B7.5.1 Scope
This Sub-section covers lighting installations (mainly pole mounted) for street lighting, security lighting, floodlighting and general area lighting.
Section B7
B7.5.2 Specification and Drawing
External lighting installations shall be installed in accordance with the Particular Specification and Drawings. Unless otherwise specified, poles and luminaires shall comply with the Standard/Guided Drawings . B7.5.3 Luminaire
The type of lamps and luminaires to be used shall be as specified in the Particular Specification and Drawings. Unless otherwise specified, the luminaires shall be securely mounted on the poles by the method indicated on the Standard/Guided Drawings.
For those not mounted on poles, they shall be fixed on wall or hanger, plinth or the like dedicated for the mounting of the luminaires. In such case, the installation shall comply with Section B3.
Where specified in the Particular Specification, a safety chain shall be provided between the luminaire and the lamp pole to ensure that the luminaire will not be dropped down in case the luminaire support fails. The chain shall be galvanized steel and of adequate strength to support at least three times the weight of the luminaire.
B7.5.4 Construction of Lamp Pole
Unless otherwise specified, lamp poles shall be constructed of mild steel pipe of one, two or three sections of diameter and modules, all as specified on the Standard/Guided Drawings. The lamp poles shall be hot dipped galvanized to BS 729. Pole caps, cat ladders and platforms shall be fitted where shown and as required. Material samples and working drawings shall be submitted when requested by the Architect. The poles shall be finished overall with at least two coats of primer and two coats of finishing paint after erection in accordance with Sub- section A3.12. The colour of the finishing paint shall be as directed by the Architect.
If imported lamp poles are offered, the Contractor shall submit evidence to substantiate that the lamp poles are structurally sound and are suitable for use in the local environment, in particular under typhoon conditions at a wind speed of up to 160 knots. Such evidence may be by means of manufacturer’s calculation and certificates.
All lamp poles shall be earthed by approved means via the armour of the underground armoured cables.
B7.5.5 Foundation of Lamp Pole
Lamp poles shall be securely bolted down in an upright position to the foundations constructed in accordance with the Standard/Guided Drawings. Should there be any queries on the construction of the foundations, the Architect’s advice shall be sought.
B7.5.6 Service Box
A mild steel service box shall be provided on each pole at an appropriate height above ground level to accommodate the MCB control box. The construction of the service box and the MCB control box shall be as shown on the Standard/Guided Drawings.
Each lamp circuit shall be protected by an MCB. Where the CSA of the incoming/outgoing cable cores are larger than that which can be accommodated by the terminal of the MCB, a fixed insulated connector block of adequate rating shall be installed with a tail to the MCB. Alternatively, a copper busbar may be used.
Where the service box serves more than one circuit, the supply to the MCB shall be by means of a copper busbar of adequate rating. The phase conductors of the incoming/outgoing cables shall then be terminated to the busbar by means of cable sockets.
Each control box shall be fitted with a neutral block of adequate rating and having sufficient number of ways for the incoming/outgoing cable cores. It shall be securely fixed to the base of the control box by means of a 6mm thick paxolin block.
The service box shall be fitted with a 3mm thick galvanized mild steel cover made waterproof with a 3mm thick soft rubber or neoprene gasket. The cover shall be fixed by means of four M6 brass fixing bolts and washers and shall be hinged. Provision shall be made in the batten plate of the box for supporting and terminating up to three numbers of incoming/outgoing XPLE or PVC/SWA & PVCS cables by means of suitable cable glands. The cable sizes shall be as specified in the Particular Specification or on the Drawings.
B7.5.7 Underground Cable to Pole
Underground cables for external lighting systems shall be copper cored, XPLE or PVC insulated, steel wire armoured and PVC sheathed cables (XPLE or PVC/SWA & PVCS) unless otherwise specified. Cables shall enter and leave the pole below ground level and each cable shall terminate in a gland fixed to the MCB control box. The cable cores between the glands and the terminals shall not be in tension.
Underground straight through joint will not be permitted without written agreement of the Architect.
All underground cables shall be laid inside cable trenches or ducts. If these ducts are provided by the builder, the Contractor shall ascertain that the quantity, size and associated arrangement of the ducts are suitable for drawing of cables in future. Draw pits of adequate sizes shall be provided for a straight run of approximately 12m, at position where cable route changes direction or as and where required.
Section B7
B7.5.8 Cable between Service Box and Luminaire
Cables from the neutral terminal block and the MCB to the luminaires shall be PVC insulated and PVC sheathed having CSA as specified. Arrangements shall be made to prevent the cores from being under tension where they are attached to terminals. All cables shall be contained within the poles. Rubber grommets shall be installed where cable passes through metal work.
Where sustained arc voltage of a discharge lamp exceeds 250V, the cables used for connecting the lamp and the control-gear shall be of 600/1000V grade to IEC 60502 or as recommended by the lamp manufacturer. The length of cables shall not exceed the limit as recommended by the manufacturer.
Where flexible cables are recommended by manufacturer for termination at the luminaire, PVC insulated and PVC sheathed flexible cables shall be used. Such cables shall enter the luminaire by means of suitable waterproof compression glands.
Where four or more floodlights are mounted on a pole, the flexible cables shall be connected to the luminaires by means of a mild steel connector box with waterproof hinged cover. The connector box shall be fitted near to the top of the pole, all as shown on the Standard/Guided Drawings.
B7.5.9 Switch Fitted to Pole
Where specified switches may be mounted on the pole for local control. Switches mounted on the pole shall be fixed onto it by tapped holes and brass fixing screws. The switches shall be waterproof or contained within a waterproof type galvanized metal case, with an external galvanized metal operating knob or handle. Switches shall be fitted at least 2m above finished ground level.
B7.5.10 Control Gear for Discharge Lighting
Control gear for discharge lamps shall be contained within a galvanized steel box mounted on the pole or inside the concrete gear-cabinet provided by others as shown on the Drawings. When mounted on the pole, the steel box shall be watertight and positioned at a height higher than normal working level in such a way that a ladder is needed for access. The box shall be of adequate size to accommodate all control gear, cable and connections. The method of construction shall be similar to the service box.
B7.5.11 Testing of Illumination Level
Testing of the illumination level and distribution of external lighting installations shall be carried out after dark under the direction of the Architect. All labour, instruments and materials necessary to carry out the test shall be provided including adjustment of the luminaires to
achieve the desired illumination level and performance to the satisfaction of the Architect.
B7.5.12 Numbering of Lamp Pole
All lamp poles shall be marked with appropriate identification numbers. The numbers shall commence consecutively from the source of power supply in the clockwise direction. The numbering proposal shall be submitted with the shop drawings to the Architect for approval.
The number shall be etched on a stainless steel plate which shall be fixed onto the pole by tapped holes and two brass fixing screws. The numbers shall not be less than 50mm tall.
A framed drawing indicating the location of lamp poles and pole numbers shall be provided in the appropriate switch room. The framed drawing shall be fixed onto the wall in such a manner that it can easily be removed for reference.