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Table 1: Standard Category A lighting installation, including power to ceiling-mounted fan coil units.
Installation to open plan office floor, based on CIBSE LG 3 category 2 recessed luminaires with 2 x 28 w T5 lamps on a 3 m x 3 m grid (net internal floor area: 28 400 m2)
Wiring Method Traditional   Prefabricated   Busbar   
(£) (£/m2) (£) (£/m2) (£) (£/m2)
Traditional single core cables drawn into conduit and trunking installation 391 800 13.8        
Prefabricated wiring installation     160 700  5.66     
25 A busbar installation         209 000  7.36 
Lighting control installation including lighting control modules, common group switching with capability to be locally switched 131 600 4.63 131 600 4.63 131 600 4.63
Luminaires - CIBSE LG 3 Category 2 recessed with 2 x 28 W T5 lamps 284 000 10 284 000 10 284 000 10
Recessed compact downlighters to supplement lighting around atrium and in lobby areas 106 400 3.75 106 400 3.75 106 400 3.75
Emergency luminaires 108 600 3.82 108 600 3.82 108 600 3.82
Fan coil unit electrical supplies: Fused connection unit wired by single core cables drawn into conduit installation fed from lighting trunking 119 400 4.2        
Fused connection units wired from a common prefabricated wiring installation     33 800  1.19     
Fused connection units fed by busbar tap-off units and flexible leads         26 500  0.93 
Total installation cost 1 141 800 40.2 825 100 29.05 866 100 30.5
Extra over costs of lighting installation for revised layout: 3 m x 1·5 m chequerboard grid using 600 mm x 600 mm luminaires with 3 x 18 W T8 lamps            
Single core cables in conduit and trunking 293 900 10.35        
Prefabricated wiring installation     144 600  5.09     
25 A busbar installation         167 200  5.89 
Lighting control installation 125 000 4.4 125 000 4.4 125 000 4.4
Luminaires 335 100 11.8 335 100 11.8 335 100 11.8
Emergency luminaires 128 100 4.51 128 100 4.51 128 100 4.51
Total extra over cost of revised layout 882 100 31.06 732 800 25.8 755 400 26.6
Adjustment factors for alternative lighting control installations to open-plan offices.For analogue dimmable lighting control: lighting control installation +5%; luminaires +20%; emergency luminaires +12% For digital dimmable lighting control: lighting control installation +5%; luminaires +30%; emergency luminaires +18%
Table 2: Installation to shell and core stair cores, based on compact fluorescent luminaires (net floor area: 505 m2)
Wiring Method Traditional   Prefabricated   Busbar 
(£) (£/m2) (£) (£/m2) (£)
Traditional single core cables drawn into conduit and trunking installation 10 700 21.19     n/a
Prefabricated wiring installation     21 100 41.78 n/a
Compact fluorescent luminaires 13 700 27.13 13 700 27.13 n/a
Emergency luminaires 10 000 19.8 10 000 19.8 n/a
Total Installation 34 400 68.12 44 800 88.71 n/a
Installation to shell and core toilet blocks, based on 50 W 12 V LV downlighters (net floor area: 1 200 m2)          
Traditional single core cables drawn into conduit and trunking installation 18 100 15.08     n/a
Prefabricated wiring installation     23 000 19.17 n/a
50 W 12 V lv downlighters 40 900 34.08 40 900 34.08 n/a
Emergency luminaires 13 100 10.92 13 100 10.92 n/a
Total Installation 72 100 60.08 77 000 64.17 n/a
The following exclusions relate to both tables: inflation beyond third quarter 2000, distribution boards and circuit protection devices (included in lv distribution element), fixing of fuse connection units to fan-coil units (factory fitted by others) air handling extract slots (cut separately into ceiling tiles by others), builder’s work in connection, construction manager or main contractor’s organisational management fees and attendances, contingency and design reserves, professional fees, tax allowances, vat.