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Flashcards in Lighting Deck (180)
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0

Emergency lighting in means-of-egress areas must have an intensity of no less than ______ fc (Fill in the Blank)

Building codes require a minimum of 1 fc at the floor level of areas that serve as means of egress. For assembly occupancies, such as an auditorium or theater, the level may reduced to 0.2 fc during performances, but must be automatically restored to 1 fc upon activation of the buildings fire alarm system. Exceptions to the minimum include U, guest rooms in group R-1, dwelling rooms, and sleeping rooms in Groupds R-2 and R-3 occupancies. Sleeping rooms in Group 1 occ are also exempt.

2

How are ballasts rated for sound?

A=quiet; F=noisy

6

A _________ is used to turn on and off to regulate the flow at intermediate rates. Even when wide open, the flow is somewhat restricted. a. Globe Valve b. Gate valve c. Angle valve d. Check valve

a. Globe Valve

11

What are veiling reflections/reflected glare?

Light sources that can be seen on a surface. They involve task and light source.

12

What is the difference between illuminance and luminance?

Illuminannce = E (In); Luminance = L (Leaving) Illuminance measured in fc Luminance measured in footlambert

13

Candlepower is analogous to what in the electrical and hydraulic systems?

Cp are alanogous to voltage (electrical) or pressure (hydraulic)

14

Lumens are analogous to what in the electrical and hydraulic systems?

Lumens are analogous to amperes (electrical) or flow (hydraulic)

15

What is the thing is measured in photometric power? What is photometric power?

Lumens are a measure of photometric power, meaning it is perceived by the human eye as a function of physiology

16

What agency has worked to rationalize lighting design?

Illuminating Engineering Society of North America

24

What is the color rendering index (CRI)? How is it measured?

Measured how closely the perceived colors of an object illuminated with daylight of the same color temp. Max CRI is 100 so a rating of 85 is good

25

What is max lux for energy budget?

2.3 W/sq ft

26

Describe Low Pressure sodium lighting.

Up to 150 lm/W, produces yellow light, used for street lighting

27

High Pressure Sodium (HPS)

80 – 140 lm/W, uses Hot sodium Vapor

28

What are the primary advantages of incandescent lamps?

1. low cost 2. instant start and restart 3. simple, inexpensive dimming 4. simple, compact installation 5. cheap fixtures 6. focusability as a point sorce 7. high power factor 8. lamp life independent of number of starts 9. skin flattering, full spectrum color

29

What are the primary disadvantages of incandescent lamps?

1. low efficacy 2. short lamp life 3. critical voltage sensitivity

30

Because of its poor energy characteristics incandescent lamps should be limited to what application?

1. where use is infrequent 2. where there is frequent short duration use 3. where low cost dimming is required 4. where minimum initial cost is required 5. where good color rendering is required

31

What shapes are reflector lamps made in?

R, BR, ER, PAR

32

What are the advantages of reflector lamps?

accurate beam control narrow=spot wide=flood

37

Which os the following would NOT maximaize daylighting while minimizing solar heat load? A. horizontal shades B. light shelves C. tinted glass D. building shape

C. tinted glass Although tintied glass would reduce the heat load, it would not be good for maximizing daylighting. Low e glass or super windows with clear glazing would be more appropriate. All other choices would be good ways to minimize direct sunlight on the glass while improving transmitted light to the interior of the building

39

The angle of the sun's orientation relative to due south is called A. altitude B. azimuth C. declination D. Solar angle

B. azimuth

40

What is sun declination?

The angle of the north south axis of the earth relative to the sun. It's what causes seasons to happen throughout the year.

41

How are fluorescent lamps designated?

Type,wattage,diameter,color,method of starting

42

What is efficacy? How is it measured 

The ratio of luminous flux emitted to the toal power input tot eh source; measured in lumens per watt

43

A footlambert is is the unit of....?

luminance

Luminance is the luminous flux per unit of projected area and unit solid angle leaving a surface, either reflected or transmitted.

44

 Luminance takes into account...

 the reflectance and transmittance properties of materials and the directions from which they are viewed. 

45

How is luminance calculated?

It's calculated by multiplying the reflectance of material times the illluminance. 

46

Whichof the following types of lamps provides the best color rendition of skin tones?

A. cool white flourescent

B. incandescent

C. mercury vapor

D. metal halide

indandescents 

An incandescent has a high color rendering index (CRI) and a low color temperature, with a predominance of light in the red range. 

A cool white flourescent lamp has more blue and green light and its spectral distribution makes skin tones appear more gray and washed out. oth mercury vapor and metal halide lamps have poor color rendering indexes and are not appropriate for lighting areas where skin tone rendition is important. 

47

The zonal cavity method of calculating average illumination on the work surface for a given number of luminaires depends on which of the following variable? (choose 4)

 

A. angle of light

B. dirt accumulation

C. efficacy of the lamp

D. lumens per lamp

E. room size

F. wall reflectance

B. dirt accumulation

D. lumens per lamp

E. room size

F. wall reflectance

THe zonal cavity method is used to calculate the total number of luminaires required to achieve the desired average illumination on the work surface, which is asusmed to be 30 in above the floor. The variables considered in the calculation include the level of illumination desired, the area of the room, the number of lamps in wach luminaire, the lumen output of each lamp, the coefficient of utilization, the light loss factor (LLF) wall reflectance, and the gradual loss of light due to dirt accumulation. 

48

What is the zonal caivty method used for?

It's used to calculate the total number of luminaires required to achieve the desired averageillumination on the work surface, which is assumed to be 30 inches AFF. 

49

What are the variables considered in calculating the zonal cavity method?

-level of illumination desired

-the area of the room

-the number of lamps in each luminaire

-the lumen output of each lamp

-the coefficient of utilization

-light loss factor

-wall reflectance

-and teh gradual loss of light due to dirt