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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].
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Electrical Lighting & Cable Selection D.K.Pathirana
Part 1 Finding required number of luminaries
Types of Electrical Lighting • Ambient lighting • Task Lighting • Accent lighting
Lumen(Luminous flux) [F] • The lumen is defined such that… • At frequency of 540×1012hz, (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
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… Averageilluminanceon the working plane after a specified period of use of a lighting installation to the averageilluminanceobtained 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
Load calculation Part 2
Design power socket outlets….. If not given • Then analyse….
Total load for the new wing = Total load for ground floor+1st floor+2nd floor…… = 13.503+……+…… =49.29Amp
Bill Of Quantity (BOQ) • Example
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 In It ___________ and InIb CaCi CgCf It = Maximum current capacity of cable for given temp. Ib = Design current In = Rated current of the protective device Ca = Correction factor for ambient temperature. CI = Correction factor for thermal insulation Cg = Correction factor for grouping Cf = Correction factor for semi enclosed fuse. (for MCBs Cf = 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.. • Ib rated current of protective diviceIz Where, Ib = Design service current Iz = Maximum current carrying capacity of the conductor • If 1.45 x Iz Where, Iz = Maximum current carrying capacity of the conductor If = Thermal tripping current of MCCB