and mechanical shock to categories C, W and Z of BS 6387. The outer sheath shall be halogen free under IEC 754 Part 1. Test certificates to substantiate the compliance shall be submitted.

Cables shall be made of stranded, soft annealed copper conductor to IEC 228, mica tape fire barrier, insulation of cross-linked polyethylene with continuous conductor temperature of 90 degree Centigrade conforming to IEC 502 and outer sheath made of flame retardant low smoke and non-halogen polyethylene. Core identification of cable shall be by color of the insulation according to IEC 502. The maximum resistance of the conductors at 20 degree Centigrade shall not exceed that specified in IEC 228. The cables shall be FUJIKURA brand or equivalent.

Cables shall be suitable for installation by conventional methods without requiring expensive tools, seals or terminations. The accessories shall be non-hygroscopic, maintenance free and insensitive to vibrations. When installed on the cable trays, the spacing of saddles and the arrangement of cables shall be in accordance with the relevant BS or IEC standards. Minimum bending radius shall not be less than 6 times of the outer diameter of the cables.

The cables shall comply fully with the requirements of the Fire Department and relevant approval letter shall be submitted.
Note: This anchor post, Free electric installation pictures , may contain a summary of the materials you are looking for. It can be faster than clicking through each post title at the Blog Archive. I started it long ago but never actually got around to finish it.

RELATED ARTICLES: 1) Intro to XLPE armored cables;

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Electrical switchboard installation

The following is a sample perfomance specifications for the assembly and installation of switchboards in an electrical contract for a new multi-storey office building.

Scope
The scope of this section is to set down briefly the requirements, methods, materials, workmanship, standards and regulations in connection with the complete assembly of switches, starters, and/ or control devices as used in an electrical installation.

Standard of manufacture
The equipment shall comply in every respect with the requirements of the latest edition of B.S. and M.S. specifications and be approved by the Director General, Office of Energy Commission. Switchboards, distribution boards and feeder pillars fabricated by manufacturers unauthorized or unregistered with the Director General, Electricity Supply Board, will not be accepted.

Copies of Type Tested Certificate issued by A.S.T.A. or other approved testing authorities shall be submitted together with the tender.

Electrical system
All switchgear under this section is for use on 415/240 volts, 3 phase 4 wire, 50 Hz alternating current system with solidly earth neutral.

Rupturing capacity
The switchboard shall be capable as a whole of withstanding without damage the electrical, mechanical and thermal stress produced under short circuit conditions, equivalent to 31 MVA at 415 volts for 1 second as defined in BS 5486.

Construction of switchboards
The switchboard shall be modular, cubicle metalclad, self contained, extensible, flush mounted, floor or wall mounted as specified, easily accessible and suitable for housing the individual switchgear and other necessary electrical accessories as specified hereinafter or on the drawings.

The switchboard is to be adequately ventilated and be designed to prevent ingress of all vermin, accidental contact with live parts and to minimize the ingress of dust and dirt. Precaution shall be taken to prevent overheating through hysteresis and eddy current loss.

Extensive labeling and marking shall be used in internally and externally in each switchboard in accordance with the drawings indicating the rating function, designation, number and/ or code letter of the equipment, switches, circuit breakers, fuses, indicating lights etc.

All switchboards must be rested on 100 mm high plinths.

Framework of switchboards
The framework of the switchboard cubicle shall be fabricated from rolled steel angle sections and shall be self-supporting when assembled. The switchboard shall be of rigid construction designed to withstand without any sag, deformation or warping, the loads likely to be experienced during normal operation, maintenance, transportation or maximum fault conditions. All structural members shall be folded on 12 SWG sheet steel. The front door and instrument panels shall be constructed of 12 SWG sheet steel pressed or rolled so that the edges are given a neat round finish. The doors and panels seated on a rubber gasket cemented to the frame. The sides, rear and top panels shall be constructed of 14 SWG sheet steel.

Paint finish and anti corrosion protection
The cubicle framework and sheet steel panels shall be chemically cleaned, degreased and lithoform etched prior electrostatically power sprayed with epoxy paint and oven baked to a touch and smooth finish coating.

All screws, bolts, nuts, washers and similar materials used shall be chromium plated.

Distribution boards
All distribution boards shall be completely enclosed in dust, splash, insect and vermin proof metalclad cubicles and their lids secured with knurled thumb screw. Fuse switches, isolators, contactors, busbar, meters, fuses, or miniature circuit breakers shall be provided as specified on the drawings. Earth terminal blocks, phase barriers, labels and charts for outgoing circuit identification shall be provided.

The distribution boards shall be designed for operation on a 415/ 240 volts, 50 Hz, A.C. system and generally comply with B.S. 214 and suitable for wall, floor or flush mounting as shown on the drawings.

The general construction of frame and panel shall be as specified under clause 5 and 6 but the panels shall be constructed of 16 SWG sheet steel.

The finishing of the metalwork shall be as specified under Clause 7.

The lids shall be designed and installed to ensure that they can be turned through 90 degrees for easy maintenance. All insulating boards provided shall be of hig quality and adequately supported.

Unless otherwise stated, all distribution boards shall be mounted such that their isolating switches are at least 1500 mm above the floor level.

Distribution feeder pillar
Distribution feeder pillar shall be suitable for outdoor service and weather proof type and be equipped with the number of incoming and outgoing circuits as specified in the drawings. It shall be designed with two lockable, hinged doors and removable back panels and provides easy access to cables and terminations.

The general construction of frame and panel shall be as specified under Clause 5 and 6.

The finishing metal work shall be as specified under Clause 7.

All feeder pillars shall be mounted on plinths, which should be at least 460 mm above the ground. They shall be separately earthed and labeled.

Adequate ventilation, insulating phase barriers for connections, cable boxes, end glands for all the incoming and outgoing ways stated in the drawings (including spare ways) shall be provided for each feeder pillar.

The feeder pillars shall be designed to prevent the entry of water during heavy torrential rain. Unless otherwise stated, barriers of railings shall be provided around each feeder pillar to provide some mechanical protection as necessary.

Busbars
Busbars shall be of hard drawn high conductivity electro-tinned copper conductor with rectangular cross section capable to carry continuously the specified current without overheating. They shall be rigidly mounted on non-hygroscopic insulators to withstand any mechanical forces to which they may be subjected under the maximum fault conditions of 31 MVA. The busbars shall be arranged in a horizontal plane and be painted with red, yellow, blue and black colors at appropriate points to distinguish the phases and neutral. Size of neutral busbar shall be of the same as that of the phases.

An earthing busbar of appropriate cross section shall be run at the base of the switchboard.

Air circuit breakers (ACB)
Air circuit breakers shall be of the air break, metalclad, cubicle, horizontal withdrawable and dead front construction of the specified rating and supplied complete with all the necessary instruments, current transformers, trip fuses, trip devices and protective instruments as called for on the accompanying drawings. The breakers shall be suitable for operating on 415 volts 3 phase, 50 Hz, A.C. system and be certified by A.S.T.A. or KEMA for short circuit breaking and making capacity for 31 MVA or lower in accordance with B.S. 4752. The closing mechanism shall be of toggle action trip free type incorporated with mechanical “ON/OFF” and “ISOLATED/ PLUGGED” indicators shall be fitted with manual solenoid operated closing tripping coils allowing remote closing and tripping as specified.

A mechanical trip pushbutton shall be provided and electrical tripping of the circuit shall be accomplished by A.C. trip coils or if shunt D.C. trip coils are offered, a suitable trickle battery charger and nickel cadmium batteries shall be supplied and installed by the contractor.

All trip units are to be current transformer operated and current transformers shall be of suitable ratio, output type and class of accuracy for their function and shall comply in all respects with BS 3938.

Locking facilities shall be provided so that circuit breakers can be prevented from being opened or closed accidentally by means of padlocks, mechanical and electrical lockouts shall be also be provided to prevent closing of the circuit breaker after an over-current trip.

All circuit breakers shall be tested and set to the requirements of the S.O. by approved and licensed testing contractor. The expenses involved in testing the circuit breakers shall be borne by the contractor.

Busbar coupler
Where ACB is used as a coupler, electrical and mechanical interlocks shall be provided for the two incoming ACBs and the coupler cannot be “close” if both the two incoming ACBs are “close”.

Meters
Meters for the external panel mounting shall be of the flush pattern, with square escutcheon plates finished matt black and pressed steel cases. Indicating instruments shall be to B.S. 89 1-st grade, moving iron spring controlled (M.I.S.C) with 100 mm diameter dials (240 deg. Scale) with external zero adjustment, integrating meters shall be to B.S. 37 Parts 1 and 2 and Part 4 with cyclometric registers and protective relays to B.S. 142.

Voltmeters
Each voltmeters shall be of the M.I.S.C. type, be of suitable voltage range to suit the circuit concerned and of a high degree of accuracy. The voltmeter shall be connected in circuit with a 6-position selector switch and protective cutouts fitted with HRC fuse links.

Ammeter
Every ammeter shall be of the M.I.S.C. type, be of suitable range to suit the current rating of the circuit. It is meant to operate through current transformers. It shall have a high degree of accuracy and be connected to three (3) busbar connected current transformers of the correct ratio, burden and class as stated on the relevant schematic diagram. Unless otherwise specified, ammeter shall also be connected in circuit with a 4 position selector switch.

Power factor indicator
Each power factor indicator shall be of the M.I.S.C. type and be suitable for measurement of 3 phase, 4 wire, unbalanced loads through current transformers (for the voltage coil circuit protection, HRC fuse-links shall be used). The indicator shall be scaled to read from 0.5 capacitive to 1 and from 1 to 0.5 inductive circuits.

Frequency meters
Each frequency meter shall be of moving coil type of range 40 cycles to 60 cycles operating in a frequency sensitive rectifier operated bridge network.

Protection relays
Relays shall confirm to BS 142 and shall be heavy-duty pattern, unaffected by vibration or external magnetic fields and be fully tropicalized.

Relay contacts shall be adequately rated and separate contacts shall be provided for alarms and tripping functions.

Relays shall be provided with phase colored flat indicators, which shall be of the hand-reset pattern and shall be capable of being reset without opening the case. Where two or more elements are included in one case, separate indicators shall be provided for each element.

Relays shall be provided with clearly inscribed labels describing their application and rating. Means shall be provided on the relay panels for testing of protective relays and associated circuits.

Overcurrent and earth fault inverse time protection
Relays shall be of the induction disc/ static, inverse time, overcurrent type. Overcurrent elements shall be supplied with adjustable settings for both operating current and time, the adjustment being possible on load. The range of current setting for phase fault elements shall be 50 to 200 % of rated full load with tapping at 25 % intervals and the time setting adjustment shall be 0 to 3 seconds at 10 times the normal operating current. Inverse time earth fault elements shall comply with the foregoing but shall have a range of settings from 10 to 40 % with tapping at 5 % intervals.

Overcurrent relays shall be of time delay induction disc/ electromagnetic type with adjustable setting of 50 % to 200 % of rated full load and adjustable time device shall open the contacts when overcurrent occurs.

Each leakage relays shall be instantaneous/ induction disc type with adjustable setting of 10 to 40 % and connected to the residual circuit of the current transformers accompanied to each phase which shall open the contacts of the circuit breakers when earth leakage occurs up to the allowable limit as set.

Earth leakage circuit breakers
Earth leakage circuit breakers of direct acting type (ELCB) with a tripping sensitivity of 100/ 300 mA to comply with the requirements of Electricity Supply Board and the National Electric Company shall be provided and installed as shown in the Drawings. Every ELCB shall operate successfully for every earth fault in the installation or circuit it controls even with an open circuit in the incoming neutral conductor.

Current transformers
The current transformer for protection, measuring and metering shall comply with B.S. 3938 and shall be of suitable ratio, output, type and class of accuracy for their function as specified in the Drawings. They shall be able to withstand short circuit rupturing capacity of 35 MVA for 1 second without damage.

The current transformers of the ring type shall have appropriate burdens, classes and ratios to suit the installation. Under no circumstances shall the ratio error at zero burden exceed +1 %.

All current transformers shall be mounted to the fixed position of equipment in such a manner that no pressure shall be exerted on their windings and easy access shall be provided for replacement and maintenance of current transformers.

All current transformers shall carry nameplates, identifying types, ratio, class, output and serial number.

Miniature and moulded case circuit breakers (MCCB and MCB)
The miniature and moulded case circuit breakers shall have the continuous ratings as indicated in the drawings at an ambient temperature of 40 degree C. They shall be suitable for use on a 415/240 volts, 50 Hz, A.C. system and the fault current withstand value shall at least be 5 kA for single phase and 10 kA for three phase units installed ot the distribution boards. For installation at switchboards, it shall withstand a fault current of 43 kA.

The circuit breakers shall be quick-make and quick-break type having center toggle mechanism and shall comply with B.S. 3871 part 1 and 2. All breakers shall have inverse time tripping with thermal magnetic trip elements and adjustments for the MCCBs.

All miniature and moulded case circuit breakers supplied shall be of approved manufacture.

At switchboards where MCCBs are used, there shall be facilities for locking out the toggle switch for maintenance.

Fuse switches
All fuse switches shall be of the indoor, metalclad, cubicle, flush or surface mounted, withdrawable and dead front construction type of the specified not less than those shown in the drawings.

They shall be suitable for operation on 415 volts, 3 phase, 4 wire, 50 Hz, A.C. system and be certified for short circuit breaking and making capacity of 31 MVA in accordance with B.S. 3185 and 861.

The switch contacts shall be of the heavy duty, double air break, slow make and quick break pattern with HRC fuse cartridges bolted onto the moving contacts complete with phase barriers, fully shrouded contacts, hard silver plate switch contacts.

The handles shall be fully interlocked and there shall be positive ON/OFF indication on the bodies of the switches. Interlocks shall be provided to prevent the cover fro being open when the switch is on.

Switchfuses
Switchfuses shall be of the number of poles and current ratings as shown on the drawings and shall be of the totally enclosed pattern, metalclad with positive quick make and quick break action.

Switches shall be capable of passing and also interrupting their full rated current safely and without damage. Switch handles shall be interlocked to prevent opening the cover with the switch “ON”.

Fuse shall be of the HRC cartridge type.

Fuses
All fuses supplied shall be HRC type with rating as indicated on the drawings to B.S. 88 or 1382.

All fuses for switches and feeder pillars shall be ‘Class P’ and ‘Class Q” respectively supplied complete with its appropriate carriers as necessary.

Spare fuses amounting to 20 % of the total requirements shall be provided.

Contactors
Contactors provided shall be constructed and rated in accordance with B.S. 775 and the duty classification shall match the load controlled.

All contactors shall be provided with backup protection either in the form of fuses or circuit breakers for interrupting the fault currents.

All contactors provided shall have easily obtainable parts for repair or replacement.

Starters
Starters to be provided under this contract shall meet with the requirements for Electricity Supply Board’s approval and shall be direct-on-line, star-delta, auto transformer or rotor resistance types as to suit the requirements of motor.

They shall be enclosed in a metalclad cover, be provided with the correctly rated contactors, arc chutes and fault current protection such as trip coils or overcurrent coils.

The starters shall be suitable rated to continuously carry the full load current of the motor and also accept the starting current surges without tripping. In this respect, starters shall be fitted with time delays as necessary to prevent tripping when the motors are started.

Unless otherwise specified, all contactors used shall in the starters shall be constructed for heavy-duty operation.

Starters shall have facilities for manual and remote operation and parts shall be easily obtainable for repair, maintenance or replacement.

Isolators
The isolators supplied shall be of the on-load type with single-pole and neutral, triple pole and neutral and double pole and with the rating as indicated on the drawings. Each unit shall be designed and constructed for heavy duty switching and shall carry the rated current continuously without overheating or damage. “ON” and “OFF” indications shall be provided on the body of the switches. Switch handles shall be interlocked to prevent opening the cover when the switch is “ON”.

Metering panel
The metering panel shall be manufactured from anti-rust zinc coated steel plate of not less than 16 SWG with removable hinged front cover to the electricity supply authority’s requirements. Facilities shall be provided on the panel for mounting of the authority’s meters, cutout fuse units and for wiring connection. Finishing shall be in grey enamel.

Working drawings
Prior to manufacturing of any switchboards, distribution boards and feeder pillars, the contractor shall submit complete working drawings to the S.O.’s reprentative for approval.

Packing
The switchboards, distribution boards and feeder pillars shall be factory assembled and tested before delivery to site and of suitable sizes for installation in the situation as shown on the drawings.

Maintenance
The contractor shall also supply:

a. One set of any special tools, gauges and handling appliances at each switchroom required for the normal maintenance of the standard equipment.
b. Sets, as required, of any special tools, gauge or other test equipment required for the assembly, checking or adjustment (but not for normal maintenance) of the standard equipment.
c. A 915 mm wide and 13 mm thick insulation rubber mat running full length in front of the switchboard
d. One set of “as built” wiring diagram in the main switchroom.

Copyright http://electricalinstallationblog.blogspot.com/ -Electrical switchboard installation

Lighting installation design

This post used to contain a sample need statement for office building lighting design. It was the kind of need statements that are provided to design-and-build contractors or turnkey contractors during the initial stage, when the contractor was invited to submit a proposal.

=== RELATED ARTICLES:

 Hinged louvers for maintenance

===

Photo 1: Recessed lighting

Need statements like this provide a basis to indicate the approximate scope of works and also the standard of installation required by the building owner of the proposed new building.

However, after analyzing the traffic to this blog, I realized that only very few visitors were interested in the content of this post.

When I uploaded the original post, I had an intention to use it as a starter post from which I could link up to more posts and pictures about lighting design and installations.

The sample need statement would not be changed since someone might need it.

Since there seemed to be little interest in the materials, I have made a decision to just use the article of the need statement as an anchor post to link up to pictures and other articles on lighting.

Because of that, the format of the need statement will not be of a need statement any more.

It will be more convenient and faster for me, however, to link up to other posts on lighting in this way.

I have tons of posts to upload to this blogs, but I usually don’t have enough time to write something about it.

I need a method that does not require too much time writing.

So as you scan through this post downward, you will see the links to other posts that contain more photos, diagrams or articles. Follow the link and then come back here for more links.

What I mean is that I will be adding more links to this post in future, using it as an anchor post for lighting designs and installations.

Internal Lighting installation

The illumination levels shall generally be in accordance with the IES Codes, CIBSE Code for Interior Lighting and Lighting Guide 3 (LG3) and the current practices.

As reference, the general installed illumination levels at some of the areas/rooms shall be as follows:

a) Office, reception areas, waiting areas: 300 lux
b) Computer rooms: 500 lux
c) Lecture / Teaching places: 300 lux
d) Circulation areas: 100 lux
e) Electrical / telecommunication switch rooms: 300 lux
f) Areas for rough work: 200 lux
g) Areas for medium work: 400 lux
h) Areas for fine work: 600 lux
i) Internal corridors: 100 lux
j) External corridors: 30 lux
k) Street / compound lighting: 15 lux
l) Multi purpose hall: 500 lux

The lighting systems shall be designed by arrangement of alternating circuits, proper grouping of lighting switches, separate switching etc. so that unnecessary light fittings can be switched off as desired.

Thus the concept of energy saving shall be considered in the lighting system design.

The luminaries shall generally be of the following types:

1. Air-conditioned areas – Recessed fluorescent fittings with full aluminum parabolic reflectors and louvers complete with hinge for easy maintenance or whichever is appropriate.

2. Non air conditioned areas – Recessed fluorescent or surface mounted fluorescent fittings with full aluminium parabolic reflectors and louvers complete with hinge for easy maintenance.

3. Computer / data processing rooms – Recessed fluorescent fittings with full aluminium parabolic reflectors and louvers complying with CIBSE LG3 or Cat. 2 whichever is appropriate, complete with hinge for easy maintenance.

4. Corridors – Suitable types of recessed or surface mounted fluorescent fittings with full aluminium parabolic reflectors and louvers complete with hinge for easy maintenance, OR suitable type of recessed or surface mounted down lighter with energy saving discharge lamp, whichever is appropriate.

(Links: Hinged louvers for maintenance)

5. Store rooms / toilets – Suitable types of fluorescent fittings, OR suitable types of recessed down light with energy saving discharge lamp.

6. Meeting rooms / conference rooms – Same as office areas but supplemented by PAR down lights c/w dimmer.

7. Plant rooms – Suitable types of fluorescent fittings.

8. Other areas – Suitable types of light fittings.

9. Multi purpose halls – Suitable types of light fittings supplemented by PAR down lights c/w dimmers.

10. Walk path, garden and parks – Suitable types of foot path lantern c/w miniature PL/SL lamp with suitable height, controlled by time switch and/or photo-sensitive sensors whichever is appropriate.

11. Street / compound – Suitable type post with top or side entry SON fitting mounted on/in galvanized/ aluminium/ fiberglass/ composite die cast/ concrete R.C. poles of suitable height controlled by time switch and/ of photo-sensitive switch whichever is appropriate.

Luminaires for special requirements and areas:

1. Gallery/ exhibition/ showcase areas – Suitable decorative fitting, track lighting c/w ultraviolet filters to protect the exhibition materials.


Exit lights and self contained emergency lights of fluorescent type with three hours battery reserve shall be provided for all areas in accordance with the requirements of the Fire Department.

Suitable self contained emergency lights with sufficient lighting level for normal operation and with minimum three hours battery reserve shall be installed in staircases, public areas, electrical/ telecommunication switch rooms, riser rooms/ areas and other rooms/ areas in accordance with the requirements of the Fire Department.

Fluorescent tubes installed shall be of deluxe type with color temperature of approximately 4000 degrees K similar to Philips code 84. External street lighting, compound lighting and flood light shall be of SON type.

Lighting for walk paths shall be of miniature fluorescent lamps such as PL lamps. Ballast loss for fluorescent fitting and compact fluorescent / down lights shall be 6W loss. Insect fittings shall be installed at kitchen, cafeteria and other area as specified by Project Director/ Project Director Representative.

The common corridor, public areas etc. shall have two levels of illuminance (evening/ night) such that after midnight the lighting cab be reduced to a lower level.

The switching of these lights shall be by automatic time switches complete with 24 hours battery reserve and manual override or by other appropriate methods.

Depending on the functions of the department/ areas, some of the light fittings shall be connected to the essential circuits.

Suitable and adequate number of outdoor lighting with SON/ Metal Halide shall be provided for games courts such as badminton courts, squash courts, volley ball courts, etc.

External Lighting Installation

All works shall comply with the requirements, rules and regulations. They shall also follow the relevant latest circular for external lighting.

External lighting installations shall consists of Street Lighting, Compound Lighting, Garden/ Landscape Lighting, Sport Lighting, Area Floodlighting, Security Lighting, Fence Lighting, Façade Lighting, etc.

Compound/ street lighting shall be provided for the compound and internal roads within the compound of the project. The compound/ street lighting shall be mounted on galvanized/ aluminium/ fiber glass/ composite die cast poles/ concrete R.C. poles not exceeding 3.0 meters in height for compound lighting and 8.0 meters for street lighting. Wall mounted light fittings shall be used where pole mounted light fittings are not suitable.

Generally, the spacing between the poles shall not exceed three times the mounting height of the pole. The lamps for the light fittings of SON type. The illumination level on the ground/ road surface shall not be less than 1.5 lumens.

Suitable path lighting with PL lamps shall be provided in the parks and gardens and at the walk paths.

Suitable lightings shall be provided for guardhouse, signage, front fencing, etc.

Area floodlight shall be provided where necessary.

Suitable lighting with SON/ Metal Halide lamps shall be provided for games courts such as tennis court, badminton courts, volley ball courts, etc. The light fittings shall be on hot dipped galvanized steel poles/ concrete R.C. poles with climbing rungs and easy maintenance, etc.

All external compound/ street/ flood/ path lightings shall be provided with time switches and manual bypass or by other appropriate methods for automatic and manual switching. The lighting systems shall be of such design so that after midnight the lighting levels can be reduced if required.

Façade lighting consisting of floodlights, directional lights, etc. shall be provided to enhance the façade of the buildings.

Copyright http://electricalinstallationblog.blogspot.com/ - Lighting installation design

Electrical maintenance manual

The following provides sample specifications on operation and maintenance manual that can be used in an electrical installation contract for a multi-storey office building.

GUIDELINES FOR OPERATION AND MAINTENANCE MANUAL FOR MECHANICAL AND ELECTRICAL EQUIPMENT.

All operation and maintenance manuals for Mechanical and Electrical equipments shall follow the guidelines as setout below. These guide-line are means exhaustive and shall in no way absolve the responsibility of the Contractor to provide a complete and informative operation and maintenance manual. 
The operation and maintenance manual shall comprise the followings:

1. GENERAL DESCRIPTION
a. Introduction
i. Brief description of the system.
ii. List of Equipment installed.
b. Plant layout and area classification.
Block diagram of the system indicating major equipment and location.
c. Design criteria, codes and standards where appropriate.
d. Names, telephone nos and addresses of persons to contact in case of emergency repairs/breakdown.

2. FEATURES OF THE SYSTEM
a. Highlight all the important features of the system.
b. Highlight all the necessary features that operator should know before operating the plant.
c. Explain all the indication meters and stated the safe operating limits which the meter should show for correct operation of the equipment.


3. BASIC OPERATION
 Step by step operation instructions.


4. PREVENTIVE MAINTENANCE
a. Preventive maintenance routines to be carried out by in house maintenance team.
b. Preventive maintenance routines to carried out by the specialist contractor.
c. Equipment manufacturer’s recommended preventive maintenance.
d. Check-list for parts to be serviced and/or replaced at 3 months interval.

5. SIMPLE DIAGNOSTIC PROCEDURES
a. Simple trouble shooting procedures to be carried out by the in house maintenance team before requesting service from the specialist contractor.
b. A complete list of DO’s and DON’Ts for the in house operation and maintenance staff.

6. TEST DATA AND CERTIFICATION
a. Performance Testing data sheets.
b. Certifications from the suppliers/manufacturer or representative from the supplier/manufacturer to confirm the installation complies with the supplier/manufacturer’s recommendations and all the conditions stipulated in the warranty by the supplier/manufacturer the installation.


7. TECHNICAL SPECIFICATIONS
Providing complete technical specifications of every equipment installation comprising the followings:
a. Serial Nos.
b. Name Plate details.
c. Capacities. (Maximum Rated at Design Conditions.)
d. All technical data as per contract document/equipment manufacturer’s brouchers.

8. MANUFACTURER’S BROCHURES
Equipment manufacturers’ published brochures, catalogues and leaflets highlighting the data of the equipment installed with ‘STABILO BOSS” fluorescent marker system.  

9. AS-BUILT DRAWINGS
 Updated and emended shop-showings indicating the actual installation.
 
Copyright http://electricalinstallationblog.blogspot.com/ - Electrical operation and maintenance manual

Surge installation

The following provides sample specifications that can be used in a lightning surge suppressor installation contract for a multi-storey office building.
 
1.0 GENERAL

1.1 This document describes the tender specification requirement of lightning and surge protection system for essential and critical equipment installed as per design drawing. Heavy duty industrial grade type of lightning surge protection system is essential to prevent equipment from damage, degradation of components or parts as well as down time resulting from system disruption.  

1.2 In view of the above, the superintending officer / consultant shall fully ensure and authorize that the protection system offered, strictly comply or fulfill the technical specification requirement.

1.3 The tenderer shall be required to submit catalogue and a schedule for the lightning and surge suppressor system indicating the type of installed suppressor and location to the consultant for approval. The tenderer is also required to provide upon request warranty certificates from the manufacturer or distributor. The consultant shall reserve the right to inspect the lightning and surge suppressor system at site.


2.0 TECHNICAL BACKUP, ENGINEERING SUPPORT AND TRACK RECORD

2.1 The supplier/local agent of the protection equipment shall be able to provide full technical and continuous engineering support in the event of any lightning/surge/power problems. As such it is mandatory that the local agent must have at least 10 years proven experience in the lightning and surge protection field or hold an agency/representation in lightning surge products for at least 10 years.

2.2 It also important that they must have qualified engineers, trained technician and appropriate laboratory to ensure that their products are compatibly matched with the power supply safety requirements, testing quality assurance certification and good & proven track record in tropical condition.


3.0 WARRANTY

3.1 As part of contract requirements, the local authorized agent must provide pre and post local authorized warranty or certification. As such, only genuine products with a local authorized distributor will be considered and all products offered must be provided with country of origin certification for originality marking and minimum 5 years spare part support. A letter of support from the manufacturer shall be submitted.

3.2 A warranty certificate shall be obtained from the local authorized agent stating clearly a full 2 year warranty against in both materials and workmanship defect.

3.3 A service warranty shall available for service and maintenance based on 6 months duration after handling over upon requested.


4.0 STANDARDS

4.1 All stages of equipment shall comply with the specifications. The suppressor units shall be tested in accordance to ANSI/IEEE C62.41, IEEE 587, VDE 0675, and IEC 61024-1/IEC 61312-1.

4.2 In meeting with Malaysia safety standards, the lightning surge protection devices shall also be tested by international laboratories that are recognized by the Electrical & Electronics Association of Malaysia and Energy Commission, JBEG.



5.0 ON-SITE TECHNICAL SUPPORT

5.1 Upon installation, the supplier/local agent shall be able to provide an on-site testing & commissioning to check the status of the installed suppressor units. The respective suppressor modules shall be checked using a dedicated suppressor tester where applicable, including visual inspection of suppressor type, location, etc...

5.2 In event of extreme lightning and surge discharges, a suppressor unit often sacrifices itself in protecting the equipment. An optional on-site warranty must be provided to monitor the condition of the suppressor units at regular intervals (not longer than 6 months). The respective suppressor modules shall be checked using a dedicated suppressor tester where applicable including visual inspection of the flag status.



6.0 PROTECTION REQUIREMENT

 The protection system shall comprise of the following:-

6.1 Low Voltage (L.V.) System 

1. Lightning Horn Surge Suppressor (LHSS-MDB)
(Cat 1 protection at MSB/EMSB)

2. Fine Surge Suppressor - Duplex (FSS-D/AG)  
(Cat 2 protection at Genset AMF board)

3. Combined Lightning Surge Suppressor (CLSS)  
  (Cat 1&2 protection at Remote Building)

4. Fine Surge Suppressor (FSS-AG)
(Cat 2 protection at DB SSB)

5. Series Surge Suppressor (SSS)  
(Cat 3 protection at incoming power for Critical/Sensitive Equipments)




 6.2 Extra Low Voltage (E.L.V.) System

1. Telephony Surge Suppressor (TSS)
  (Cat 4 protection for Telephony cables)

2. CXSS – Coaxial Surge Suppressor
  (Cat 4 protection for MATV antenna cables)

3. DSS – Data-line Surge Suppressor
  (Cat 4 protection for data/signal line cables)


6.3 Reliability of Equipment System

The Lighting Surge Protection Equipment shall be able to operate continuously up to maximum voltage of 275V per phase suitable with local electricity supply voltage variation.
   

6.4 Experience and Track Record

The products / protection devices offered shall have a proven track record of implementation / installation in projects of similar nature. Domestic or commercial type of products are not acceptable for critical application projects.


6.5 Factory Acceptance Test

In the event of schedule Factory Acceptance Test, the Lightning Surge Protection Equipment shall be fully integrated during the test of overall L.V. or E.L.V. system.
 






















7.0 LOW VOLTAGE PROTECTION-CAT 1 AT MSB/EMSB 

  LIGHTNING HORN SURGE SUPPRESSOR-MDB (LHSS-MDB)
   

7.1 The Lightning Horn Surge Suppressor (LHSS-MDB) shall be a heavy-duty electronic controlled surface arrester unit utilizing the arc chopping principle to limit and discharge lightning surges. 

7.2 The Lightning Horn Surge Suppressor (LHSS-MDB) unit shall be a single channel modular type mountable on standard DIN rails and of non-fusible elements capable of limiting surge voltages from indirect and direct lightning strikes and have a long service life.

7.3 The Lightning Horn Surge Suppressor (LHSS-MDB) unit shall be tested to withstand up to 50kA of 10/350us lightning waveform in accordance to latest revision of IEC 61024-1 and IEC 61312 standards.

7.4 The lightning gap unit (neutral to earth) shall also be tested to withstand up to 100kA of 10/350us lightning waveform and rated at 260V.

7.5 The LHSS-MDB unit shall conform to the following specifications:-

 1. Nominal rated voltage - 240V AC per phase
 2. Continuous rated voltage - 335V AC per phase
 3. Maximum lightning current (as per IEC):
 a. Phase Lightning suppressor  
  10/350us waveform - 50 kA per phase
 b. Net follow current
  self extinguishing at 400VAC - 50 kA
 4. Neutral - Earth Lightning gap
  10/350ms waveform - 100 kA
  5. Voltage limitation at Max. lightning
  current (50kA, 10/350ms) - < 900 V
  6. Rated voltage - Lightning Gap - up to 260V
  7. Response Time - < 1 us
  8. Surface discharge arrester - Electronic Arc 
  Chopping Gap 
 9. Connection - ‘3 + 1’ configuration  
  suitable for TT-system.
10. Suppressor fuse - Non-welding type
11. Lightning Surge Monitoring (Optional)
  a. Continuous line voltage monitoring - Yes
  b. 8 mode suppressor fuse monitoring - Yes
  c. Output signal for remote monitoring - Yes
  d. Audible alarm signal - Yes (Optional)








8.0 LOW VOLTAGE PROTECTION-CAT 2 AT GENSET AMF BOARD

FINE SURGE SUPPRESSOR/DUPLEX (FSS-D/AG)

8.1 The Fine Surge Suppressor/Duplex (FSS-D/AG) unit shall be a rail mountable, modular two-piece construction type with base element and a protection plug suppressor suitable for protection of distribution boards and its loads. 

8.2 The protection plug shall be equipped with a flag to indicate the status of the components and a remote warning contact shall also be integrated in the suppressor unit to act as a remote warning switch in the event of suppressor failure. 

8.3 The Fine Surge Suppressor/Duplex (FSS-D/AG) unit shall be suitable for TT-system and configured to match installation option before and after Earth Fault device.

8.4 The FSS-D/AG unit shall conform to the following specifications:-
  
 1. Phase to Neutral Fine Suppressor
  a. Rated nominal voltage - 240V
  b. Continuous rated voltage - 275V
  c. Voltage limit at 5kA,8/20ms - < 1kV
  d. Voltage limit at 20kA,8/20ms - < 1.35kV
  e. Rated surge current - 40kA
  2. Neutral to Earth Fine Suppressor
  a. Rated voltage - 260V
  b. Voltage limit at 5kA,8/20ms - < 150V
  c. Voltage limit at 20kA,8/20ms - < 1kV
  d. Rated surge current - 40kA
  3. Phase to Phase Fine Suppressor
a. Rated voltage - 600V
b. Rated surge current - 30kA
4. Connection - ‘3 + 1’ configuration  
  suitable for TT-system
5. Suppressor fuse - Non-welding type
6. Suppressor Monitoring - 7 modules cum with 14
  mode remote signaling. 
















9.0 LOW VOLTAGE PROTECTION-CAT 1 & 2 AT REMOTE BUILDING

COMBINED LIGHTNING SURGE SUPPRESSOR - CLSS


9.1 The combined lightning surge suppressor (CLSS) shall consist of combined lightning and surge protection modules, which are fully coordinated via active energy control to provide maximum protection against lightning and surges at LV service entrances and remote power units.

9.2 The lightning element of the combined lightning surge suppressor (CLSS) unit shall be electronically controlled and of heavy duty and non-degradable construction. It shall be configured based on multistage protection elements and suitable for TT network.

9.3 The lightning element of the combined lightning surge suppressor (CLSS) unit shall be a single channel modular type mountable on standard DIN rails and of non-fusible elements capable of limiting surge voltages from indirect and direct lightning strikes and have a long service life.

9.4 The surge element unit shall be a rail mountable, modular two-piece construction type with base element and a protection plug suppressor. 

9.5 The surge protection plug shall be equipped with a flag to indicate the status of the components and a remote warning contact shall also be integrated in the suppressor unit to act as a remote warning switch in the event of suppressor failure. 

9.6 The CLSS unit shall be specified to provide sufficient protection level and it shall conform to the following specification.

1. Nominal rated voltage: - 240V AC
2. Total Lightning Current Exposure: - >200kA of 10/350 us wave
3. Surge Rating per phase - 40kA of 8/20 us wave
4. Lightning Gap Rating per phase - 100kA of 10/350 us wave
5. Protection level on 10/350us - <900V
6. Connection - ‘3 + 1’ configuration  
  suitable for TT-system
7. Suppressor fuse - Non-welding type
8. Surge Suppressor Monitoring - Individual double-mode remote signaling. 












10.0 LOW VOLTAGE PROTECTION – CAT 2 AT DB SSB

  FINE SURGE SUPPRESSOR (FSS-AG)

10.1 The Fine Surge Suppressor (FSS-AG) unit shall be a rail mountable, modular two-piece construction type with base element and a protection plug suppressor suitable for protection of distribution boards and its loads. 

10.2 The protection plug shall be equipped with a flag to indicate the status of the components and a remote warning contact shall also be integrated in the suppressor unit to act as a remote warning switch in the event of suppressor failure. 

10.3 The Fine Surge Suppressor (FSS-AG) unit shall be suitable for TT-system and configured to match installation option before and after Earth Fault device.

10.4 The FSS-AG unit shall be specified to provide sufficient protection level and it shall conform to the following specification.
  
 1. Phase to Neutral Fine Suppressor
  a. Rated nominal voltage - 240V
  b. Continuous rated voltage - 275V
  b. Voltage limit at 5kA,8/20ms - < 1kV
  c. Voltage limit at 20kA,8/20ms - < 1.35kV
  d. Rated surge current - 40kA
  2. Neutral to Earth Fine Suppressor
  a. Rated voltage - 260V
  b. Voltage limit at 5kA,8/20ms - < 150V
  c. Voltage limit at 20kA,8/20ms - < 1kV
  d. Rated surge current - 40kA
3. Connection - ‘3 + 1’ configuration  
  suitable for TT-system
4. Suppressor fuse - Non-welding type
5. Suppressor monitoring - 4 modules cum with 8
  mode remote signaling
6. Intelligent remote signal/monitoring - Optional audio alarm & 
  over voltage limiter 
  disconnection signal.  













11.0 LOW VOLATEGE PROTECTION – CAT 3 AT INCOMING CRITICAL/SENSITIVE EQUIPMENT

SERIES SURGE SUPPRESSOR (SSS)
 Series Type Multistage Surge Suppression System 

11.1 The series suppressor shall employ the Transient Tracking Technology multistage and multi-level suppression system to provide full time protection of the incoming power to sensitive equipment.

11.2 The main stage of the series suppressor shall be operated in a series connection with transient tracking control technologies for intelligent tracking and suppression for transients, spikes and noise along the sine wave.
11.3 Instant absorption and suppression of the transients shall be provided by a combination system of reliable series and shunt surge absorption components utilizing the high energy transient tracking control module.

11.4 It shall also be equipped with an output stage for bi-directional protection against internally generated transient and with an overall lower let through voltages.

11.5 EMI and RFI noise rejection modules can be incorporated into the three phase series suppressor system for units above 100A as per specification requirements or drawings.

11.6 The Series Surge Suppressor (SSS) shall have a total withstand capability in accordance with ANSI/IEEE C62.41 and complying with the following specifications:-

 1. Response time - < 25 ns 
  2. Operating frequency - 50 - 60 Hz
  3. Surge Attenuation - 40 dB / 60 dB  
  4. Bandwidth protection - 10kHz – 50Mhz
  5. Surge exposure/ phase - 40kA, Maximum up to 140kA
  6. Surge suppression system - Multistage & multilevel series, 
  in-corporate Transient 
  Tracking Technology
  7. Performance - Bi-directional protection
  8. Manufacturing standards - AS 3000
  9. Construction - Metal clad or polycarbonate
  enclosure  
  10.Overload safety protection - 5 x rated capacity for 1 sec.
  11.Temperature Range - -40 to 60 deg C
  12.Indicator Status - Yes
  13.Power Meter (Optional) - Yes
  14.Remote Monitoring Interphase - Yes
  15.Bypass Feature (Optional) - Yes

11.7 The series surge suppressor (SSS) shall be suitably configured to
ensure that it operates effective with upstream Level 1 and Level 2 systems. The supplier shall / may be required to provide documentation / tests to prove that the various levels of protection are properly matched and compatible.

12.0 E.L.V SURGE PROTECTION - CAT 4 FOR TELEPHONY CABLES

 TELEPHONY SURGE SUPPRESSOR (TSS)

12.1 The telephony surge suppressors (TSS) shall provide protection against line transients or over-voltages on all incoming STM as well as PABX incoming and outgoing extension lines as per specification drawing requirement. 

12.2 They shall be of plug-in modular to telephone MDF Krone system and these plug-in modules shall permit on site repair without rewiring required.

12.3 The TSS units shall able to handle surge withstand capability of up to 10 kA with arresting time of less than 1 hs matches with the equipment criteria to suit its applications, such as frequency, operating voltage, impedance etc. 

12.4 The TSS unit shall be complying with the following specification.

1. Protection pair - single pair protection per module
2. Maximum line voltage - 170 VDC
3. Protection level - 220 VDC tested at 5kA, 8/20us
4. Rated surge capacity - 10kA, 8/20us
5. Response time - <1 ns
6. Protection circuit - Multi stage MBB type
7. End of life - Short circuit



























13.0 E.L.V PROTECTION - CAT 4 FOR COAXIAL CABLES


 COAXIAL SURGE SUPPRESSOR (CXSS)
  - For MATV Antenna Receiver Application

13.1 The coaxial surge suppressor shall be designed to provide protection against over voltage during lightning and electrical transients in the coaxial cables for MATV antenna systems.

13.2 It shall be suitable for protection of antenna system without introducing a large insertion loss into the system.

13.3 The coaxial surge suppressor shall have a surge withstand capability of 10kA and be fully operational up to frequencies of at least maximum up to 300MHz. It shall incorporate a sleek design with a wide range of connectors for easy and quick installation.

13.4 The CXSS unit shall be complying with the following specification;

1. Rated surge capacity - 10 kA (8/20us)
2. Frequency Range - up to 300 MHz
3. Insertion Loss at 300 MHz - < 0.5 dB 
4. Insulation Resistance - > 1 GW
5. Residual Voltage - < 600 V (1kV/us)
 6. Impedance - up to 75 ohms
 7. Connection - suitable to equipment
 8. Construction - Solid state in die cast aluminum



























14.0 E.L.V PROTECTION - CAT 4 FOR SIGNAL COMMUNICATION CABLES


 DATA-LINE SURGE SUPPRESSOR (DSS)
- For data lines, control signal lines and communications circuits 
  application.

14.1 The DSS unit shall provide protection against line transients or over-voltages sensitive and critical datalines, control signal and communications circuit as specified in drawings. 

14.2 They shall be a series in-line protection type which shunt or parallel type of protectors are not acceptable. 

14.3 The DSS units shall able to handle surge withstand capability of up to 10 kA with arresting time of less than 1ns matches with the equipment criteria to suit its applications, such as frequency, operating voltage, impedance etc. 

14.4 The DSS units shall be of multi level protection designed and din-rail mounting construction and bi-directional protection system shall be provided as per design requirements.
 
14.5 The DSS units shall be complying with the following specification;

1. Rated surge capacity - 10 kA (8/20us)
2. Range of voltage - from 6 VDC to 170 VDC
3. Response time - < 1 ns
4. Maximum line current - up to 500mA
5. Construction - Din-rail mounted


Copyright http://electricalinstallationblog.blogspot.com/ - Lightning surge protection installation

Electrical conduit installation

The following sample specifications covers the use of rigid and flexible metal and PVC conduit installation for an electrical wiring work contract in a new multi-storey office building.
Scope
The scope of this section is to set out the requirements, methods, materials, workmanship, standards and regulations in connection with the electrical equipment and their installation works for this project.
General
These specifications shall be read together with the relevant drawings, and schedule of quantities if there is any, that form part of this contract. All the works of wiring and cabling are generally as indicated and specified on these drawings.

Ducts and trenches necessary to accommodate cables and switchgears that are generally shown on the drawings will be provided by Contractor unless otherwise stated. However, it shall be the contractor’s responsibility to ensure during the progress of the work that the various ducts and trenches are constructed in the correct manner and that they are adequate for the electrical works whether such details are specifically mentioned or not.
Wiring methods
All wiring shall be of the “loop-in” system and no joint shall be accepted except at the terminations of the electrical accessories and/or equipment. No reduction in the number of strands of cables shall be allowed at the terminals. All strands shall be effectively terminated and secured by screws, nuts and washers or other approved means of fixing.
Concealed wiring
All wiring to be concealed shall be neatly run in the concrete or plaster. They shall be secured firmly to the surfaces on which they run by means of lead saddles at interval of not more than 600 mm.

There shall be a plaster cover of at least 12 mm over all such concealed wires. It is imperative that all the wiring is completed before surfaces are plastered.

Cables shall be concealed behind cement plaster in the walls and/or ceilings or concealed in roof spaces behind false ceilings. Where cables run over surfaces other than wood behind ceiling, they must be protected by conduit. Chases, not deeper or wider than is necessary to accommodate the cable runs, shall be cut in the concrete/brick walls and ceilings. The cables when fitted shall not protrude beyond the surface of the walls and ceilings. Final rendering and plastering shall be carried out by the Contractor. Cable runs shall always be parallel or perpendicular to walls and shall be adequately secured by non-rusty wiring clips and brass nails at appropriate intervals. Any cutting and chipping of concrete shall be approved by S.O.

Electrical accessories where possible shall be flush fitting housed in open metal or aluminum boxes of appropriate thickness sunk into the walls and fastened by rawl plugs and brass screw. The open side of the metal box shall flush with the plaster wall surface and a hole shall be drilled at the back to permit cable entry.

Accessories which cannot be fitted flush with wall surface shall be mounted on hard wood blocks of suitable size and thickness which shall be fixed to the walls by means of rawl plugs and brass screws so that the surface of each block shall finish flush with the plastered wall surface.
Surface wiring
Cables shall run on the surface of walls and ceilings or in the roof of spaces and secured by lead alloy saddles of approved design. Saddles shall be fixed by brass nails or screws spaced and not more than 150mm apart and not more than 10 cables shall be clipped together using the same saddles.

Where cables run over surfaces other than wood, they must be secured on treated hardwood battens firmly fixed in position with rawl plugs and brass screws. Cable run shall always be parallel or perpendicular to walls and earth wires shall be fixed on the outside of the cable runs. All wiring which is installed at less than 1200 mm above floor level or subject to mechanical damage easily shall be protected with a wooden or plastic casing.

Electrical accessories shall be of the surface pattern type fixed on hardwood blocks with brass screws. Where more than one piece of accessory are grouped together, a single wooden block shall be used to accommodate all the accessories. However, it shall not be larger than necessary and it shall be cut at the side of the wooden block to permit cable entry.
PVC insulated cable
PVC insulated cables shall mean Polyvinyl chloride insulated cables. The conductors shall be of high conductivity stranded copper conductors. They shall manufactured in accordance with the specifications of BS 6004 or MS 136 and be of the 600/1000 volts grade.

The colors of the insulation shall be in accordance with Table 51A of the 16th Edition of IEE Wiring Regulations.

Cables to be used for surface and concealed wiring shall be PVC insulated and PVC sheath. All cables shall be supplied at maximum required lengths and no joints are permitted.
Conduit installation
All conduits, fittings and associated accessories shall be galvanized and shall comply with B.S. 31. Conduits shall be screwed and welded Class “B” and fittings shall be manufactured from steel or malleable cast iron.

Where PVC conduits are specified, they shall be of high quality rigid type with all approved type joints, tee off and jointing materials.

Concealed conduit shall be fixed securely to prevent movement before casting of floor slabs, floating of plaster and casting of columns and beams.

Conduits and associated accessories shall be painted with one coat of red lead whenever the exposed galvanized surface has been cut or otherwise damaged including exposed threads and connections after erection.

Conduits shall be properly and tightly screwed into the full depth of box spouts and butted in sockets between lengths to ensure maximum mechanical strength and electrical continuity so that the wiring is continuously and effectively protected throughout its whole length, is not in anyway under mechanical stress.

The whole of the conduit system shall be continuous throughout. A separate earth continuity conductor shall be provided in all metal conduits. All conduits shall be earthed at terminations.

Flexible metal conduits shall not be accepted as a means of providing earth continuity. A separate earth continuity-conductor shall be provided with every part of the system formed by such conduit.

Conduit sizes shall be selected carefully for the number and size of cables they are to contain. The conduits shall be arranged with an adequate number of boxes to allow easy draw in and draw out of any one or all of the cables at any time.

The conduit sizes shall not in any circumstances be less than 20mm and the number of cables drawn in shall not be greater than the appropriate number permitted in the 16th Edition of IEE Wiring Regulations.

Cables for lighting and power circuits shall not be drawn into the same conduit as those for extra low voltage systems.

Lighting and power final circuits shall not be run in the same conduits, except where an adaptable box is employed as a final distribution point. A number of final circuits may be grouped together in a larger circuit between the distribution board and the adaptable box provided that all sub-circuits are of the same phase.

In case of three phase circuits, all three phases and neutral if any should be drawn into the same conduit. Where condensation is likely to occur in surface conduits they shall be laid in falls to drain off condensed moisture so it does not gain entry into terminations.

Conduit work and accessories where not concealed shall be fixed effectively by means of heavy patterned spacing saddle and some approved metal or other non-disintegrating plugs of proprietary manufacture.

On straight runs the conduit shall be supported by saddles at intervals not exceeding 900 mm in addition to supports provided by any structure, box or fittings included in the run. For 40 mm conduit saddles maybe spaced at intervals not more than 1220 mm.

Hanging or suspending conduits using wires are not permitted.

Bends must in all cases be supported on each side by two saddles as near thereto as possible and a draw in box shall be provided after two bends and after not more than each 9 m of straight run.(See photo: Distance between conduit draw box )

Where conduits cross expansion joints they shall be installed in such a way so as not to resist relative movement of the sections. A suitable crossing shall comprise conduits telescoped one inside the other with the free ends or ends projecting immediately to one side of the crossing. Earth bonding of the telescoped end, which shall be suitable bushed, shall be affected inside the box to maintain earth continuity of the system.

Immediately on the completion of erection of any conduit during building construction all exposed switch, socket and conduit risers shall be plugged effectively against the ingress of water and dirt particularly where concrete shall be poured. Such seals shall be maintained in good order for such times as is necessary to complete wiring and connection of fittings and switches.

All conduits shall be swanned out and free from moisture to the S.O. satisfaction before wiring is commenced. Draw in tapes with absorbent cloth, such as flannel or army pull through cloth shall be used for this purpose.

On completion of the installation all exposed conduits shall be painted with two coats of good quality approved paint and to the satisfaction of the S.O.
Cable trunking installation
Cable trunking may be employed in lieu of conduit where multiple runs would otherwise occur.

All cable trunking shall be manufactured from good quality hot dipped galvanized mild sheet steel of not less than 18 SWG for sizes up to 100mm x 100mm and not less than 16 SWG for sizes up to 150mm x 150mm and not less than 14 SWG for larger sizes.

The trunking shall be installed complete with all necessary accessories such as bolted flanged outlets, blank ends, reducers, outlet bushes, bends, tees, sleeve couplings, intersection four way boxes and fitting adapters.

Bridge pieces to act as cable retainers shall be readily removable, but positive fixing by machine screws for cover shall be provided. The inner radius of any bend shall not be less than 2.5 times the minor dimension of rectangular section trunking.

A 25mm x 3 mm copper tape shall run throughout the whole length of trunking from main switchboards to sub-switchboards, from main switchboards to distribution boards and from sub-switchboards to distribution boards to provide earth continuity. All trunking shall be supported adequately by suitable brackets fabricated from galvanized mild steel sheet flat.

Whenever permitted by the S.O., cables for power and lighting circuits and extra low voltage systems shall not be run in the same trunking unless they are segregated effectively by means of rigidly fixed metal barrier or screen.

The erection work of a trunking must be completed before any cable is drawn in.

The number of cables run in a trunking shall be such that a minimum space factor of 45 percent is provided.
Cable tray installation
Perforated hot dipped galvanized mild steel cable trays of not less than 16 SWG may be employed in lieu of conduit.

Trays shall be of appropriate width with an up-turned flange both sides 20 mm deep and shall be with all necessary long radius bends and tees and fixing brackets fabricated from mild steel flat.

They shall generally be supported by directly beaming into top side of the concrete rib construction at 1820 mm centers forming the ceiling and in this event only, a simple and efficient approved clamping arrangement to the ribs shall be affected to prevent lateral displacement of the tray.

Trays may be employed in other situations at the discretion of the contractor in order to carry out multiple runs of the M.I.C.C. and multi core cables as an alternative to fixing by saddles to the structure.

If trunking or cable trays are used in lieu of conduits, care shall be taken to ensure that all trunking, cable trays and cable runs in areas known to contain corrosive vapors are painted with an approved type of anti-corrosive paint and it shall be deemed that the cost of such painting has been included in the contract sum.

A 25 mm x 3 mm copper tape shall run throughout the whole length of the cable tray to provide earth continuity.
Ducts and trenches
Unless otherwise stated, ducts and trenches necessary to accommodate cables and equipment will be provided by the building Contractor in accordance with the drawings. However, it shall be the Contractor’s responsibility to ensure during the progress of work that the various ducts and trenches are constructed in positions as are required by the electrical distribution works and as such, are adequate for these requirements whether specifically mentioned herein or not.

If these ducts are not provided the contractor must advise the S.O.’s as soon as possible.

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