Republic of the Philippines
CAMARINES NORTE STATE COLLEGE
F. Pimentel Avenue, Brgy. 2, Daet, Camarines Norte
COLLEGE OF ENGINEERING
ENU 1– ENGINEERING UTILITIES
MODULE 7
Title: Artificial Lamps
Characteristics of Artificial Lighting
Lamp – is a device that generates light in layman term frequently called a light bulb, the term lamp (rather than bulb) is
used in the lighting industry to avoid confusion when describing a light source. Lamps are rated by efficacy, life and
color temperature, and rendition.
Bulb – is the glass portion of a lamp that encloses and protects the working parts of the light source, whereas a lamp
is a source of light.
Luminaire – is a complete lighting unit, which consists of a lamp (or lamps), lamp socket(s), any lenses, refractors, or
louvers, any ballast, and the housing. (fluorescent troffers, downlights, spot or accent lighting, and outdoor area and
flood lighting)
Lighting fixture – is the luminaire less the lamp(s). (it includes the structural parts of a luminaire including any lenses,
mounting supports, wiring, and a ballasts, but does not include the lamps.)
Two broad categories of lamps.
1. filament lamps – a filament lamp is a common type of light bulb. It contains a thin coil of wire called the
filament. This heats up when an electric current passes through it, and produces light as a result. The resistance of a
lamp increases as the temperature of its filament increases. (incandescent lamps, r and par, tungsten-halogen)
2. gaseous discharge – gas discharge lamps are a family of artificial light sources that generate light by
sending an electric discharge through an ionized gas, a plasma. Gas discharge tubes (GDTs) are used to protect
personnel and sensitive equipment from hazardous transient voltages.
a. low-pressure discharge lamps (fluorescent lamps and the low-pressure sodium lamps)
b. high pressure or high-intensity discharge (HID) lamps – are a type of electrical gas-discharge lamp
which produces light by means of an electric arc between tungsten electrodes housed inside a
translucent or transparent fused quartz or fused alumina arc tube. HID lamps are typically used when
high levels of light over large areas are required, and when energy efficiency and/or light intensity are
desired. These areas include gymnasiums, large public areas, warehouses, movie theaters,football
stadiums, outdoor activity areas, roadways, parking lots, and pathways. (mercury vapor, metal halide,
and high pressure sodium lamps)
Light Output
Luminous flux – is the measure of the perceived power of light expressed in lumens (lm). Technically, a lumen is
defined as the quantity of light given through a steradian by a source of one candela of intensity radiating equally in all
directions.
Candela (cd) – SI unit of luminous intensity that is, the power emitted by a light source in a particular direction. One
candela is one lumen per steradian. Technically, a candela is the luminous intensity, in a given direction, of a source
that emits a monochromatic radiation
Luminous Efficacy
Luminous efficacy – is the ratio of the light output of a light source (a specific lamp) to the electrical energy consumed
(including the ballast if applicable) to produce that light source. It is expressed in units of lumens per watt of electric
power (lm/W) and is thus typically referred to as LPW.
LPW = light output (lm)/power input (W)
Luminous efficacy is a good measure of the efficiency of a bare lamp. It will decrease over the life of the lamp because
lamp output declines over time
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Republic of the Philippines
CAMARINES NORTE STATE COLLEGE
F. Pimentel Avenue, Brgy. 2, Daet, Camarines Norte
COLLEGE OF ENGINEERING
Example:
Determine the luminous efficacy of the following lamps:
a. A 40 W incandescent lamp that emits 505 lm of light
LPW = light output (lm)/power input (W)
= 505 lm/40 W = 12.6 lm/W
b. A 40 W fluorescent lamp (and 4 W ballast) that emits 3050 lm of light
LPW = light output (lm)/power input (W)
= 3050 lm/44 W = 69.3 lm/W
Correlated Color Temperature
The color of a lamp can be rated by its correlated color temperature (CCT) in degrees Kelvin (K), the SI unit of
temperature.
1000°F (800 K), a black body begins to glow with red light;
5000°F (3000 K) it emits bright yellow light;
8500°F (5000 K) it gives off white light;
14 000°F (8000 K) the black body emits a soft blue light.
Warm light – color temperature is less than 3500 K
Cool lighting – color temperature is greater than 5000 K
Daylighting – color temperature is between temperatures of 4500 and 6500K, with the lower side of the range warmer
and the upper side cooler.
The approximate color temperature, in degrees Kelvin (K),
of various theoretical (black body), natural, and artificial light sources
Color Rendering Index
Color rendering index (CRI) is a method of numerically comparing the color distribution of a light source to a reference
lamp.
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Approximate color rendering index (CRI) for different commercially available lamps
Spectral power distribution curve
Is a graphic presentation of the quantities of light emitted by a lamp by a wavelength component.
 A spectral power distribution curve of an ordinary household incandescent lamp will typically
show a large increase in radiant power from 380nm to 780nm.
 This type of lamp illuminates yellow, orange and red-colored objects very well. Violets and
blues are not illuminated as well.
Monochromatic low-pressure sodium lamps
 Frequently used to illuminate street intersections typically have a spectral power distribution curve
that is concentrated between 589nm and 589.6nm.
 This lamps renders all surfaces in an orange-yellow version of blacks and white.
Lamp Life
The rated life of a lamp is its median life expectancy, expressed in hours. Lamp life generally decreases each time a
lamp is switched on and off.
Example: A lamp manufacturer’s specifications for a 40 W fluorescent lamp indicates an output of 2680 lm, a rated life
of 20 000 hr and a cost of $6.00 per lamp. Data for a 150 W incandescent lamp indicates an output of 2850 lm, a rated
life of 750 hr, and a cost of $2.00 per lamp. When in use, it is anticipated that these lamps will be operated 10 hr per
day, 220 days per year
a. For each lamp, approximate the time period that elapses before replacement is necessary.
150 W incandescent lamp:
750 hr/(220 days/year x 10 hr/day) = 0.34 years (4.1 months)
40 W fluorescent lamp:
20 000 hr/(220 days/year x 10 hr/day) = 9.1 years (110 months)
b. Approximate the cost of each type of lamp over a 10-year period, assuming use and lamp costs remain constant.
150 W incandescent lamp:
10 years/0.34 years per lamp = 29.4 lamps
29.4 lamps over 10 years @ $2.00 per lamp = $58.80
40 W fluorescent lamp:
10 years/9.1 years per lamp = 1.1 lamps
1.1 lamps over 10 years @ $6.00 per lamp = $6.60
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Type of Artificial Light Sources
Incandescent Lamps
Composed basically of a sealed glass containing a filament connected at its ends to the contract area in the
base thereby completing an electric circuit.
The glass envelope comes in a variety of shapes and sizes; bulb designations consists of a letter to indicate
its shape, and a number to indicate the diameter in eights of an inch.
•
•
•
•
Emit visible light as a result of heating; they incandesce.
They are the most familiar source of light, known as “light bulb” by the lay consumer.
Incandescent filaments can reach temperature of between 4600 and 6000 deg. F (2300K to 3000K).
Wattage of between 3 to 1000W and voltages of 6 to 277V; the 120, 125 and 130V lamps are the most
common.
Selected incandescent lamp shapes
Lamp designations of selected bulbs
Threaded or pinned bases – hold the lamp in the socket and attach the lamp to the electrical circuit
Medium base – familiar threaded base found with ordinary lamps up to 300W
Candelabra base – is smaller threaded base used in ornamental lighting such as chandeliers
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Mogul base – is a larger threaded base found on lamps that are 300W or greater.
Lamp characteristics for selected incandescent lamps. Compiled from various industry sources
The various shapes are: Standard A, Globular G, Straight S, Tubular T, Peer-shape PS, Flame F and PAR – Parabolic
aluminized reflector.
Standard A
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Globular G
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Straight S
Flame F
Tubular T
PAR-parabolic aluminized reflector
R and par lamps
Are complete optical systems in a single bulb. The bulb contains a filament, reflector and lens. R (reflector) /
BR (for bulged reflector) bulbs are lamps with “wide flood” beam angles, which means that they provide more than a
45degrees (typically 120 degrees) angle when lighting an area. Use PAR bulbs when attempting to put a focused
beam of light on an object such as in track lighting or illuminating artwork.
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Tungsten-halogen Lamps
Tungsten-halogen lamps, frequently called halogen
lamps, are a smaller, brighter, and more expensive version of
the incandescent lamp. These lamps contain high-pressure
halogen gases such as iodine or bromine, which allow the
tungsten filaments to be operated at higher temperatures and
higher efficacies.
Also called quartz or quartz-iodine lamps use a
halogen gas cycle to prevent rapid depreciation of the lamp
filament and darkening of transparent envelop. Halogen lamps
are used in automotive headlamps, under-cabinet lighting, and
work lights. In addition, halogen reflectors like MR and PAR
lamps are often preferred for directed lighting such as
spotlights and floodlights. They are also increasingly being
used as a more efficient alternative to incandescent reflectors.
Gaseous Discharge Lamps
A gaseous discharge is electricity passing through a gas such that it caused the gas to arc. It requires an
additional device called ballast. A ballast is a voltage transformer and current limiting device designed to start and
properly control the flow of power to discharge light sources such as fluorescent and HID lamps.
Low-pressure Lamps
 The gas pressure inside the discharge tube is close to vacuum (about (10 -5 of an atmosphere)
 The operating temperature is relatively low and the lamp life is relatively long.
 Examples: low pressure sodium lamps, fluorescent (low pressure mercury), neon
Low-pressure Sodium Lamp
 Low pressure sodium lamp generates light
from a discharge in sodium vapor at low
pressure (0.7 – 1 Pa)
 Great efficacy: between 150 and 200lm/W
 Made in ratings from 18 to 180W
 Lifetime of between 16000 and 23000 hours
 Monochromatic lighting producing very poor
colour rendering (<5)
Fluorescent Lamps
• Is composed of a tubular glass bulb that is covered with a thin phosphor coating on its inside surface.
• Cathodes are filament like coils at the end(s) of the bulb that act as terminals for the electric arc.
• Fluorescent lamps are available in wattages of between 20 to 125 and lengths of 6 to 96 in.
• The 120V lamps are the most commonly used fluorescent lighting in residential and light commercial
applications.
• Fluorescent lamps come in a variety of colors or temperatures such as Daylight, Cool White, Soft White,
Warm White, and Deluxe Warm White that cover the color temperature range from 3000 to 6500K
A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that
uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which
produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the lamp to glow.
Fluorescent lamps give light from a large glowing surface rather than a small intense source. These
lamps are commonly used in situations which call for general illumination at an even level such as offices,
classrooms, retail stores, hallways, and cafeterias.
While there are multiple types of LED and fluorescent tube lights, the three most common are T12,
T8, and T5. The terminology comes from “T” for “tubular” and the diameter of the bulb in eights of an inch, so
“T8” represents a tube of 8/8ths of an inch, or 1 inch.
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Linear fluorescent lamp (LFL)
Commercially available in straight, U-shaped of circular tubes in a variety of sizes, wattages, voltages,
colors, and types of bases.
Compact fluorescent lamps (CFL)
Miniaturized fluorescent lamps.
Luminaire Efficacy Rating (LER)
Is the ratio of light (the luminous flux, in
lumens) emitted by a fluorescent luminaire to the
electrical energy consumed, including the ballast.
LER = (EFF x TLL x BF)/W
High-pressure Lamps
 Gas pressure from 5kPa to greater than atmospheric pressure
 Examples: metal halide lamps, high pressure sodium lamps, high pressure mercury-vapor lamps
 Produce a very bright light by discharging an arc when electrical current passes through a metal gas
contained under high pressure in a glass bulb.
 Type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten
electrodes housed inside a translucent or transparent or transparent fused quartz or fused alumina arc tube.
 Include mercury vapor, metal halide and high-pressure sodium lamps.
 These lamps are differ from fluorescent lamps in that their gas is under high pressure, the lamp s physically
smaller, and the emitted light is more concentrated.
High-pressure Sodium Lamp
 High pressure sodium lamp (HPS) operates a pressure of 5-10kPa.
 A high pressure sodium improves the colour rendering, but decreases efficacy: 100 to 125 lm/W
depending size.
 Made in ratings from 35-1000 W
 Have a life of between 20000 and 24000 hours
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High-pressure Mercury Lamp (phases-out starting in 2015 – eco-design
regulation)
 It uses an arc through vaporized mercury in a high pressure tube to
create very bright light directly from it’s own arc.
 Made in ratings from 35-2000W
 Typical efficacy: 45 to 55lm/W
 Have a life of between 20000 and 24000 hours
High-pressure Metal Halide Lamp
 Metal Halide lamps are similar to mercury vapour lamps but use
metal halide additives inside the arc tube along with the mercury
and argon. These additives enables the lamp to produce more
visible light per watt with improved color rendition,
 Made in ratings from 35-2000W
 80-100 lumens per watt
 Have a life of between 10000 and 20000 hours
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Metal Halide Lamps
Gas Discharge Typical Performance Specification
Advantage and disadvantage of gas discharge lamps
Advantage
 Greater lifetime than incandescent halogen lamps.
 More energy efficient than incandescent lamps.
 Moderate cost, but LEDs are reaching similar prices.
 Diffused light (good for general, even lighting, reducing harsh shadows)
Disadvantage
 Contains mercury
 Needs a warm-up time to get full brightness
 Flicker of the high frequency can be irritating to humans (eye strain, headaches, migraines)
 Not the best colour rendering index (CRI)
 Not the best technology for dimming purposes
 Irritating flicker at the end of the life cycle.
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Comparison of different lamp types
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Methods of how you can maximize the amount of natural light indoors.
 Add windows
 Install tubular daylighting devices or skylights
 Think about glass doors.
Prepared by: Engr. Myrine Ysobelle S. Sioco
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