SECTION 26 0533
RACEWAY AND BOXES FOR ELECTRICAL SYSTEMS
PART 1 - GENERAL
Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division 01 Specification Sections, apply to this Section.
1.01 SECTION INCLUDES
A. This Section to include the supply, installation and commissioning of all conduit works in accordance with the Project Documentation.
1. Rigid PVC conduit and fittings
2. Rigid Steel conduit and fittings
3. Flexible Steel conduit and fittings
1.02 SUBMITTALS
A. Samples: Cut-away samples of all sizes of conduits, conduit boxes and fittings of each type fixed to a board and submit.
B. Product Data: When submitting samples submit manufacturer’s details, catalogues and copies of test certificates confirming that offered types comply with the Specification. C. Shop Drawings: Submit drawings of proposed conduit layouts and obtain approval
before commencing work.
D. Comply with ISO 9002 (BS 5750: Part 2).
E. Shop Drawings: For the following raceway components. Include plans, elevations, sections, details, and attachments to other work:
1. For handholes and boxes for underground wiring, including the following:
a. Duct entry provisions, including locations and duct sizes.
b. Frame and cover design.
c. Grounding details.
d. Joint details.
F. Coordination Drawings: Conduit routing plans, drawn to scale, on which the following items are shown and coordinated with each other, based on input from installers of the items involves:
1. Structural members in the paths of conduit groups with common supports.
2. Plumbing items and architectural features in the paths of conduit groups with
common supports.
G. Source quality-control test reports.
1.03 QUALITY ASSURANCE
B. Conform to the related latest BS for metallic and non-metallic conduits and accessories stipulated in this Section.
C. Coordinate layout and installation of raceway and boxes with other construction elements to ensure adequate headroom, working clearance, and access.
1.04 RELATED STANDARDS
A. All electrical installations shall be carried out in accordance with the best International Standards and Codes of Practice specifically with the current issue of IEE Regulations (BS 7671) and the requirements of the local electrical power supply authority.
B. Wherever reference is made to a British Standard (BS), a British Standard Institution recognized equivalent European Standard would also comply. Each type of equipment/ material selected shall comply with either the BS or the European Standard.
C. Listed below are the standards and codes referred to in this section.
1. BS 31 Steel conduit and fittings for electrical wiring.
2. BS 731 Flexible steel conduits and adapters for the protection of electric
cable.
3. BS 2782 Methods of testing plastics.
4. BS 4568 Specification for steel conduit and fittings with metric threads of
ISO form for electrical installations. Steel conduit, bends and couplers.
5. BS 4607 Non-metallic conduits and fittings for electrical installations rigid
PVC conduits and conduit fittings.
6. BS EN 50086 Specification for conduit systems for electrical installations. 7. BS EN 60423 Conduits for electrical purposes. Outside diameters of conduits for
electrical installations and threads for conduits and fittings
8. BS EN 61386 Conduit systems for cable management
9. BS EN 10327:2004 Continuously Hot-Dip Strip and Sheet of low carbon steels
PART 2 - PRODUCTS
2.01 AVAILABLE MANUFACTURERS
A. PVC conduits and accessories
1. Decoduct (UAE)
2. EGA (KSA)
3. Clipsal (Australia)
4. Approved Equal.
B. Galvanized Rigid Steel Conduits and Accessories
1. REXWAY – Malaysia 2. Allied - USA 3. Barton (UK) 4. Approved Equal. C. Cable Trunking 1. ICMS - QATAR 2. Wiremold (UK) 3. Barton (UK) 4. Approved Equal. 2.02 GENERAL
A. Light and power circuits, fire alarm, telephone, signal and other low current system wiring shall be drawn in conduits unless otherwise indicated
B. Conduit system shall generally be concealed and installed as indicated, unless otherwise indicated. Minimum conduit size shall be 20mm diameter.
C. Light and power circuits, fire alarm wiring, telephone wiring, signal wiring and low current system wiring shall each be run in separate conduit and wire way.
D. Cable insulated for two different categories of circuit shall be segregated. E. Irrespective of service, conduit and fitting used shall be:
1. Where embedded: heavy gauge rigid PVC complying to BS 4607.
2. Where surface mounted, exposed: galvanized rigid steel conduit (GRS) as per BS
4568
3. Where installed above false ceilings and in voids: GRS
4. Where installed in flame proof and hazardous areas: GRS
5. From terminal box to machine/ device: flexible steel conduit as per BS 731. 6. Liquid tight flexible steel in wet/ damp areas.
2.03 RIGID PVC CONDUIT AND FITTINGS A. Standards:
1. Conduit and fittings shall comply with BS 4607: Part 1 & 2 and CEE Publication 26. In addition, conduit and fittings shall comply with this specification where requirements are more stringent.
B. Physical Properties:
a. Resistant to high temperatures
b. Non-hygroscopic
c. Self-extinguishing
d. Of adequate insulation resistance and electric strength
e. Inert to all liquid normally discharged from residential, commercial and industrial premises
f. Suitable for installation, storage and transportation at temperatures
normally below -5°C. or above 85°C. and at these temperatures shall not:
1) Soften or suffer any structural degradation
2) Show signs of cracking, or deform so that cables cannot be easily drawn in or are likely to be damaged when drawing in, when bent, compressed or exposed to extreme temperature
g. Of adequate mechanical strength and thermal stability
h. Suitably and indelibly marked and identified. Markings shall include
nominal size and be easily legible
i. Smooth inside and outside and free from burrs and sharp edges. Surfaces
and corners over which cables may be drawn shall be smooth and well rounded.
2. Sizes of Conduit:
a. Minimum 20 mm, internal diameter unless otherwise indicated
b. Where size is not indicated: select in accordance with the regulations and as proper to the number and size of conductors.
Conduit Dimension Minimum Wall Thickness Heavy Gauge - mm 20mm 1.8 25mm 1.9 38mm 2.5 50mm 2.8 3. Fittings:
a. Conduit entries shall be designed to ensure a watertight joint.
4. Expansion fittings:
a. Provide fittings that provide expansion and contraction for at least 0.06 mm per meter of length of straight run per degree of temperature change. b. Provide expansion fittings for each of the following locations and provide type and quantity of fittings that accommodate temperature changes listed below:
1) Outdoor locations not exposed to direct sunlight: 70°C, 5°C
temperature change.
2) Outdoor locations exposed to direct sunlight: 86°C, 5°C
temperature change.
3) Indoor spaces: 70°C, 5°C temperature change.
5. PVC Conduit Boxes:
a. PVC Conduit Boxes can be used through PVC Conduit raceway system
and shall comply with BS 4607
b. metallic conduit boxes as specified elsewhere in this section can be used alternatively if required for PVC conduit raceway system
c. all boxes shall be provided with tapped brass inserts for fixing the screws d. all boxes for switches, sockets, outlets, etc., shall be rigid PVC or metallic type and their dimensions shall be suitable for fixing the switches, sockets and other accessories.
2.04 RIGID STEEL CONDUIT AND FITTINGS A. Rigid Steel Conduit
1. All metallic conduits shall comply with BS 4568 Part 1 & 2 and of Class 4 rigid steel screwed type and to BS 31 Class “B” (strictly for size 1 ½” (38mm) and 2” (50mm)), having an interior and exterior zinc coating of uniform quality and appearance throughout all surfaces
2. Conduits shall not be less than 20 mm diameter size, and shall be complete with all necessary threaded fittings, couplings and connecting devices having galvanized equivalent finish Conduit Dimension Minimum Wall Thickness Heavy Gauge - mm 20mm 1.6 ± 0.15 25mm 1.6 ± 0.15 32mm 1.6 ± 0.15 38mm Nom: 1.8288mm Min: 1.7272mm 50mm Nom: 2.032mm Min: 1.9304mm
3. Conduits and fittings shall be manufactured specially for electric wiring purposes. When manufactured by a continuous weld process, weld beads both inside and outside the tube shall be completely removed prior to galvanizing
4. All conduits and fittings shall be free from rust or other defects on delivery to the site and shall be properly stored in covered racking so that it is protected from mechanical damage and damage by weather and water whilst stored on the site 5. All conduits shall be coupled to boxes and trunking wires using brass male bushes.
All such bushes shall be hexagon headed, heavy duty long threaded type
6. All conduit expansion couplings used shall be fabricated from material equal or
equivalent to that of the conduit with which the coupling is to be used, having factory installed packing ring and pressure ring to prevent entrance of moisture. All coupling shall be equipped with earthing ring or earthing conductor
7. All conduit runs shall be fixed using spacer bar pattern saddles giving not less than 3 mm clearance between the conduit and the surface to which it is fixed. Saddles shall have finish to match the conduit and saddle clips shall be secured to the bar by means of brass screws.
B. Metallic Conduit Boxes:
1. Metallic conduit boxes shall be used throughout metallic conduit raceway systems, and shall comply with, or be of demonstrated equivalent quality and performance to BS 4568 requirements. All boxes and covers shall be galvanized, zinc plated or rust-proof finish equivalent to conduit finish
2. Circular and/or rectangular boxes shall be used for pull boxes and terminating
boxes, according to size and number of conduits connected to box. Boxes shall be either malleable iron or heavy duty steel construction with welded joints and tapped holes to receive metal threaded cover retaining screws. Self tapping screws will not be permitted
All boxes, other than those to which a fitting or accessory is to be directly mounted shall be fitted with covers screwed to the box by brass screws. Covers shall be made of hot dipped galvanized steel.
All cover and accessory fixing provisions shall be so positioned that the fixing screws lie completely clear of cable entering the box. All fixing screws shall be of brass
3. All boxes installed in exterior locations, plant rooms, ducts, etc., shall be fitted with approved type gaskets to provide a waterproof seal between box and cover or other items fitted to the box and shall be IP 56 rated.
4. All boxes provided as junction boxes where cable joints are specified or permitted, shall be provided with fixed terminal blocks. Such boxes shall be of suitable size to contain the terminal block and sufficient cable to allow neat connections to be made. The terminal blocks shall be fixed to the box by brass screws and shall comprise brass conductor connectors, with brass clamping screws enclosed in porcelain or other heat resisting insulation material which will not distort or otherwise have its properties damaged by temperatures below the highest temperature at which the insulation of any cable connected to it is destroyed.
2.05 FLEXIBLE CONDUIT AND CONNECTIONS A. Flexible Conduit:
1. To BS 731, Part 1, watertight, PVC sheathed, spiraled metal type. The conduit shall be terminated at boxes and equipment by means of approved compression glands
2. To be of the unpacked type for normal atmospheric conditions and non-asbestos
packaged for damp situations. Adapters shall be of the solid type
3. Flexible conduit shall be used for the final connection of rigid conduit to the terminal boxes of machines fitted with a means of drive adjustment and/or where vibrations is likely to occur.
4. Length of flexible conduit for recessed and semi-recessed light fixtures shall be maximum 1.5 meters.
B. Flexible Connections:
1. Where connections to electrical machines are to be by multicore glands, the final termination shall be by ring type universal glands and locknuts, and adequate slack cable in the form of a loop or spiral being left to allow for the movement of motors necessitated by belt re-tensioning, vibration, etc.
2.06 HINGED COVER ENCLOSURES AND CABINETS A. Design
1. Surface-mounted or free-standing type, fabricated from zinc coated or galvanized
sheet steel minimum 1.5mm thick, Paint finish as approved for distribution boards.
2. Fixed cover and padlocked hinged door; operable without obstruction.
3. Protected IP-31 for internal and IP-65 for outdoor use.
2.07 CABLE TRUNKING
A. Steel Trunking and Accessories: Factory made BS 4678: Part 1, from minimum 16 SWG sheet steel to BS EN 10327: 2004, with 15 microns zinc coating.
B. Trunking Covers: Manufacture to fit firmly on the body. Design of covers and fixings shall prevent wires entangling on them. Covers shall be attached and removed from trunking with simple tools.
C. Accessories (Bends, Tees, Flanged Connectors etc.): Factory made by the trunking manufacture.
D. Multi-compartment Trunking: Provide 16 SWG galvanized steel segregation barriers without sharp edges.
E. Cable Retaining Clips: Galvanized spring ‘W’ wire type.
PART 3 - EXECUTION
3.01 PREPARATION A. Sets and Bends:
1. Conduits up to 32 mm diameter; form on site with an approved bending machine
using proper formers, guides, springs, etc., taking care not to deform conduit.
2. Conduits over 32 mm diameter: use coupling fittings.
3.02 INSTALLATION OF CONDUIT
A. General
1. Run conduit in square, symmetrical lines, parallel to or at right angles to walls and in accordance with the accepted practice
2. Conduit system shall be mechanically continuous and watertight after installation. All conduit system shall be arranged wherever possible to be self draining
3. Conduit runs between draw-in positions shall conform to local Regulations regarding number of bends and extent of straight run
4. Conduit fill shall generally be less than 45%.
5. Keep conduits at least 100 mm from pipes and other non-electrical services 6. Where conduit runs are to be concealed in the structure or are to pass through floor
slabs, the Contractor shall be responsible for marking the accurate positions of all chases and holes on site. The Contractor shall arrange the conduit routing to make maximum use of any preformed conduit holes and slots provided in structural beams. Conduit installation on shear walls shall be kept to a minimum. All routings necessary on shear walls shall be agreed with the Engineer’s Representative before work is put in hand
7. Install conduits so as not to interfere with ceiling inserts, lights or ventilation outlets. 8. Earth continuity of steel conduits shall be mechanically & electrically continuous
throughout.
9. Provide pull wire in all empty conduits. B. Runs in Reinforced Concrete:
1. Obtain approval for placing PVC conduits before pouring concrete
2. Run conduits in concrete slabs parallel to main reinforcing steel
3. Additional openings in finished slabs, where approved, shall be made by drilling, not by breaking
4. Conduit boxes shall not be nailed to shuttering boards. C. Horizontal or Cross Runs:
1. To be avoided in partitions and side walls.
D. Surface Mounted Conduit (including conduit installed above false ceiling):
1. Fix with distance spacing saddles to allow conduits to be taken directly into
accessories without bends or sets. E. Concealed Conduit:
1. Fix securely to prevent movement before casting of concrete and screeds,
application of plaster and the like
2. Spacing of clips shall be not greater than as follows:
Conduit size Spacing
b. 32-38 mm 900 mm
c. 50 mm 1000 mm
3. Supports for exposed conduit shall be fixed at each side of bends. F. Expansion Fittings:
1. Fix in conduit wherever it crosses as expansion joint in the structure to which it is fixed.
G. Terminations:
1. Make with a flanged coupling, lead washer and hexagonal male brass bush, where
conduit runs terminate in cable trunking, distribution boards or any sheet metal structure.
H. Conduit Boxes:
1. Fix at all outlet points.
3.03 INSTALLATION OF FLEXIBLE CONDUIT
A. All conduits must be secured to outlet boxes, junction boxes or cabinets by placing locknuts on outside of box and locknuts and bushings on the inside of box.
B. Conduits connecting recessed fixtures and their adjacent junction boxes must be flexible metallic conduit 20 mm minimum size and shall be of sufficient length to permit dropping of the fixture below the ceiling and to gain access to the junction box.
C. Conduit to motors shall be terminated in the conduit fittings on the motors, the final connection being made with liquid tight flexible conduit and suitable liquid tight connectors.
D. A green insulated 4 mm2 (minimum) tinned copper earth connection shall be made between the solid conduit or cable sheath and the equipment, the copper cable being run inside the flexible conduit. Couplings fitted to removable covers or non-metallic equipment etc. shall be bonded to the earthing terminal of the equipment etc. Where changes to flexible conduits occur, a watertight outlet box with threaded entries shall be inserted and the earth connection made to an internal terminal. The cover screws shall not be used for earthing connections.
3.04 INSTALLATION OF ENCLOSURES AND CABINETS
A. Anchor enclosures and cabinets securely to wall and structural supports at each corner.
3.05 INSTALLATION OF CABLE TRUNKING A. Install trunking with lid on top or side.
B. Support trunking at 1.0m intervals with trapeze type hangers or wall brackets. C. Retain cables in trunking with cable retaining clips.
D. Support cables in vertical runs with pin-type supports at maximum 15m centers. E. On vertical runs exceeding 6m support cable with projecting pin-type supports with heat
F. Make connections to accessories with pop riveted or welded joints. Radius or gusset bends and tees.
G. Provide tinplated copper link at joints and terminations.
H. Fire-stop cable trunking at floor slabs and at fire walls by packing inside the trunking with mineral wool.
I. Provide galvanized draw wire in every trunking conduit which is left for wires and cables. Not less than 300mm slack shall be left at each end of the draw wire.
3.06 FIRESTOPPING
A. Install conduits sealing where they enter or leave hazardous locations. Provide firestopping at fire compartment areas. Locate fittings at suitable, approved, accessible locations and fill them with approved sealing compound.
B. Firestopping materials and installation requirements are specified in Division 07 Section “Firestopping.”
3.07 CLEANING
A. The conduit outlets when installed and before wiring shall be temporarily closed by means of well fitting wooden plugs, and immediately before cables are drawn in, conduits systems shall be thoroughly swabbed out until they are dry and clean. B. Upon completion of installation of system, including outlet fittings & devices, inspect
exposed finish, remove burrs, dirt & construction debris and repair damages finish including chips, scratches & abrasions.
3.08 PROTECTION
A. Provide final protection and maintain conditions in a manner acceptable to Site Engineer to ensure that coating, finishes & cabinets are with out damage or deterioration at substantial completion.
B. Repair damage to galvanized finishes with zinc rich paint recommended by manufacturer.
C. Repair damage to PVC or paint finishes with matching touch up coatings per manufacturer’s recommendations.
