Lighting Reference Guide – Fluorescent Lamps

9 Fluorescent Lamps

a. General

Construction

  • For typical construction of a fluorescent lamp, see the figure below.
  • A fluorescent lamp is a low–pressure mercury electric discharge lamp.
  • A fluorescent lamp consists of a glass tube filled with a mixture of argon gas and mercury vapour at low pressure.
  • When current flows through the ionized gas between the electrodes, it emits ultraviolet (UV) radiation from the mercury arc.
  • The UV radiation is converted to visible light by a fluorescent coating on the inside of the tube.
  • The lamp is connected to the power source through a ballast, which provides the necessary starting voltage and operating current.

Typical Construction of a Linear Fluorescent Lamp

Typical Construction of a Linear Fluorescent Lamp

Basic Types of Fluorescent Lamps

  • Preheat lamps
  • Instant start lamps
  • Rapid start lamps

Preheat Lamps

  • The cathodes of the lamp are preheated electrically for a few seconds before a high voltage is applied to start the lamp.
  • The preheating is accomplished by the use of an automatic switch, called a “starter”, which applies current to the cathodes for sufficient time to heat them.
  • The preheat lamps have a bi–pin (double–pin) base at each end.
  • Preheat lamps operate normally in a preheat circuit (preheat ballast, starter, lamp and lamp holders).
  • Preheat lamps can also be used in rapid start circuits.
  • Preheat lamps are not widely used today

Instant Start Lamps

  • The instant start lamp requires a high starting voltage, which is supplied by the ballast.
  • Since there is no preheating of the cathodes, there is no need for a starter.
  • Electrode heating is provided by the arc once it has been established.
  • The instant start lamps have a single–pin base at each end of the bulb.
  • A few instant start lamps have bi–pin bases, with the pins connected together inside the base.
  • Instant start lamps operate normally only in an instant start circuit (instant start ballast, lamp and lamp holders).

Rapid Start Lamps

  • The ballast quickly heats the cathodes causing sufficient ionization in the lamp for the arc to strike.
  • The cathodes may or may not be continuously heated after lamp starting, depending on ballast design.
  • Rapid start lamps start almost instantly (in one or two seconds).
  • No starter is required – eliminating the time delay of preheat systems.
  • Less voltage is required for starting than with instant start lamps, thus using smaller, more efficient ballasts.
  • The rapid start lamps have a bi–pin (double–pin) base at each end.
  • Rapid start lamps can also be used for dimming and flashing applications.
  • Rapid start lamps operate normally only in a rapid start circuit (rapid start ballast, lamp, and lamp holders).
  • Rapid start lamps are the most widely used fluorescent lamps.

Types of Rapid Start Lamps

  • Linear fluorescent lamps – new types, both T8 and T5 sizes
  • Linear fluorescents (430 mA for F40) – old types, primarily T12 size
  • Energy saving fluorescents, primarily T12 size
  • U–shaped fluorescents, in both T8 and T12 sizes
  • Circular lamps, in T9 and T5 sizes
  • High output lamps, available in T12, T8 and T5 sizes
  • Very high output lamps (1500 mA), primarily T12 size
  • Lamp diameters range from 5/8” to 2.5”

Shapes

Shapes

Lamp Designations

Bi–pin lamps (preheat, instant start, rapid start)

Identified by wattage, bulb diameter and colour.
 
Example: F40TI2/CW/ES
 
  F : Fluorescent lamp
  40 : Wattage (34 W for ES types)
  T : Tubular bulb shape
  12 : Maximum tube diameter – in eighths of an inch (12/8 = 1.5”)
  CW : Cool white colour
 
Example: F32 T8/41K
 
  F : Fluorescent lamp
  32 : Wattage (32 W)
  T : Tubular bulb shape
  8 : Maximum tube diameter – in eighths of an inch (8 x 1/8 = 1”)
  41K : 4,100 K, Cool white colour
 
Single–pin lamps (instant start)

Identified by length and colour rather than wattage because they can operate at more than one wattage.
 
Example: F96T12/WW
 
  F : Fluorescent lamp
  96 : Lamp length in inches
  T : Tubular bulb shape
  12 : Maximum tube diameter – in eighths of an inch
  WW : Warm white colour
 

Lamp Lengths

Some typical lamp lengths are:

  • F20 lamp – 24” ( 2' )
  • F30 lamp – 36” ( 3' )
  • F32 T8 lamp – 48” ( 4' ) – becoming the industry standard lamp
  • F40 lamp – 48” ( 4' )
  • F96 lamp – 96” ( 8' )

Colour Codes

(e.g., 841 = 80% CRI and 4100 Kelvin)

    CRI CTT
(Kelvin)
       
C50 : Chroma. 50 (5,000K, CR190+) 90+ 5000
C75 : Chroma 75 (7,500K, CR190+) 90+ 7500
CW : Cool White 62 4200
CWX : Cool White Deluxe 87 4100
D : Daylight 76 6500
LW : Lite White 48 4150
N : Natural 86 3600
SP : Spectrum Series 70+ varies
SPX : Spectrum Series Deluxe 80+ varies
WW : Warm White 52 3000
WWX : Warm White Deluxe 74 2950
741 : T8 Cool lamp colour 70+ 4100
735 : T8 Neutral lamp colour 70+ 3500
730 : T8 Warm lamp colour 70+ 3000
841 : T5 & T8 Cool lamp colour 85+ 4100
835 : T5 & T8 Neutral lamp colour 85+ 3500
830 : T5 & T8 Warm lamp colour 85+ 3000
Deluxe : Means better CRI, but with older style T12 lamps, also lower efficacy

Lamp Type Code

The lamp type code follows the colour code.

Lamp type codes are listed below.

  IS :  Instant Start
 
  RS :  Rapid Start
 
  HO :  High Output
 
  VHO :  Very High Output
 
  U :  U–shaped
 
  WM :   WattMiser (General Electric)
 
  SS :  Super Saver
 
  EW :  Econowatt (Philips)

Characteristics

General   –  A fluorescent luminare consists of:
    a ballast, usually shared by two lamps, fixture and
    lense or louvers
 
Lamp Configuration
 		 –  Linear, U–shape, circular or compact
 
Lamp Watts –  7 W to 215 W
 
Ballast Watts –  Varies according to type, electromagnetic
    or electronic, and Ballast Factor
 
Rated Average Life –  20,000 hours for typical F32T8 lamps
–  24,000 hour T8 lamps are available
–  20–24 times the life of a typical incandescent
 
Luminous Efficacy –  40 to 100 lumens per watt
 
Lamp Lumen –  70% to 90%
 

Depreciation Factor (LLD)
 
Colour Temperature –  2,700 K to 7,500 K
–  Wide range of colour temperatures
Index (CRI)
 
Colour Rendering –  62 to 94
 
Warm–up Time –  Instant
–  Sensitive to extremes of temperature
–  Slower than incandescent
 
Restrike Time –  Immediate
 
Lamp Cost
 		 –  Low
–  Energy–saving and energy–efficient lamps
    more expensive
 
Main Applications –  Offices, commercial
 
Lamp
Designation		 Lamp
Watts		 Including
1 Lamp		 Ballast
(2 Lamp)		 Rated
Lamp
Life
(hours)		 Initial
Lumens		 Initial
Lumens
per
Watt		 Colour
Temp
Deg
K		 CRI
Energy Saving, Rapid Start, Bi–Pin Base        
F4OT12/.... /RS/....EW, SS or WM        
CW 34 47 (81) 20,000 2,775 59.0 4,100 62
CWX 34 47 (81) 20,000 1,925 41.0 4,100 87
WW 34 47 (81) 20,000 2,825 60.1 3,000 52
D 34 47 (81) 20,000 2,350 50.0 6,500 75
LW 34 47 (81) 20,000 2,925 62.2 4,160 48
3OU 34 47 (81) 20,000 2,925 62.2 3,000 85
35U 34 47 (81) 20,000 2,925 62.2 3,500 85
41U 34 47 (81) 20,000 2,925 62.2 4,100 85
5OU 34 47 (81) 20,000 2,925 62.2 5,000 85
SPEC30 34 47 (81) 20,000 2,925 62.2 3,000 70
SPEC35 34 47 (81) 20,000 2,925 62.2 3,500 73
SPEC41 34 47 (81) 20,000 2,925 62.2 4,100 70
Notes: • Refer to lamp manufacturers for colours other than shown here.
• Rated Average Life for fluorescent lamps is based on three hours per start.
• Mean Lumens for fluorescent lamps are listed at 40% of lamp life.
 
See also: • Lamp manufacturers' catalogues.
Lamp
Designation		 Lamp  
Watts  		 Including
Ballast
1 Lamp
(2 Lamps)		 Rated
Lamp
Life
(hrs)		 Initial
Lumens		 Initial
Lumens
per
Watt  		 Mean
Lumens		 Mean
Lumens
per
Watt		 Colour
Temp
Deg
K		 CRI    LLD
Compact Fluorescent
7W + 7   10         10,000 400 40.0     2,700 81 0.80
9W + 9   10         10,000 600 60.0     2,700 81 0.80
13W + 13   17         10,000 900 52.9     2,700 81 0.80
Circlite (retrofit for incandescent)
FCA22/SW + 22   22           10,000 870 39.5        
FCA44/SW + 44   44           7,500 1,750 39.8        
Rapid Start Circline
FC8/CW/RS + 1 22   27         12.000 1,050 38.9 805 29.8 4,300 62 0.72
FC12/CW/RS + 32   44         12,000 1,800 40.9 1,465 33.3 4,300 62 0.82
FC16/CW/RS + 40   56         12,000 2,500 44.6 1,910 34.1 4,300 62 0.77
Instant Start, 200 milliamp, Single Pin Base
F72T8/CW 38   55 (100) 7,500 3,100 56.4 2,700 49.1 4,300 62 0.83
F96T8/CW 50   70 (130) 7,500 4,200 60.0 3,860 55.1 4,300 62 0.89
Instant Start, 430 milliamp, Single Pin Base
F48Tl2/CW 39   65 (104) 9,000 3,000 46.2 2,760 42.5 4,300 62 0.82
F48TI2/LW 30   55  (84) 9,000 2,675 48.6 2,460 44.7 4,100 49 0.82
F72Tl2/CW 55   80 (150) 12,000 4,600 57.5 4,320 52.9 4,300 62 0.89
F96T12/CW 75   97 (172) 12,000 6,300 64.9 5,800 59.8 4,300 49 0.89
F96TI2/LW 60   82 (142) 12,000 6,000 73.2 5,430 66.2 4,100 49 0.89
Rapid Start, 430 milliamp, Bi–pin Base
F30T12/CW/RS 30   46 (76) 18,000 2,300 50.0 2,010 43.7 4,300 62 0.81
F4OTl2/.../RS                    
cool white 40   53 (93) 20,000 3,150 59.4 2.715 51.2 4,300 62 0.84
cool while deluxe 40   53 (93) 20,000 2,220 41.5 1,800 34.0 4,200 87 0.84
warm white 40   53 (93) 20,000 3,200 60.4 2,715 51.2 3,000 52 0.84
warm white deluxe 40   53 (93) 20,000 2,150 40.6 1,765 33.3 3,100 73 0.84
daylight 40   53 (93) 20,000 2,600 49.1 2,245 42.4 6,500 75 0.84
lite white 35   48 (83) 20,000 3,050 63.5     4,160 48 0.84
lite white deluxe 34   47 (81) 20,000 3.050 64.9     4,100 67 0.84
full spectrum 5000 40   53 (93) 20,000 2,200 41.5 1,850 34.9 5.000 92 0.84
full spectrum 7500 40   53 (93) 20,000 2,000 37.7 1,685 31.8 7,500 94 0.84
prime colour 3000 40   53 (93) 20,000 3,400 64.2     3,000 85 0.84
prime colour 4000 40   53 (93) 20,000 3,400 64.2     4,000 85 0.84
*indicates low power factor ballast only available
Rapid Start T8, Bi–pin Base
F032/730 32   30 (59) 20,000 2,800 93.0 2,520 84.0 3,000 75 0.90
F032/830 32   30 (59) 20,000 2,950 98.0 2,714 90.0 3,000 82 0.92
F032/830 6   30 (59) 24,000 2,900 96.6 2,755 91.8 3,000 85 0.95
F032/830/XP   30 (59) 24,000 3,000  100 2,850 95.0 3,000 85 0.95
Hiqh Output Rapid Start, 800 milliamp, Recessed Double Contact Base
F48TI2/CW/HO 60   85 (146) 12,000 4,300 50.6 3,740 44.0 4,300 62 0.82
F72Tl2/CW/HO 85   106(200) 12,000 6,650 62.7 5,785 54.6 4,300 62 0.82
F96Tl2/CW/HO 110   140(252) 12,000 9,200 65.7 8,005 57.2 4,300 62 0.82
F96TI2/LW/HO 95   119(231) 12,000 9,100 76.5 7,915 66.5 4,160 48 0.82
F96Tl2/LWX/HO 95   119(231) 12,000 9,100 76.5     4,100 67 0.82
Very High Output Rapid Start, 1500 milliamp, Recessed Double Contact Base
F48TI2/CW/VHO 110   146(252) 10,000 6,250 42.8 4,750 32.5 4,300 62 0.69
F72Tl2/CW/VHO 165   213(326) 10,000 9,900 46.5 7,920 37.2 4,300 62 0.72
F96Tl2/CW/VHO 215   260(450) 10,000 14,500 55.8 11,600 44.6 4,300 62 0.72
F96PG17/CW 215   260(450) 12,000 16,000 61.5 12,800 49.2 4,300 62 0.69
F96PG17/LW 185   230(390) 12,000 14,900 64.8 11,325 49.2 4,160 48 0.69
* indicates low power factor ballast only available.
Notes: Some lamps listed here are no longer commercially available, notably the full output F40/CW lamp; they are included here for comparison only.
 

b. Premium T–8 Lamps

Lamp manufacturers now offer premium grade T–8 lamps for special applications where exceptional colour, longer life and improved lumen output are required.

Standard F32 T–8 Lamp: 20,000 hrs, 82 CRI, 2,950 initial lumens,
98.3 initial lm/W
 
Premium F32 T–8 Lamp: 30,000 hrs, 86 CRI, 3,100 initial lumens,
103.3 initial lm/W
 

c. Low–Wattage T–8 Lamps

Lamp manufacturers now offer reduced output or low–wattage T–8 lamps for increased savings on retrofit projects, or for new construction.

Standard F32 T–8 Lamp: 20,000 hrs, 82 CRI, 2,950 initial lumens,
up to 80 lm/W depending on ballast
 
Low–Wattage F28 T–8 Lamp: 324,000 hrs, 82 CRI, 2,562 initial lumens,
up to 93 lm/W, depending on ballast
  • These lamps have some limitations, for example, they cannot be dimmed, and don't operate in cool temperatures (<60°F)
  • Some operate on programmed start ballasts and all operate in instant start ballasts.

d. T–5 and T5–HO Fluorescent Lamps

  • Lamp manufacturers now offer T–5 fluorescent lamps in both standard and High Output (HO) versions.
  • The smaller diameter tube yields a more compact lumen package, which is easier to control.
  • T–5 fluorescent lamps are available in various lengths and wattages from 14 W to 80 W, and in a circline version in 22 W, 40 W, and 55 W.
  • T–5 lamps are nominal length lamps, which means that they cannot be retrofit into fixtures using standard T–12 or T–8 lamps. Therefore, they are generally used for re–design or new construction projects.
  • T–5 fluorescent lamps require the use of electronic ballasts and unique sockets.
  • T–5 lamps are driving miniaturization and can be used in indirect applications.
  • T5–HO is an increasingly popular fluorescent lamp; primarily used in normal to high bay applications, big box retail, warehouse and distribution centres, industrial applications and gymnasiums. T5–HO are also dimmable and operate on instant start ballasts.
  • T5 and T5–HO have maximum light output at higher ambient temperatures.
Standard T–5 Lamps: 14 W, 24” (nom), 20,000 hrs, 82 CRI,
1,350 initial lumens
 
  21 W, 36” (nom), 20,000 hrs, 82 CRI,
2,100 initial lumens
 
  28 W, 48” (nom), 20,000 hrs, 82 CRI,
2,900 initial lumens
 
  35 W, 60” (nom), 20,000 hrs, 82 CRI,
3,650 initial lumens
 
High Output T–5 Lamps: 24 W, 24” (nom), 20,000 hrs, 82 CRI,
2,000 initial lumens
 
  39 W, 36” (nom), 20,000 hrs, 82 CRI,
3,500 initial lumens
 		  
  54 W, 48” (nom), 20,000 hrs, 82 CRI,
5,000 initial lumens
 

e. Fluorescent Fixture Reflectors

General Description

Fluorescent fixture reflectors are sheets of aluminum placed inside fluorescent fixtures, which divert light directed toward the ceiling down toward the work area.

Illustration

  • Illustration of a recessed reflector for a 2 x 4' fixture, with removal of two lamps.

Before installation of the reflector:

Before installation of the reflector

After installation of the reflector:

After installation of the reflector

Physical Data

  • There are three basic types of reflectors:
     
  • Anodized aluminum or steel reflectors – in which the surface is painted with a highly reflective electrostatic or powder–epoxy finish.
  • Anodized aluminum reflectors – in which the aluminum surface is treated (polished) electrochemically.
  • Silver film reflectors – in which a thin film of silver is laminated to an aluminum substrate.
     
  • The reflector finish can be high gloss paint, specular (mirror–like), semi–specular, or diffuse (matt).
  • The reflector shape is specially designed to optimize light distribution (custom–designed by the supplier).
  • Reflectors are made in the following sizes:
     
  • Single reflectors – 4' or 8' long, one–lamp use
  • Double reflectors – 4' or 8' long, two–lamp use
  • Recessed reflectors – for 2' x 2' or 2' x 4' fixtures.

Technical Data

  • The average total reflectivity for anodized aluminum reflectors is about 90% to 91%.
  • The average total reflectivity for silver film reflectors is about 94% to 97%.
  • Life expectancy of a silver film reflector is about 15 years.
  • Life expectancy of an anodized aluminum reflector is about 20 years.

Applications

  • Reflectors are used for lighting energy conservation.
  • Reflectors are used for fixture retrofitting or in new energy efficient fixtures.
  • A typical application is the installation of a recessed reflector in
    a 2' x 4' fixture, with removal of two of the four tubes.
  • In most instances, it is necessary to re–centre the two remaining lamps in the fixture to avoid dark spots.
  • The reflector creates the image of a lamp in the place of the removed lamp; this allows delamping without creating dark spots.
  • The light output of a retrofitted fixture with half the lamps removed typically decreases by about 35%, depending on reflector material and design.
  • Cleaning and relamping at the same time increases light output by 5% to 20%.

Costs

  • Costs depend on the type, size and design of the reflector.

Advantages

  • Reduces lighting power consumption;
  • Improves luminous efficacy in the work area;
  • Reduces cooling load, in the case of delamping;
  • Extends ballast and lamp life by decreasing operating temperature;
  • Fewer lamps and fixtures are required;
  • Reduces maintenance costs.

Disadvantages

  • May have long payback period;
  • Not cost–effective if fixtures of different size and type are involved;
  • May create a ‘cave effect’ in some situations, causing walls to appear dark at the top because the light is focused downwards.

Assessment

  • Has clear benefits from a lighting efficiency point of view.
  • Should be compared to other lighting conservation measures.

f. Compact Fluorescent Lamps

Introduction

  • Compact fluorescent lamps are small–size fluorescent lamps.

Types

  • There are two general types of lamps:
     
  • self–ballasted or screw based lamps, for direct replacement of incandescent lamps
  • pin–based lamps for compact fluorescent light fixtures
     
  • They are also available in a large variety of sizes and wattages, and in twin–tube, quad–tube, long tube, twisted, reflectorized and fully enclosed versions.
lamp type

Fluorescent Lamps

Fluorescent Lamps

Shapes

Lamp Magnetic
Ballast
System
Watts		  Lumens Lumens
per
Watt		 Length
(mm)		 Length
(in.)		 Colour
Temp K		  CRI Life Base
2–tube or Bi–tube
5 W 8 W 250 50 105 4 1/8 2700 82 10,000 G23
7 W 10 W 400 57 135 5 5/16 2700 82 10,000 G23
9 W 12 W 600 67 167 6 9/16 2700 82 10,000 G23
13 W 17 W 900 69 178 7 1/2 2700 82 10,000 G23
4–tube or Quad–tube
10 W 14 W 600 60 108 4 1/4 2700 82 10,000 G24D–1
13 W 17 W 900 69 140 5 5/8 2700 82 10,000 G24D–1
18 W 23 W 1,250 69 170 6 7/8 2700 82 10,000 G24D–2
26 W 32 W 1,800 69 190 7 1/2 2700 82 10,000 G24D–3
Long–tube or High Output
18 W 25 W 1,250 69 221 8 11/16 2700 82 10,000 2G11
            3000 82 10,000 2G11
            4000 82 10,000 2G11
24 W 32 W 1,900 79 320 12 9/16 2700 82 10,000 2G11
            3000 82 10,000 2G11
            4000 82 10,000 2G11
36 W 48 W 3,000 83 417 16 7/8 2700 82 10,000 2G11
            3000 82 10,000 2G11
            4000 82 10,000 2G11

Self–ballasted Types

Lamp Watts Lumens Lumens
per
Watt		 Life To
Replace
CF7EL 7 280 40    6 000 hrs 25 W chandelier lamp
CF14EL 14 800 57.1 6 000 hrs 60 W A lamp
CF15EL/G 15 700 46.7 6 000 hrs 60 W G lamp
CF20EL 20 1,200 60    6 000 hrs 75 W A lamp
CF20EL/R 20 875 43.8 6 000 hrs 70 W ER lamp
CF23EL 23 1,450 63    6 000 hrs 100 W A lamp

General Remarks

  • The self–ballasted (screw base) lamps are available with incandescent–like features (small size, shape, dimming, 3–way, etc.)
  • Compact fluorescent lamps are about four times more efficient than standard incandescent lamps.
  • Efficacy or lamp efficiency increases with lamp size and wattage. The smaller size, lower wattage lamps are generally less efficient than the larger size and higher wattage lamps.
  • Compact fluorescents have an average life that is 10 times longer than that of standard incandescent lamps, and have a lower maintenance costs.
  • They have a high colour rendering index, generally >82, but lower than incandescent lamps.
  • They need a ballast to operate, as do all fluorescent lamps.
  • Lamps of different manufacturers are interchangeable.
  • Maximum overall length.
  • Most compact fluorescent lamps are available with a variety of colour temperature values, similar to T5 and T8 fluorescent lamps (3,000 K, 3,500 K, 4,100 K).
  • There is an ENERGY STAR® program for compact fluorescent lamps in North America.

Compact Fluorescent Fixtures

  • Many manufacturers produce fixtures for compact fluorescent lamps which include a specially designed ballast and socket (lamp holder). These are available in recessed, outdoor and decorative versions.
  • Lamp manufacturers produce retrofit adapters which include the ballast and lamp socket, and have a base to screw directly into a standard incandescent socket (see Self–Ballasted Types, above.).
  • Recessed compact fluorescent fixtures should have a properly designed reflector, otherwise light will be trapped inside the fixtures and be wasted.

Two–tube Compact Fluorescent Lamps

  • Can be used as replacements for small incandescent lamps.
  • Compact fluorescent lamp sizes 5 W, 7 W, 9 W and 13 W can replace incandescent lamp sizes 25 W, 40 W, 50 W and 60 W respectively.
  • Compact fluorescent lamps of different wattage rating use slightly different bases and sockets, to eliminate the possibility of plugging a lamp into a fixture with the wrong ballast for that lamp. For example, it is not possible to plug a 13 W lamp into the socket of a fixture with a ballast rated for a 26 W lamp.

Applications

  • Lobby areas, hallways and corridors, any area where there are long hours of use.
  • Recessed downlight fixtures.
  • Wall and ceiling–mounted fixtures.
  • Directional signs.
  • Security lighting fixtures.
  • Desk and task lighting fixtures.
  • Display lighting (museums, stores).
  • To replace light bulbs in fixtures which are not readily accessible.

Four–Tube Compact Fluorescent Lamps

  • Made by combining two two–tube compact fluorescent lamps.
  • Also known as double twin–tubes, quad or cluster lamps.
  • Same length as two–tube compacts, but double the light output (lumens).
  • Four–tube compact fluorescent lamp sizes 9 W, 13 W, 22 W and 28 W can replace incandescent lamp sizes 40 W, 60 W, 75 W and 100 W respectively.

Applications

  • Similar to the applications of the two–tube compact fluorescent lamp (see above).
  • The four–tube compact fluorescent lamps replace relatively higher wattage incandescent lamps than the two–tube compacts.

Long Tube Compact Fluorescent Lamps

  • Longer than the two–tube and four–tube compact fluorescent lamps.
  • Can replace standard fluorescent lamps.
  • Long tube compact fluorescent lamp sizes 18 W, 24 W and 36 W have the same light output as standard fluorescents F20, F30 and F40 respectively, but are only one third of the length.
  • Longer compact fluorescent lamps also feature longer lamp life, up to 20,000 hrs.

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