Electrical Lighting & Cable Selection D.K.Pathirana

Part 1 Finding required number of luminaries

Types of Electrical Lighting Ambient lighting Task Lighting Accent lighting

Ambient lighting

Task lighting

Accent Lighting

Lumen(Luminous flux) [F] The lumen is defined such that… – At frequency of 540×10 12 hz, (i.e., at wavelength λ=555nm) 1 watt of radiant flux (power) will emit 683 lumens of light (luminous flux).

Illuminance (E) Defined as the luminous flux (lumens) falling on a surface per unit area normal to the surface. The unit of illuminance is the Lux

Luminaries

Required no. of Luminaries E x Lx W N = _______________________ NL x  x MF x UF x LLD E= Required Illuminance (Lux level) L = Room length (m) W = Room width (m) NL = Number of lamps in each luminaries N = Number of luminaries  = Lamp flux M = Maintenance factor UF = Utilization factor LLD = Lamp Lumen Deterioration factor

Maintanance factor (MF) Can be defined as… Average illuminance on the working plane after a specified period of use of a lighting installation to the average illuminance obtained under the same conditions for a new installation.

Lamps Lumen Deterioration (LLD) Manufacturer data…. Examples.. Compact fluorescent 0.85 Mercury vapor 0.79 Metal halide 0.83 High pressure sodium 0.91

Reflectance factor the fraction of radiant energy that is reflected from a surface Examples- 70%, 0.8,... Here 10 times the reflection factor….. 1.Ceiling 2. Walls 3. Floor\Working plane.

Room Index K = (LXW)/ [(H1-H0)X(L+W)] Where, L= Room Length (m) W= Room Width (m) H1= Height of luminaire’s light emitting surface H0= Height of the working plan

Utilization factor Room Index (K) Reflectance

Example for lighting calculation sheet LengthWidth heigh t of height of theRoom Reflec tion Utiliza tion Maintan ance Deterior ation Requi red Install ed Lam p Number of Requir edTotalCategory of lumin aries working planeindex factor sfactor lux levelflux desi gnlamps in lumina ires loadbulb lum ens each luminaire W LAMP, T8, 1200MM, 36W, 3500K FT18W/2G11/ FT36W/2G11/

Recommended Lighting Levels Activity Illumination (lux, lumen/m 2 ) Public areas with dark surroundings Simple orientation for short visits Working areas where visual tasks are only occasionally performed Warehouses, Homes, Theaters, Archives150 Easy Office Work, Classes250 Normal Office Work, PC Work, Study Library, Groceries, Show Rooms, Laboratories 500 Supermarkets, Mechanical Workshops, Office Landscapes750 Normal Drawing Work, Detailed Mechanical Workshops, Operation Theatres 1,000 Detailed Drawing Work, Very Detailed Mechanical Works Performance of visual tasks of low contrast and very small size for prolonged periods of time

Load calculation Part 2

Design power socket outlets….. If not given Then analyse…. Ground Floor Quantity Load (Amp) 13A Socket Outlets610*(1+(6-1)*0.2) Florecent Fittings 2x36W32(36*2*32)/(0.7*230) Compact lamps (18W) Compact lamps (36W) Spot lights Shaver socket Basic Lighting Load per Floor40.509Amp. Per Phase load L-GR Amp.

Total new Load for the new wing=49.29Amp Total KVA =(49.29*1.732* 400)/1000 =34.15KVA Add 10 % Extra Capacity= 37.6KVA Amp Closest Next is= 50KVA72.17 Total load for the new wing = Total load for ground floor+1 st floor+2 nd floor…… = ……+…… =49.29Amp

Bill Of Quantity (BOQ) Example Quantity Cost rate(Rs) Total cost(Rs) 01 Phillips 20W CFL warm light =40*425 = Pillips T8 Fluorescent lamp 18W =32*600 =19200 = =36200

Part 3 Cable selection and Over load Protection

Basic types of MCB’s TYPE B TYPE C TYPE D

Sizing the cables length of the wire Check the following inequality I n I t  ___________ and I n  I b C a C i C g C f I t = Maximum current capacity of cable for given temp. I b = Design current I n = Rated current of the protective device C a = Correction factor for ambient temperature. C I = Correction factor for thermal insulation C g = Correction factor for grouping C f = Correction factor for semi enclosed fuse. (for MCBs C f = 1)

Contd… Refer IEE wiring regulation book Lesser than 4% voltage drop….

Selecting a protective device Nature of the load Rated current of the conductor Environmental conditions

Contd.. I b  rated current of protective divice  I z Where, I b = Design service current I z = Maximum current carrying capacity of the conductor I f  1.45 x I z Where, I z = Maximum current carrying capacity of the conductor I f = Thermal tripping current of MCCB

Single Line Diagram

Questions……

Thank you