1. Objectives Finish commercial electrical systems
Learn about lighting system in buildings
Terminology
Lamp types

2. Electrical Systems for Commercial
Example:

3. Panel D Duplexes (receptacles) Phase total 60 kVA, 14kVA (neutral)
30 poles

4. Panel D Duplexes (receptacles) 3 Phase total 60 kVA, 14kVA (neutral)
30 poles
60 kVA / (208V √3 ) = 167A
Select: 200 A panel and same size conductors for all three phases
Neutral same like a phase 200 A
Hot wires should be 250 MCM, Neutral #2/0 aluminum
2½ inch conduit

5. Transformer capacity P = I V ∙√3 =200∙208∙√3 = 72 kVA ~ 75 kVA
SD switch selection:
For transformer: I1E1=I2E2
I2 = I1E1/E2 = 200∙208 / 480 = 86 A
Select switch rated for 100 A
For 100 A rated switch select: Three #1 (aluminum)
and one #1 for neutral (aluminum)
90A fuse for phases

6. Lighting Panel 100A - 20 poles
Hot: 65kVA/(480V∙√3) = 78 A - #2 Aluminum
Neutral: 22 kVA /277V = 79 A - #2 Aluminum
Select 100 A three pole fused switch
1½ inch conduit

7. Power Panel No neutral? – all three phase circuits
33 poles required – chose 42 standard size and allows for expansion
165kVA/(480 √3) = 198 A
Choose 225A switch (could use 200 A, but you count on expansion)
3 300 MCM aluminum wires – 2 inch conduit
(in the book table you don’t have MCM 300, however it exist)

8. Wireway
198A + 86 A + 78 A = 362A
400A would allow for some expansion, some would probably go to 600A
400A three-pole switch
Six 250 MCM (unlikely to find conductors big enough to just have 3) and one #2/0 aluminum
Neutral current: maximum = 117 A, you can expand neutral too (130 A)

9. Summary Panel Sizing Find panel power usage and neutral usage
Size panel conductors and associated conduit and switches

10. Summary of Electrical Systems
Power generation transport and voltage transformation
AC/DC Fundamentals
Equipment
Residential Buildings
Commercial Buildings
NEC code

11. Lighting Source: DOE HVAC is largest component of energy use
Lighting is second
Lighting might be smaller portion – including cooling to make up for heat of lighting
Energy isn’t only criteria,
Source: DOE

12. Motivation
Lighting represents a third of commercial building energy use
Lighting has been measured to influence:
Worker productivity
Retail sales
Mood/emotion/comfort
Accident avoidance/safety

13. Vision and light Brightness, pattern, motion, and color
Which is more sensitive – eye or camera?
Which is more important, brightness or contrast?

14. Color Does color change the apparent size of rooms?
Does color change perception of temperature, noise, elapsed time?

15. Want is light ? Light – electromagnetic radiation Radiation wavelength
Visible light 0.4 – 0.7 μm

16. Solar radiation spectrum
Major part of solar radiation is visible light

17. Photometrics Luminous intensity [candela, cd]
Define the ability of light source to generate light (illumination) in given direction
Power – luminous flux [lumen, lm]
Quantity of light
Illuminance – light power density [foot-candela, fc]
[lux, lx] SI units
Density of light (illumination) incident on a surface
Luminance - surface brightness [foot-lambert, lm/ft2]
directional emission of visible light

18. Relation
between:
1) Luminous
intensity [cd]
and
2) Illuminance [fc]
fc = cd / distance2

19. Units and conversion 1 cd = Area of unit sphere = 4·π = 12.57 lumens
Luminous flux [lumen]= Luminous intensity [cd] · (4·π)
Illuminance [foot-candle, lux] = Luminous flux [lumen]/Area [ft2,m2]
Luminance [Foot-lambert] = lumen/ft2 from surface in the direction of view
– define the brightness of surface – important for contrast
r=1
1cd

20. Important quantities Chapter 14.2 (Tao and Janis)
Sections: , , , 1
Ref: Tao and Janis (2001)

21. Major design parameters
Lighting systems (lamps):
Define Luminous flux [lumen]
Required level of light at design spot (table spot on the wall etc.)
Defined by Illuminance level (E)

22. Illuminance (E) depends on angle Example:
Spot light with luminous intensity I= 5000cd is aimed at painting at the wall 5 ft from the light and the angle φ=45°.
What is the illuminance level (E) at the center of the painting?

23. Solution Distance: Illuminance orthogonal to the beam E=I/L2=5000/
Ebeam= 100 fc
Illuminance orthogonal to the painting
Epainting= Ebeam/
Epainting=71 fc

24. Color of light
Color temperature is used to express the color of the light

25. Surface color rendering
Depending on the light type the surface colors can be different Depends on spectral energy distribution

26. Color rendering
lamp source can cause a color shift

27. Terms for Lamps What is luminous efficacy?
What does a lifetime of 1000 hours mean?
What affects lifetime?
Does color rendering index (CRI) indicate if a lamp source will cause a color shift?

28. Luminous efficacy
Define the light output per unit of electric power input
Efficacy = Lumens/Watt

29. Ref: Tao and Janis (2001)

30. Incandescent Thomas Edison first incandescent lamp
Efficacy of 1.4 lumens/watt
Life – 750 to 1000 hours
10 – 20 % decay in output

32. Specialty Incandescent Lamps
Halogen
Low voltage
Long-life
Infrared
Interference filters

33. Is Dimming Bad For Incandescent Lamps?
- 10% lower Voltage
- 25% lower light
- life of lam double

34. Fluorescent Lamps Electrodes arc through mercury vapor
Phosphors fluoresce in visible range
Efficacy of 60 to 100 lumens/watt (after burn-in)

35. Reading Assignment Tao and Janis Sections: 14.1
14.2.3, , , ,
14.4
15.1, 15,2, 15.3, 15.4