SECTION 26 05 33-ELECTRICAL RACEWAYS.pdf

MINISTRY OF HOUSING Western Sector Projects Sitework & Infrastructure OMRANIA and ASSOCIATES Project Specification

ELECTRICAL RACEWAYS SECTION 26 05 33 - 1

SECTION 26 05 33

ELECTRICAL RACEWAYS

PART 1: GENERAL

1.01 SECTION INCLUDES

A Electrical raceways and accessories including, but not limited to the following:

1. PVC conduits.

2. Electrical metallic tubing (EMT).

3. Rigid steel conduits.

4. Flexible conduits.

5. Metal Cable trunking.

6. Cable trays.

7. Cable ladders.

1.02 RELATED SECTIONS

A Section 01 31 00 Project Management and Coordination.

B Section 0133 00 Submittals Procedures.

C Section 01 61 00 Common Product Requirements.

D Section 01 78 36 Warranties.

E Section 26 05 00 Common Work Results for Electrical.

F Section 26 05 53 Electrical Identification.

G Section 26 05 13 MV Cables and Accessories.

H Section 26 05 19 LV Cables and Wires.

I Section 260533.13 Electrical Boxes and Fittings.

J Section 26 05 29 Equipment Connections and Supports.

K Section 33 71 19 Underground Electrical Services.

1.03 REFERENCES

A SASO Saudi Arabian Standards Organization.

B IEC 60364 Electrical Installations of Buildings.



C BSEN 1991 Euro-code 1, Actions on Structures.

D BSEN ISO 2081 Metallic and other Inorganic Coatings, Electro-plated Coatings of Zinc with Supplementary Treatments on Iron & Steel.

E BSEN ISO 4526 Metallic Coatings, Electroplated Coatings of Nickel for Engineering

Purposes.

F BSEN 10143 Continuously Hot-Dip Coated Steel Sheet and Strip.

G BSEN 10346 Continuously Hot-Dip Coated Steel Flat Products.

H BSEN 12020-2 Aluminium and Aluminium Alloys, Extruded Precisions Profiles.

I BSEN 12844 Zinc and Zinc Alloys, Castings Specifications. J BSEN 60423 Conduit Systems for Cable Management. K BSEN 61386 Conduit Systems for Cable Management.

L BS 476 Fire Tests on Building Materials and Structures.

M BS 4568 Specification for Steel Conduit and Fittings with Metric Threads of

ISO form for Electrical Installations.

N BS 4607 Non-Metallic Conduits and Fittings for Electrical Installations. O BS 4662 Boxes for Flush Mounting of Electrical Accessories. P BS 7671 Requirements for Electrical Installations (IEE Wiring Regulations).

Q ANSI C 80.3-83 Electrical Metallic Tubing, Zinc Coated. R NFPA 70 National Electrical Code (NEC).

S SEC DPS SEC Distribution Planning Standards.

T SEC SDMS SEC Distribution Materials Specifications.

U SEC SDCS SEC Distribution Construction Standards.

1.04 SUBMITTALS

A Comply with section 0133 00.

B Submit for approval, manufacturer's data on all types of electrical raceways, together with samples of the proposed materials including, but not limited to, the following:

1. Manufacturers data and installation instructions.

2. Schedule of materials to be used.

3. Shop drawings showing all layout, connections, wall and floor boxes fixing methods and the like.



4. Trunking sizing calculation and cable tray / ladder loading calculations for the various areas along with shop drawing.

C. All related test reports for loading on ducting, service, junction outlet boxes from a recognized testing institution should be made available for final approval of materials.

1.05 QUALITY ASSURANCE

A Manufacturers: Firms regularly engaged in manufacture of raceways of types and ratings required, whose products have been in satisfactory use in similar service for not less than 5 years. Preference shall be given to local manufacturers and agents/suppliers.

B Installer: Firms regularly engaged and qualified with at least 5 years of successful installation experience on projects with electrical installation work similar to that required for the project.

C Electrical Raceways shall generally be manufacturers standard construction and materials. Where this conflicts with any part of the specification, the contractor shall so state at the time of tender.

1.06 DELIVERY, STORAGE AND HANDLING

A Comply with section 01 61 00.

B Provide color-coded thread protectors on exposed threads of metal conduit. Handle raceways carefully to prevent end-damage and to avoid scoring the finishes.

C Where possible, raceways shall be stored indoors. If necessary to store outdoors, raceways shall be elevated well above ground and enclosed with durable waterproof wrapping.

1.07 WARRANTY


1.08 SEC/MUNICIPALITY COMPLIANCE

A Contractor shall comply with all applicable SEC distribution material specification, construction and planning standards for power distribution networks and municipality specification for road lighting. Some of the specifications and standards are attached with the contract documents for guidance, however contractor shall obtain copy of all applicable specification and standards from the concerned authorities as required on site or instructed by the Engineer.

B Any conflict found between this project specification and SEC or municipality specification/standards shall be immediately brought to the notice of Engineer for final decision.

PART 2: PRODUCTS

2.01 ACCEPTABLE MANUFACTURERS

Not Used.

2.02 PVC CONDUITS



A All PVC conduits and fittings shall be uPVC heavy gauge, rigid type. PVC conduits may be used where ambient temperatures do not exceed 75 o

B All PVC conduits and accessories shall be obtained from the same manufacturer.

C.

C No conduit shall be less than 20 mm diameter.

D Fittings and accessories for PVC conduits shall include, but not be limited to, adapters, junction/pull boxes, bushings, couplings, elbows, nipples, plugs, seals, etc.

E Conduit boxes shall be of circular pattern with appropriate spout entries and 50.8 mm accessory fixing centres.

F All connections and terminations of PVC conduits and fittings shall be by means of the manufacturer's standard adaptor.

G All boxes shall have brass thread inserts for the fixing of accessories or covers.

H All tees shall be made using conduit tee boxes. Tangential entry boxes shall be used where appropriate. Multiple conduits may necessitate the use of large uPVC adaptable boxes for junctions.

I All saddles shall be of the spacer bar type and shall be from the same manufacturer as that of the conduit which they are being used to secure.

J All wall mounted accessory boxes shall have one adjustable fixing lug to facilitate final leveling of accessories.

2.03 ELECTRICAL METALLIC TUBING (EMT)

A All Electrical Metallic Tubing (EMT) and accessories shall conform to NEC article 348 Part-B and ANSI C 80.3; not less than 20 mm (") diameter.

B All EMT and accessories shall be completely free from rust or other defects and shall have the same finish throughout the installation.

C Fittings and accessories for EMT shall include, but not be limited to, adapters, junction/pull boxes, bushings, connectors, couplings, elbows, expansion joints, gaskets, hubs, locknuts, nipples, plugs, seals, etc.

D Fittings and accessories for EMT shall be compression type. Pot metal or die-cast type and "sock-on or drive-on type fittings shall not be used.

E Only standard manufactured fittings and accessories for EMT shall be used. Adaptation between EMT and PVC or RSC shall be through metal boxes.

F All saddles for surface mounted installation of EMT shall be of the space-bar type and of the same finish as that of the EMT, which they are being used to secure.

G All necessary boxes shall have one adjustable fixing lug to facilitate final leveling of accessories.

2.04 RIGID STEEL CONDUITS (RSC)



A All Rigid Steel Conduits (RSC) and accessories shall be heavy gauge welded steel, not less than 20 mm diameter.

B RSC and fittings shall be hot dipped galvanized, providing heavy protection both inside and outside. Steel shall be galvanized after cutting and threading.

C All conduits and fittings shall be threaded, free from rust or other defects and shall have the same hot dipped galvanized finish throughout the installation.

D Fittings and accessories for RSC shall include, but not be limited to, adapters, junction/pull boxes, bushings, connectors, couplings, elbows, expansion joints, gaskets, hubs, locknuts, nipples, plugs, seals, breathers, etc.

E Fittings and accessories for RSC shall be of malleable iron or a mixture of grey iron and cast steel.

F All bushes shall be hexagonal headed, heavy duty, long threaded brass bushes complete with serrated tempered shake-proof washers. All bends shall be cold set. All tees shall be made using circular tee conduit boxes.

G All saddles for surface mounted installation of RSC shall be of the spacer bar type and of the same finish as that of the conduit which they are being used to secure.

H A tapped earth connection facility shall be provided in every box.

I All accessory boxes shall have one adjustable fixing lug to facilitate final leveling of accessories.

J PVC coated RSC and fittings shall be used for cables extending to the outside of buildings and where above grade extensions of PVC Conduits required transition from PVC to RSC.

K PVC coated rigid steel conduits and fittings shall be suitable to house the wires and cables with 90 0

2.05 FLEXIBLE CONDUITS

C conductors. The thickness of the PVC coating shall be a minimum of 0.40 mm. A PVC jacketed coupling shall be provided with each length of conduit. A PVC sleeve equal to the outside diameter of the conduit shall extend 37 mm from each end of the coupling.

A Flexible conduits shall be liquid-tight, constructed from galvanized steel core and continuous liquid-tight PVC jacket, not less than 20 mm diameter.

B Flexible conduits shall only to be used for final connection to items of fixed equipment subject to vibration or movement.

C The liquid-tight PVC jacket of the flexible conduits shall be capable of withstanding 90 o

D All fittings and accessories for liquid-tight flexible steel conduits shall be nylon jacketed.

C cable operating temperatures.

E Nylon jacketed brass adaptors shall be provided for connection at either end of the flexible conduit and should be of the compression type.

2.06 METAL CABLE TRUNKING



A Metal cable trunking shall be used wherever possible to replace multiple conduit runs, subject to the prior approval of the Engineer. It shall be manufactured from galvanized steel sheets.

B Only purpose made bends, tees, risers, end stops, fittings, connectors, covers and accessories by the same manufacturer as the trunking shall be used and finished in hot dipped galvanized steel. Site fabrication shall not be permitted.

C Tinned copper earth straps shall be provided at every joint of the metal cable trunking.

D Covers for metal cable trunking, suspended or fixed on surfaces of walls or under raised floors, shall be of the overlapping type and secured to the trunking by an approved type of fastening arrangement such as clips, etc.

E In outdoor locations and areas subject to corrosive atmospheres, the metal trunking shall be painted with chlorinated rubber paint or PVC/epoxy coating as approved by the Engineer.

F Metal cable trunking shall be single or multi-compartment as required. Where multi-compartment is used, vertical dividers shall be provided between the compartments which shall be welded to the trunking prior to galvanizing.

2.07 CABLE TRAYS

A All cable trays shall be of heavy duty perforated type with return flange.

B All cable trays shall be manufactured from hot-dip zinc coated galvanized steel, with a standard heavy duty galvanizing coating of 350 g/m2

C All accessories and fittings such as bends, tees, elbows, cross units and angles shall be of the same specification as that of the cable tray finish and shall be standard products from the same manufacturer as the cable tray. Site fabrication shall not be permitted.

and Z2 bending grade.

D Cable trays and accessories shall be of thickness not less than:

1. 1.5 mm up to 305 mm width.

2. 2.0 mm above 305 mm and up to 900 mm width.

E All fixing brackets, hangers, supports, threaded rods, etc. shall be finished by hot-dip galvanizing. All fixation hardware (bolts, nuts, washers, etc.) shall be stainless steel.

F Tinned copper earth continuity straps shall be provided at every joint of the cable tray.

G Where cable tray crosses building expansion joints, the tray shall be installed suitably to provide expansion/contraction with the building expansion.

H Where cable tray carries 13.8 kV cable, a tray lid shall be installed.

I In outdoor locations and areas subject to corrosive atmospheres, all cable trays shall be painted with chlorinated rubber paint or PVC/epoxy coating, as approved by the Engineer.

J Submit loading calculations of cable trays for Engineers review and approval before ordering.



K Select the width of cable tray such that a minimum spacing of one cable diameter or twice the cable diameter, as approved by the Engineer, shall be possible to be kept between the two adjacent cables plus the spare future space.

2.08 CABLE LADDERS

A All cable ladders shall be heavy duty (>2 mm), manufactured from hot-dip galvanized steel with a standard heavy duty galvanizing coating of 350 g/m2

B All accessories and fittings such as couplers, bends, tees, elbows, etc. shall be by the same manufacturer as the ladder.

and Z2 bending grade.

C Submit loading calculations of cable ladders and supports in accordance with the manufacturer's loading and structural information for Engineers review and approval and ensure that undue stress or bending shall not occur.

D Tinned copper earth straps shall be provided at every joint of cable ladders.

E In outdoor locations and areas subject to corrosive atmosphere, the ladders shall be painted with chlorinated rubber paint or PVC/epoxy coating, as approved by the Engineer.

F Select the width of cable ladders such that a minimum spacing of one cable diameter or twice the cable diameter, as approved by the Engineer, shall be possible to be kept between the two adjacent cables plus the spare future space.

PART 3: EXECUTION

3.01 INSPECTION


B All Electrical Raceways including conduits, trunkings, trays/ladders and fittings shall be free from objectionable lines, striations, bubbles, welds, and other manufacturing defects that would impair the service of the raceways. The bore of the conduits shall be circular in cross-section with smooth interior surfaces free from rough and flaky areas. Electrical Raceways and fittings shall be free from all substances that injuriously effect any wire or cable covering.

C The routes of all Electrical Raceways including conduit runs are shown diagrammatically on the drawings to outline the general routing only. Any interference with pipes, HVAC ducts, structural members or other equipment shall be inspected and coordinated well before commencement of the installation of raceways. Deviations shall be made in accordance with the approval of the Engineer, at no extra cost to the contract.

3.02 PVC CONDUIT INSTALLATION

A PVC conduits shall be used only where cast into slabs, built or chased into walls etc. Adaptation between PVC and metal conduits shall be through metal boxes.

B PVC conduits shall not be installed in locations exposed to direct sun light.

C Where conduit boxes are not to be fitted with accessories, they shall be fitted with cover plates which shall be overlapping where flush boxes are used.



D PVC conduits shall be jointed and terminated utilizing the following appropriate components as supplied by the conduit manufacturer:

1. Purpose made adaptors and accessories.

2. Permanent adhesive - solvent cement to produce a rigid watertight joint when used with standard couplers and accessories.

3. Flexible adhesive - A non-hardening adhesive to be used where expansion facilities are required in long conduit runs, in conjunction with expansion couplers. Flexible adhesive shall not to be used at building movement joints.

E PVC conduits up to 25 mm diameter may be bent cold with the use of appropriate bending spring obtained from the conduit manufacturer. For larger size conduits, it will be necessary to use heat or appropriate manufacturer's standard ready made bends.

F Adequate allowance shall be made for linear expansion and contraction of conduits under normal working temperature variations and when conduits pass through building expansion joints, as follows:

1. Expansion couplers shall be used on all straight runs of conduit exceeding 6 meter in length.

2. Conduit shall be free to slide within saddles.

G Conduit shall be supported at intervals of 1.5 meter in isolated positions or at 1 meter intervals in accessible situations. Where ambient temperatures are high, this spacing shall be reduced accordingly.

H Multiple conduits may necessitate the use of large PVC adaptable boxes for junctions, which shall be readily accessible at all times.

I Care shall be taken in the support of totally enclosed lighting fittings. Where excessive temperatures are likely to occur, special heat resistant boxes shall be used, i.e. of a pattern specifically designed to improve weight loading characteristics at high temperatures.

J Spacing/fill factors shall be applied to all conduits in accordance with IEE Wiring Regulations.

K Do not install PVC conduits closer than 75 mm to pipes of other services.

L "Draw-in" boxes shall be installed in all conduit runs exceeding 3 meter in length, at a maximum spacing of 12 meter and shall be readily accessible at all times.

M Inspection elbows, bends or tees shall not be permitted for flush installation.

N Use extension rings where boxes are found to be not flush with the finished surface. Care shall be taken to prevent water, dirt, dust or debris from entering the conduit system.

O All bends shall be made such that PVC conduits shall not be damaged, and the internal diameter of the conduits shall not be effectively reduced.

P Not more than three 90 degree bends or a total of 270 degree bends shall be made in one conduit run between outlets, fittings or outlet bodies including any bends located



immediately at the start or end.

Q Install concealed conduits such that only two crossings at a given point occur within a floor or roof slab to prevent any damage or cracking of the slab.

R No conduit shall be allowed to run in the floor screed of toilets, kitchen, bathroom or any other wet area.

S Where cables pass through ducts or sleeves entering buildings, seal the ends of the ducts or sleeves using a special caulking compound of a putty-like consistency. The compound shall be workable with the hands at temperatures as low as 1.7 oC, and shall not slump up to a temperature of 149 o

T Install a nylon fish cord in each empty conduit, complete with cap and bushing at each end. This is applicable to PVC & metal conduits.

U Where conduits are concealed in plaster walls, conduits shall have a minimum 15-20 mm

cover along its whole length. Horizontal runs shall be avoided. V Expansion joints (PVC or GS) shall be provided where applicable to all types of raceways.

C. It shall not harden materially when exposed to air.

3.03 METAL CONDUIT INSTALLATION

A Metal conduits, comprising Rigid Steel Conduits (RSC) or Electrical Metallic Tubing (EMT) shall be installed in exposed and concealed locations as required.

B EMT shall be installed in concealed (not embedded) locations, generally above suspended ceiling and inside shafts. RCS shall be installed exposed on surface at all such locations where conduits are liable to be damaged mechanically and in external locations.

C Threads for RSCs shall be of sufficient length to allow conduits to butt together within couplers. A minimum engagement of five (5) full threads shall be made at all fittings and accessories.

D Remove oil and grease from all threads of RSCs.

E Support all metal conduits at intervals of 1.5 meter in isolated positions or 1 meter intervals in accessible situations.

F Do not install metal conduit closer than 75 mm to pipes of other services.

G All conduit boxes not to be fitted with accessories shall have metal cover plates which shall be overlapping where flush boxes are used.

H 'Draw in' boxes shall be provided in conduit runs exceeding 3 meter in length. 'Draw in' boxes shall be at a maximum 12 meter spacing and shall be readily accessible at all times. Adaptable junction boxes shall also be accessible at all times for inspection and maintenance.

I Care shall be taken to prevent water, dirt and debris from entering the conduit system.

J Use extension rings where boxes are found not to be flush with the finished surface.

K Protect conduits and conduit accessories from rust and mechanical damage. Exposed conduit threads and damaged or rusty portions of metal conduits shall be painted, using an oxide



undercoat and aluminum paint, after being cleaned to bare metal.

L Conduits installed in areas subject to corrosive atmospheres shall be painted with chlorinated rubber paint after the installation is complete.

M Under no circumstances shall any metal conduit be used as a Circuit Protective Conductor (CPC). Every final sub-circuit shall incorporate its own separate Cu/PVC circuit protective conductor.

N Apply spacing/fill factors to all metal conduits in accordance with IEE wiring regulations.

O Make field bends in cold state with a hand bender for 38 mm (1-1/2) and smaller diameter metal conduits only. Larger size conduits shall be bent with a machine bender or be factory supplied. Heating of metal conduits to facilitate bending is not permitted.

P All bends shall be made so that metal conduits shall not be damaged and the internal diameter of the conduit shall not be effectively reduced. The inner edge radius of all field bends shall not be less than the minimum allowable radius as per standards.

Q Not more than three 90 degree bends or a total of 270 degree bends shall be made in one conduit run between outlets, fittings or outlet bodies including any bends located immediately at the start or end.

R Conduits and elbows used for cables extending to outside of buildings shall be PVC coated rigid steel extending one meter from the building foundation. A concrete encased PVC adapter shall be used where cables extending outside the buildings are to run in PVC ducts. Bells shall be provided on PVC horizontal stub outs.

S PVC conduits shall not be extended above grade. Where extensions of PVC conduits above grade are required, a PVC coated rigid steel transition bend shall be used having PVC/steel coupling on one end and threaded male or female adaptor on the other end. The PVC coated rigid steel transition bend or conduit shall extend a minimum of 150 mm above grade. A concrete envelope 100 mm high shall be formed around such risers to minimize corrosion at the point of emergence. The top of the envelope shall be sloped for drainage.

T Verify exact stub up locations and termination requirements for items and equipment being served, for all necessary power and control wiring.

U Where cables pass through ducts or sleeves entering buildings, seal the ends of the ducts or sleeves using a special caulking compound of a putty-like consistency, which shall be workable with the hands at temperatures as low as 1.7 oC, and shall not slump up to a temperature of 149 o

V Where conduits turn out of, or penetrate, a slab they shall be spaced at not less than 65 mm on centers.

C and shall not harden materially when exposed to air.

W Location and sizing of conduit sleeves passing through floors and walls that are not shown on the Drawings shall be the responsibility of the Contractor. All sleeves shall be rigid galvanized steel unless indicated otherwise, extended 150 mm above floor and capped when not in use. Space between conduits and sleeves shall be filled with approved sealant to a minimum of 50 mm deep at top and bottom of conduit sleeve.

X All metal conduits entering any gasketed boxes or gasketed equipment enclosure shall be provided and terminated with gasketed hubs with bonding screws. Metal conduits entering



non-gasketed sheet-metal boxes or enclosures shall be provided and terminated with general purpose hubs.

Y Provide supports to alleviate stress on cables where they enter a conduit or other enclosure from the tray.

Z All conduit and trunking in unconditioned and unfinished areas e.g. plant rooms, electrical rooms, etc. shall be painted with one coat of metal primer after installation.

AA Attach clamps to masonry walls by means of expansion shields. Use beam clamps or 'Caddy Fasteners' or equivalent to attach conduits to exposed steel work.

BB Provide expansion couplings with bonding jumpers and clamps for all conduits crossing

building expansion joints. CC Provide conduit fittings with suitable covers on runs of exposed conduit. Each conduit fitting

shall be of a type suitable for its particular use. Covers shall be located so that they will not be blocked by the future installation of additional conduits.

DD Running couplers with lock nuts shall not be permitted, only three piece conduit unions shall

be accepted. EE Run exposed conduits in groups, parallel to building lines, and accurately in line and level. FF Install conduits so that there is no interference with access openings in ceilings, removal of

ceiling tiles, or access to any equipment in the ceiling space. GG Do not run conduit through structural steel members, concrete beams or columns except as

permitted by the Engineer. HH Do not run conduits larger than 25 mm in structural floor slabs without prior approval of the

Engineer. Do not run any embedded conduit, in floor slabs less than 100 mm thick, unless approved by the Engineer.

II Protect conduit stub-ups from damage during construction, and seal the ends to prevent the

entrance of foreign material with plastic plugs or other approved devices. Taping or similar protection is not acceptable.

JJ Where conduits pass through a waterproof membrane, install sleeves with a 50 mm wide

collar continuous welded all around, at membrane level. Ensure that the membrane is dressed over the collar. Sleeves shall be sized large enough to allow free passage of the conduits. Make the sleeves watertight sealer after the conduits are installed.

KK Where conduits pass through other floor slabs or fire walls, seal into the concrete or pass

through a sleeve. Sleeves shall be high density plastic, with flange for attaching to form work or structure. Pack the sleeve with fireproof packing and seal approved by the Engineer.

LL Where runs of conduit are shown, only the general routing and location are indicated. Install

all conduits so as to provide a maximum head room and minimum interference with the space. Install conduits as close to the structure as possible, so that furring can be kept to a minimum.

MM Take out and replace at no change to the contract price any conduit or cable which is not



installed properly in the opinion of the Engineer. NN Where conduits are connected to trunking, steel boxes, panels, switchgear, or any item not

having a tapped entry (or having a tapped entry of 6mm or less), the connections shall be made by long threaded male brass bushes with a coupling and serrated spring washer after removing a paint with a purpose made tool.

OO Bushes shall be tightened with a tool specifically designed for that purpose. Pliers or toothed

wrenches shall not be allowed. PP Separate conduit shall be provided for each circuit, unless otherwise approved by the

Engineer, and for each system wiring. 3.04 FLEXIBLE CONDUITS INSTALLATION

A All flexible conduits and fittings used shall be liquid-tight.

B Flexible conduits shall only be used in lengths of less than 1000 mm, in cases where a final connection is required to be made to a fixed item of equipment which is subject to vibration or thermal expansion.

C Flexible conduits shall be 1.25 x L in length, L being the direct distance between connection unit and fixed appliance, up to maximum length of 1 meter.

D Purpose made glands shall be used on the ends of all lengths of flexible conduits.

E A separate Cu/PVC circuit protective conductor shall be included in all lengths of flexible conduits.

F Flexible conduits shall be installed so as not to incur undue mechanical strain, damage or excessive temperatures.

3.05 METAL CABLE TRUNKING INSTALLATION

A Cable trunking shall be fixed securely to the building structure at intervals not exceeding 1.5 meter.

B Spacing/fill factors shall be applied to all cable trunking in accordance with IEE Wiring Regulations.

C For metal trunking installations, earth continuity shall be ensured by means of tinned copper earth straps bolted across each joint. Flexible braided straps shall be used for expansion joints.

D Metal trunking cut during installation shall have cut ends painted with an oxide undercoat and an aluminum top coat.

E Where metal trunking is installed in areas subject to corrosive atmospheres, the complete trunking installation shall be painted with a chlorinated rubber paint after the installation is complete.

F Expansion joints with gaps shall be incorporated in all cable trunking runs in excess of 6 meter in length. External couplings shall have elongated slots and fixing holes shall be drilled oversize to give freedom of linear movement. Internal couplings shall be securely fixed at one end by use of thixotrophic adhesive leaving the other end free for linear movement.



G Bare copper or aluminum cables shall not be run in metal trunking.

H All conduit and trunking in unconditioned and unfinished areas e.g. plant rooms, electrical rooms, etc. shall be painted with one coat of metal primer after installation.

I Install trunking runs neatly on the surface and be truly vertical, horizontal or parallel with the

features of the building.

J Use multi-compartment trunking where segregation of services is required, and shall consist of earthed steel partitions of not less than 1.0 mm thickness.

K Compartments shall be drilled to allow conduits to pass through to the compartment served.

L In the situations where tees and junctions are encountered, the multi-compartment fittings

shall be of such a depth as to allow for suitable pass-over connections.

M Fire barriers shall be provided within the trunking at each crossing of fire wall or fire zone.

N Insulated pin racks shall be provided to support cables in vertical runs exceeding 3 meters. Removable cable restraining straps shall be 'sprung' into trunking at 600 mm centers where trunking covers are fixed on the underside or side of the trunking.

O Trunking covers shall be of maximum length for the run, drip-proof. Close fitting and of

similar protective coating as the trunking. Cover joints shall not coincide with trunking joints, but be staggered, thus producing a more rigid construction. Covers shall only be installed on the underside of trunking in unavoidable circumstances, and then only with agreement in writing.

P Trunking up to 50 mm wide shall have only one screw at each fixing point, trunking over this

width shall have two screws. Screws shall be sheardised Class 1 or stainless steel, No. 12 for up to 75 mm width, No. 14 for larger sizes.

Q Connections to distribution boards shall be made by using flanges giving the full trunking

capacity, making due allowance for the future installation of cables from spare ways.

R Connections between trunking and apparatus shall be by means of a brass male bush coupling and internally serrated washer or alternatively a standard flanged coupling.

S The cover shall be removable over the whole length of the trunking. Where trunking passes

through walls or floors a small length of cover must be provided on the section passing through to form a sleeve for 25 mm on each side.

3.06 CABLE TRAYS/LADDERS INSTALLATION

A Where practical, cable trays/ladders shall be run horizontally and flat or vertically and shall be supported at distances not exceeding 1.5 meter to the building structure using mild steel brackets. These brackets shall be secured to the building structure using expansion shield bolts and washers or built into the building structure during construction.

B Where cable tray/ladder is suspended, 2 drop rods shall be used at each suspension point to an angle iron or channel support to which the cable ladder is bolted. The spacing of suspension points shall be determined in accordance with the manufacturer's structural information such that undue stress or deflection does not occur.



C Where cable tray/ladder is cut, the open ends shall be painted using an oxide undercoat and an aluminum top coat. Where the finish is PVC, a top coat of liquid PVC solution shall be applied after the completion of the cable ladder installation.

D Cable trays/ladders to be run parallel with walls shall not be mounted closer than 75 mm to the wall.

E Secure all cables to cable trays/ladders at distances in accordance with manufacturers recommendations and IEE Wiring Regulations up to Engineers satisfaction and approval to withstand any expected mechanical stress during short circuit or seismic conditions.

F Do not run bare copper or aluminum cables on cable tray/ladder.

G Ensure earth continuity by means of tinned copper earth straps bolted across each cable tray/ladder joint. Flexible braided straps shall be used for expansion joints.

H Sizing of cable trays shall allow 30% spare capacity for future cables.

I Sets and bends shall be sized to allow for the minimum permissible radius of the largest cable on the tray. Cables shall retain their relative positions on bends and sweeps.

J Cable trays shall be cut along a line of plain metal and not through perforations. Burrs or

sharp edges shall be removed prior to the installation of tray sections or accessories.

K Bushes shall be provided through all holes cut in the body of the tray.

L Avoid mid span joints and position the joints as close to the support as is practical. Fixing of supports shall be by "Rawl bolts" or equal as approved by the Engineer.

M Alternatively, proprietary steel channel may be used, permitting easy adjustment and

modification.

N Proprietary clamps fixing onto the flanges of structural beams may be used.

O Cables shall be installed on trays / ladders in a single layer and in accordance with the IEE Wiring Regulations, using plastic coated, metal reinforced clips or saddles and by proprietary cleats of a pattern recommended by the cable manufacturer.

P Not more than four cables shall be secured by a single clip or saddle. Binding tape fixings

must not be used. On vertical tray / ladder installations load bearing cleats or saddles shall be used and securely fixed to the tray / ladder.

Q Where cables in tray pass through a floor or fire barrier, interrupt the tray and provide an

Electro-tray cable transit with openings sized for the cables.

R Cable trays shall be provided with standard stand and ventilated cover to protect cables from sun radiation when installed outdoors and to protect cables form mechanical damage where damage is likely to occur during maintenance activities.

END OF SECTION

SECTION 26 05 33PART 1: GENERALSection includeSElectrical raceways and accessories including, but not limited to the following:

Related sectionsSUBMITTALsComply with section 0133 00.

Electrical Raceways shall generally be manufacturers standard construction and materials. Where this conflicts with any part of the specification, the contractor shall so state at the time of tender.DELIVERY, STORAGE AND HANDLINGComply with section 01 61 00.Provide color-coded thread protectors on exposed threads of metal conduit. Handle raceways carefully to prevent end-damage and to avoid scoring the finishes.Where possible, raceways shall be stored indoors. If necessary to store outdoors, raceways shall be elevated well above ground and enclosed with durable waterproof wrapping.

PART 2: PRODUCTSPVC CONDUITSAll PVC conduits and fittings shall be uPVC heavy gauge, rigid type. PVC conduits may be used where ambient temperatures do not exceed 75 PoPC.All PVC conduits and accessories shall be obtained from the same manufacturer.No conduit shall be less than 20 mm diameter.Conduit boxes shall be of circular pattern with appropriate spout entries and 50.8 mm accessory fixing centres.All connections and terminations of PVC conduits and fittings shall be by means of the manufacturer's standard adaptor.All boxes shall have brass thread inserts for the fixing of accessories or covers.All tees shall be made using conduit tee boxes. Tangential entry boxes shall be used where appropriate. Multiple conduits may necessitate the use of large uPVC adaptable boxes for junctions.All saddles shall be of the spacer bar type and shall be from the same manufacturer as that of the conduit which they are being used to secure.All wall mounted accessory boxes shall have one adjustable fixing lug to facilitate final leveling of accessories.

RIGID STEEL CONDUITS (rsc)All Rigid Steel Conduits (RSC) and accessories shall be heavy gauge welded steel, not less than 20 mm diameter.RSC and fittings shall be hot dipped galvanized, providing heavy protection both inside and outside. Steel shall be galvanized after cutting and threading.All conduits and fittings shall be threaded, free from rust or other defects and shall have the same hot dipped galvanized finish throughout the installation.All bushes shall be hexagonal headed, heavy duty, long threaded brass bushes complete with serrated tempered shake-proof washers. All bends shall be cold set. All tees shall be made using circular tee conduit boxes.All saddles for surface mounted installation of RSC shall be of the spacer bar type and of the same finish as that of the conduit which they are being used to secure.A tapped earth connection facility shall be provided in every box.All accessory boxes shall have one adjustable fixing lug to facilitate final leveling of accessories.

FLEXIBLE CONDUITSFlexible conduits shall be liquid-tight, constructed from galvanized steel core and continuous liquid-tight PVC jacket, not less than 20 mm diameter.Flexible conduits shall only to be used for final connection to items of fixed equipment subject to vibration or movement.Nylon jacketed brass adaptors shall be provided for connection at either end of the flexible conduit and should be of the compression type.

METAL CABLE TRUNKINGMetal cable trunking shall be used wherever possible to replace multiple conduit runs, subject to the prior approval of the Engineer. It shall be manufactured from galvanized steel sheets.Only purpose made bends, tees, risers, end stops, fittings, connectors, covers and accessories by the same manufacturer as the trunking shall be used and finished in hot dipped galvanized steel. Site fabrication shall not be permitted.Tinned copper earth straps shall be provided at every joint of the metal cable trunking.Covers for metal cable trunking, suspended or fixed on surfaces of walls or under raised floors, shall be of the overlapping type and secured to the trunking by an approved type of fastening arrangement such as clips, etc.In outdoor locations and areas subject to corrosive atmospheres, the metal trunking shall be painted with chlorinated rubber paint or PVC/epoxy coating as approved by the Engineer.Metal cable trunking shall be single or multi-compartment as required. Where multi-compartment is used, vertical dividers shall be provided between the compartments which shall be welded to the trunking prior to galvanizing.

2.07 CABLE TRAYSAll cable trays shall be of heavy duty perforated type with return flange.All cable trays shall be manufactured from hot-dip zinc coated galvanized steel, with a standard heavy duty galvanizing coating of 350 g/mP2P and Z2 bending grade.All accessories and fittings such as bends, tees, elbows, cross units and angles shall be of the same specification as that of the cable tray finish and shall be standard products from the same manufacturer as the cable tray. Site fabrication shall no...Cable trays and accessories shall be of thickness not less than:All fixing brackets, hangers, supports, threaded rods, etc. shall be finished by hot-dip galvanizing. All fixation hardware (bolts, nuts, washers, etc.) shall be stainless steel.Tinned copper earth continuity straps shall be provided at every joint of the cable tray.Where cable tray crosses building expansion joints, the tray shall be installed suitably to provide expansion/contraction with the building expansion.Where cable tray carries 13.8 kV cable, a tray lid shall be installed.

2.08 CABLE LADDERSAll cable ladders shall be heavy duty (>2 mm), manufactured from hot-dip galvanized steel with a standard heavy duty galvanizing coating of 350 g/mP2P and Z2 bending grade.All accessories and fittings such as couplers, bends, tees, elbows, etc. shall be by the same manufacturer as the ladder.Submit loading calculations of cable ladders and supports in accordance with the manufacturer's loading and structural information for Engineers review and approval and ensure that undue stress or bending shall not occur.Tinned copper earth straps shall be provided at every joint of cable ladders.In outdoor locations and areas subject to corrosive atmosphere, the ladders shall be painted with chlorinated rubber paint or PVC/epoxy coating, as approved by the Engineer.

PART 3: EXECUTIONPVC CONDUIT INSTALLATIONPVC conduits shall be used only where cast into slabs, built or chased into walls etc. Adaptation between PVC and metal conduits shall be through metal boxes.Where conduit boxes are not to be fitted with accessories, they shall be fitted with cover plates which shall be overlapping where flush boxes are used.PVC conduits shall be jointed and terminated utilizing the following appropriate components as supplied by the conduit manufacturer:PVC conduits up to 25 mm diameter may be bent cold with the use of appropriate bending spring obtained from the conduit manufacturer. For larger size conduits, it will be necessary to use heat or appropriate manufacturer's standard ready made bends.Adequate allowance shall be made for linear expansion and contraction of conduits under normal working temperature variations and when conduits pass through building expansion joints, as follows:Conduit shall be supported at intervals of 1.5 meter in isolated positions or at 1 meter intervals in accessible situations. Where ambient temperatures are high, this spacing shall be reduced accordingly.Multiple conduits may necessitate the use of large PVC adaptable boxes for junctions, which shall be readily accessible at all times.Care shall be taken in the support of totally enclosed lighting fittings. Where excessive temperatures are likely to occur, special heat resistant boxes shall be used, i.e. of a pattern specifically designed to improve weight loading characteristics a...Spacing/fill factors shall be applied to all conduits in accordance with IEE Wiring Regulations.Do not install PVC conduits closer than 75 mm to pipes of other services."Draw-in" boxes shall be installed in all conduit runs exceeding 3 meter in length, at a maximum spacing of 12 meter and shall be readily accessible at all times.Inspection elbows, bends or tees shall not be permitted for flush installation.Use extension rings where boxes are found to be not flush with the finished surface. Care shall be taken to prevent water, dirt, dust or debris from entering the conduit system.

METAL CONDUIT INSTALLATIONMetal conduits, comprising Rigid Steel Conduits (RSC) or Electrical Metallic Tubing (EMT) shall be installed in exposed and concealed locations as required.EMT shall be installed in concealed (not embedded) locations, generally above suspended ceiling and inside shafts. RCS shall be installed exposed on surface at all such locations where conduits are liable to be damaged mechanically and in external loc...Threads for RSCs shall be of sufficient length to allow conduits to butt together within couplers. A minimum engagement of five (5) full threads shall be made at all fittings and accessories.Remove oil and grease from all threads of RSCs.Support all metal conduits at intervals of 1.5 meter in isolated positions or 1 meter intervals in accessible situations.Do not install metal conduit closer than 75 mm to pipes of other services.All conduit boxes not to be fitted with accessories shall have metal cover plates which shall be overlapping where flush boxes are used.'Draw in' boxes shall be provided in conduit runs exceeding 3 meter in length. 'Draw in' boxes shall be at a maximum 12 meter spacing and shall be readily accessible at all times. Adaptable junction boxes shall also be accessible at all times for insp...Care shall be taken to prevent water, dirt and debris from entering the conduit system.Use extension rings where boxes are found not to be flush with the finished surface.Protect conduits and conduit accessories from rust and mechanical damage. Exposed conduit threads and damaged or rusty portions of metal conduits shall be painted, using an oxide undercoat and aluminum paint, after being cleaned to bare metal.Conduits installed in areas subject to corrosive atmospheres shall be painted with chlorinated rubber paint after the installation is complete.Under no circumstances shall any metal conduit be used as a Circuit Protective Conductor (CPC). Every final sub-circuit shall incorporate its own separate Cu/PVC circuit protective conductor.Apply spacing/fill factors to all metal conduits in accordance with IEE wiring regulations.

FLEXIBLE CONDUITs INSTALLATIONAll flexible conduits and fittings used shall be liquid-tight.Flexible conduits shall only be used in lengths of less than 1000 mm, in cases where a final connection is required to be made to a fixed item of equipment which is subject to vibration or thermal expansion.Flexible conduits shall be 1.25 x L in length, L being the direct distance between connection unit and fixed appliance, up to maximum length of 1 meter.Purpose made glands shall be used on the ends of all lengths of flexible conduits.A separate Cu/PVC circuit protective conductor shall be included in all lengths of flexible conduits.Flexible conduits shall be installed so as not to incur undue mechanical strain, damage or excessive temperatures.

METAL CABLE TRUNKING INSTALLATIONCable trunking shall be fixed securely to the building structure at intervals not exceeding 1.5 meter.Spacing/fill factors shall be applied to all cable trunking in accordance with IEE Wiring Regulations.For metal trunking installations, earth continuity shall be ensured by means of tinned copper earth straps bolted across each joint. Flexible braided straps shall be used for expansion joints.Metal trunking cut during installation shall have cut ends painted with an oxide undercoat and an aluminum top coat.Where metal trunking is installed in areas subject to corrosive atmospheres, the complete trunking installation shall be painted with a chlorinated rubber paint after the installation is complete.Expansion joints with gaps shall be incorporated in all cable trunking runs in excess of 6 meter in length. External couplings shall have elongated slots and fixing holes shall be drilled oversize to give freedom of linear movement. Internal couplings...Bare copper or aluminum cables shall not be run in metal trunking.

3.06 CABLE TRAYS/LADDERS INSTALLATIONWhere practical, cable trays/ladders shall be run horizontally and flat or vertically and shall be supported at distances not exceeding 1.5 meter to the building structure using mild steel brackets. These brackets shall be secured to the building stru...Where cable tray/ladder is suspended, 2 drop rods shall be used at each suspension point to an angle iron or channel support to which the cable ladder is bolted. The spacing of suspension points shall be determined in accordance with the manufacturer'...Where cable tray/ladder is cut, the open ends shall be painted using an oxide undercoat and an aluminum top coat. Where the finish is PVC, a top coat of liquid PVC solution shall be applied after the completion of the cable ladder installation.Cable trays/ladders to be run parallel with walls shall not be mounted closer than 75 mm to the wall.Secure all cables to cable trays/ladders at distances in accordance with manufacturers recommendations and IEE Wiring Regulations up to Engineers satisfaction and approval to withstand any expected mechanical stress during short circuit or seismic c...Do not run bare copper or aluminum cables on cable tray/ladder.Ensure earth continuity by means of tinned copper earth straps bolted across each cable tray/ladder joint. Flexible braided straps shall be used for expansion joints.

Documents

SECTION 26 05 33-ELECTRICAL RACEWAYS.pdf