TABLE 3-6. RECOMMENDED MAXIMUM LUMINANCE RATIOS FOR
INDUSTRIAL LIGHTING Environmental Classification* B
1. Between tasks and ad- 3 to 1 3 to 1 5 to 1 jacent darker surroundings
2. Between tasks and ad- 1 to 3 1 to 3 1 to 5 jacent lighter surroundings
3. Between tasks and more 10 to 1 20 to 1 remote, darker surfaces 4 • Between tasks and more 1 to 10 1 to 20 + remote, lighter surfaces
5. Between luminaires 20 to 1 (windows, skylights, etc.)
and surfaces adjacent to them
6. Anywhere within normal 40 to 1 + field of view * Classifications are:
A Interior areas where reflectances of entire space can be controlled in line with recommendations for optimum seeing conditions.
Areas where reflectances of immediate work area can be controlled, but control of remote surroundings is limited.
Areas (indoor and outdoor) where it is completely impractical to control reflectances and difficult to alter environmental conditions.
Luminance ratio control not practical.
i. Color. Accurate color identification is required for many visual inspection tasks of aircraft and related articles (color-coded electronic wiring and tubing, paint, penetrant and nagnetic particle inspection indications, corrosion, sarety signs, etc.). The inspectors' reaction to various colors and how they feel about the area can also be important. Most characteristics of a light source can be analyzed objectively; however, color and color-rendering properties are much more subjective.
Additional information on color is provided by the IES in its handbooks on lighting.
(1) Chromaticity. Chromaticity or color temperature (whiteness) of a light source sets the tone of the space: warm (yellow, pink) or cool (blue, green). It is measured in Kelvins (K). The warmer the appearance, the lower the number; the higher the number, the bluer or cooler the color. Figure 3-8 shows the approximate color temperatures in Kelvins of several electric light sources and daylight.
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- 20000 Blue northwest sky
- 15000 Blue sky with thin white clouds Blue sky
- 10000
- 9000 7500K - 8000- high CRI fluorescents Average north sky
- 7000 - Uniform overcast sky Short-arc xenon - 6000 5000K Average noon sun high CRI fluorescents 5000 Average mixture of sun and skylight
CW & CWX fluorescent lamps
• 4000 Deluxe white mercury Warm deluxe mercury
WW & WWX fluorescent lamps 3000 - 100-watt incandescent lamp 25 watt incandescent lamp High-pressure sodium 2000 Candle flame FIGURE 3-8. CORRELATED COLOR TEMPERATURE IN KELVINS OF
SEVERAL ELECTRIC LIGHT AND DAYLIGHT SOURCES
(2) Color-Rendering. Another important quality of a light source is its ability to render the color of objects in a natural or familiar way. This is usually expressed in terms of a color-rendering index, or how well a lamp compares with a reference source of the same color temperature. The higher the number, the more nearly like the reference source. Fluorescent lamps are available in a wide range of color temperatures and color-rendering capabilities. When good color-rendering is extremely critical for inspection operations, daylight-simulating lamps are recommended. High-intensity discharge lamps trade-off, Chap 3 Page 82 Par 301
color-rendering for high efficiency and render colors in the good to poor range, however, metal halide lamps are the preferred HID source where color-rendering is important. Additional information on light source color-rendering is provided by the IES in its handbooks on lighting and in technical literature available from manufacturers of light sources.
(3) Illuminance Levels. The lighting recommendations in formance rather than for safety alone; therefore, they are not to be interpreted as requirements for regulatory minimum illuminance levels.
j. Types of Lighting Equipment. The manner in which light is controlled by the lighting equipment governs to a large extent the important effects of glare, shadows, distribution, and diffusion. Luminaires are classified in accordance with the way in which they control the light. Figure 3-9 gives the standard International Commission on Illumination (CIE) classifications for interior lighting equipment.
0-10% 10-40% 40-60% 90-100% 60-90% 40-60%
DIRECT SEMI-DIRECT GENERAL DIFFUSE 40-60% 60-90% 90-100% 40-60% 10-40% 0-10%
DIRECT-INDIRECT SEMI-INDIRECT INDIRECT FIGURE 3-9. INTERNATIONAL COMMISSION ON ILLUMINATION LUMINAIRE
CLASSIFICATIONS FOR GENERAL LIGHTING Lighting Applications. Most aircraft maintenance lighting applications call for either direct or semi-direct types of illumination. Industrial luminaires for fluorescent, highintensity discharge and incandescent filament lamps are available with upward light components which contribute to visual comfort by balance of luminances between luminaires and their back- Chap 3 Par 301 Page 83
AO 43-204 8/14/97 grounds. Figure 3-10 shows some typical lamp and fixture light distribution curves. Luminaires also require adequate shielding for visual comfort (see Figure 3-5). The shielding angle is particularly important for higher luminance sources. Good environmental luminance relationships can also often be achieved with totally direct lighting if the illuminances and room surface reflectances are high.
LAMP AND FIXTURE TYPE
HID HID FLUORESCENT HID
CANDLEPOWER DISTRIBUTION
SPACING-TO-MOUNTING-HEIGHT RATIO
0.7 1.0 1.3 1.9 FIGURE 3-10. TYPICAL LAMP AND FIXTURE LIGHT DISTRIBUTION CURVES (Courtesy of General Electric Company) Luminaires with upward components of light are preferred for most areas because an illuminated ceiling or upper structure reduces luminance ratios between luminaires and the background. The upward light reduces the dungeon effect of totally direct lighting and creates a more comfortable and more cheerful environment shown in Figure 3-11. It shows the importance of a white ceiling in an industrial facility under construction. Note the improved visual environment in the right bay (where the painters have finished the ceiling) compared with that in the left bay (as yet, unpainted). The illuminance in the right bay is also substantially higher.
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FIGURE 3-11. ILLUSTRATION OF THE IMPORTANCE OF A WHITE CEILING
FOR IMPROVING THE VISUAL ENVIRONMENT OF AN INDUSTRIAL
FACILITY (Courtesy of General Electric Company) Luminaire Top Openings. Top openings in luminaires generally minimize dirt collection on the reflector and lamp by allowing an air draft path to move dirt particles upward through the luminaire to the outer air. Therefore, ventilatec types of luminaires have proven their ability to minimize maintenance of iluorescent, high-intensity discharge, and incandescent filament types of luminaires. Gasketed dust-tight luminaires are also effective in preventing dirt collection on reflector and lamp surfaces.
(3) High Humidity or Corrosive Atmosphere and Classified (Hazardous) Location Lighting. The National Fire Protection Association (NFPA) is phasing out the word "Hazardous" for the word "Classified."
Nonclassified Areas. Enclosed gasketed luminaires are used in nonclassified areas where atmospheres contain nonflammable dusts and vapors or excessive Enclosures protect the interior of the luminaire from conditions prevailing in the area.
Severe corrosive conditions necessitate knowledge of the atmospheric content to permit selection of proper material for the luminaire.
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AC 43 - 204 8/14/97
• Classified Areas. Classified locations are areas where atmospheres contain inflammable dusts, vapors, or gases in explosive concentrations.
are grouped by the National Electrical code on the basis of their hazardous characteristics, and all electrical equipment should be approved for use in specific classes and groups. Luminaires are available, specifically designed to operate in these areas, which are noted in Article 500 of the National Electrical Code as Class I, Class II, and Class III locations. Luminaires used in these areas are designated as: explosion-proof, dusttight, dust-proof, and enclosed and gasketed.
Other Factors. In selecting industrial lighting equipment, the following other factors lead to more comfortable Lighting installations:
• Light-colored finishes on the outside of luminaires to reduce luminance ratios between the outside of the luminaire and the inner reflecting surface and light source.
• Higher mounting heights to raise luminaires out of the normal field of view.
• Better shielding of the light source by deeper reflectors, cross baffles, or louvers. This is particularly important with high-wattage incandescent filament or high-intensity discharge sources and the higher output fluorescent lamps.
• Selecting light control material, such as mirrored or nonmirrored aluminum, prismatic configured glass, or plastic that can limit the luminaire luminance in the shielded zone.
k. Supplementary Lighting. Difficult seeing tasks often require a specific amount or quality of lighting which cannot readily be obtained by general lighting methods. Supplementary luminaires are often used to solve such problems by providing higher illuminances for small or restricted areas. Supplementary luminaires are also used to furnish a certain luminance, color, or to permit special aiming or positioning of light sources to produce or avoid highlights or shadows to best portray the details of the task. Figure 3-12 shows examples of placement of supplementary luminaires.
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e Examples of placement of supplementary luminaires: a. Luminaire located to prevent vailing reflections and reflected glare; reflected light does not coincide with angle of view. b. Reflected light coincides with angle of view. c. Low-angle lighting to emphasize surface irregularities. d. Largearea surface source and patter are reflected toward the eye. e. Transillumination from diffuse sourco.
FIGURE 3-12. EXAMPLES OF PLACEMENT OF SUPPLEMENTARY LUMINAIRES
(1) Nature of Visual Task. Before supplementary lighting can be specified, it is necessary to recognize the exact nature of the visual task and to understand its light reflecting or transmitting characteristics. An improvement in the visibility of the task will depend upon one or more of the four fundamental visibility factors: luminance, contrast, size, and time. Theretore, in analyzing a visual task, it may be found that seeing difficulty is caused by insufficient luminance, poor contrast (veiling reflections), small size, or that the task motion is toc fast for existing seeing conditions.
(2) Planning of Supplementary Lighting. The planning of supplementary lighting also entails consideration of the visual comfort of both those workers who benefit directly and those who are in the immediate area. Supplementary equipment should be carefully shielded to prevent glare for the users and their associates. Luminance ratios should be carefully controlled. Ratios between task and immediate surroundings should be limited as recommended in Table 3-5. To attain these limits it is necessary to coordinate the placement of supplementary and general lighting.
Luminaires for Supplementary Lighting. The IES divides supplementary lighting units into five major types according to candlepower distribution and luminance as follows:
• Type S-I-Directional: Includes all concentrating units. Examples are a reflector spot lamp or units employing concentrating reflectors or lenses. Also included in the group are concentrating longitudinal units, such as a wellshielded fluorescent lamp in a concentrating re- Chap 3 Par 301 Page 81
• Type S-II-Spread, High Luminance: Includes smallarea sources, such as incandescent or highintensity discharge. An open-bottom, deep-bowl diffusing reflector with a high-intensity discharge lamp is an example of this type.
• Type S-III-Spread, Moderate Luminance: Includes all fluorescent units having a variation in luminance greater than two-to-one.
• Type S-IV, Uniform Luminance: Includes all units having less than two-to-one variation of luminance. Usually this luminance is less than 640 candelas per square foot. An example of this type is an arrangement of lamps behind a diffusing panel.
• Type S-V, Uniform Luminance With Pattern: A luminaire similar to Type S-IV, except that a pattern of stripes or lines is superimposed.
Portable Luminaires. Whenever possible, supplementary luminaires should be permanently mounted in the location to produce the best lighting effect. Adjustable arms and swivels will often adapt the luminaires to required flexibility. Portable equipment (see Table 3-7), however, can be used to good advantage where it should be moved in and around movable machines or ob- Jects, such as in airplanes, or where internal surfaces should be viewed. The luminaires should be mechanically and electrically rugged to withstand possible rough handling. Lamps should be guarded and of the rough-service type. Guards or other means should protect the user from excessive heat. Precautions should be taken to prevent electrical shock. Cords should be rugged and insulation should conform to environmental requirements.
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TABLE 3-7. TYPICAL PORTABLE LUMINAIRES FOR SUPPLEMENTARY LIGHTING (Sheet 1 of 7) (Courtesy of McMaster-Carr Supply Company)
ADJUSTABLE ARM LIGHTS
a. Gooseneck Lights. These lights have an adjustable gooseneck and are available with high-intensity or standard incandescent lamps. They are also available with magnetic base, table base, C-clamp mount, and explosion-proof housings. They operate on 120V AC.
b. Floating Arm Lights. These lights are available with high-intensity fluorescent or standard incandescent lamps and have a floating arm that is adjustable by lightly touching with a finger. They are also available with magnetic base, caster base, weighted base, table base, universal mount, and waterproof or explosion-proof housings.
They operate on 120V AC.
c. Adjustable High-Intensity Lights. This has a five-position switch that provides varying light intensities. The arm has an 18-inch reach and swivels 360° horizontally and vertically, eliminating wire twist. It operates on 120V AC.
d. Clip-On Lights. These lights are available with high intensity or standard incandescent lamps and have a spring-loaded clip to attach practically anywhere.
Lights have an adjustable shade to allow directing of light beam. They operate on 120V AC.
PORTABLE UTILITY LIGHTS Caddy-Mounted and Tripod-Base Lights.
Caddy-mounted and tripod-base lights are available with standard incandescent, fluo- apar rescent and high-intensity lamps. They operate on 120V AC.
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TABLE 3-7. TYPICAL PORTABLE LUMINAIRES FOR SUPPLEMENTARY LIGHTING (Sheet 2 of 7) (Courtesy of McMaster-Carr Supply Company) PORTABLE UTILITY LIGHTS (Continued)
b. Self-Powered Flood Lights. Selfpowered lights are available with gasoline or diesel engines and metal malide or highpressure sodium lamps. They have a telescoping base that is adjusted with a winch and two semi-pneumatic tires. They are available with 120- and/or 240-V AC outlets.
High Pressure Sodium Light Cart. The light cart produces high-intensity lighting with a wide-angle beam. The light has a tempered glass lens with a wire guard and the cart has two 10-inch wheels and a heavy-gauge steel frame with a handle for easy portability. The cart operates on 120V AC.
d. Polygon Quartz Halogen Floodlights. A polygon-shaped frame can be positioned on any of five sides to aim the light beam where it is needed. A halogen lamp is suspended between springs for maximum impact and vibration resistance. It operates on 120V AC and is UL listed for wet locations inside and outdoors.
fights have up to 500 wạtts of high- intensity illumination in rugged easy to High-Intensity Floodlights. These carry units with fixed or bolted-down swivel base. They operate on 120V AC.
£ . Explosive-Proof Floodlight. This floodlight has a cast aluminum housing with a heat and impact-resistant glass lens.
The light moves 135° vertically in a yoke and the base swivels 360° and can be bolted down, It uses incandescent medium-base spot or flood lamps and also accepts reflector spot or flood lamps. It operates on a maximum of 600V AC and it is UL standard 844 listed Class I Groups C and D for 150- watt lamps and Class I, Group B for 300- watt lamps.
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TABLE 3-7. TYPICAL PORTABLE LUMINAIRES FOR SUPPLEMENTARY LIGHTING (Sheet 3 of 7) (Courtesy of McMaster-Carr Supply Company) PORTABLE UTILITY LIGHTS (Continued) Fioodlight Corrosion-Resistant Floodlights. is suitable for use in damp, This corrosive conditions. The fixture has a protective wire guard, a locking base, and a plastic carrying handle. It operates on 120V AC and UL listed.
INCANDESCENT TROUBLE LIGHTS General-Purpose Trouble Light. These general purpose heavy duty lights use 100- watt incandescent lamps. They operate on 120V AC, meet OSHA specifications and are UL listed.
Rights are available with a tempered glass or plastic globe that screws into the han- Vapor-Proof Trouble Lights. These dle to form a vapor-proof seal. They use a 100-watt lamp and operate on 120V AC. They are UL listed for enclosed and gasketed fixtures and meet OSHA and National Electrical Code (NEC) requirements.
c. Flood and Spot Trouble Light. This light uses a flood or spot lamp and has a welded metal guard. This trouble light operates on 120V AC, meets OSHA specifications, is UL listed and CSA approved.
d. Magnetic Base Trouble Lights. These trouble lights can be hung by a swivel hook or attached to a ferrous surface with a magnet built into the handle base. They operate on 120V AC, use a 75-watt bulb and are UL listed.
Hazardous Location Trouble Light.
trouble light is spark and weather tant with an aluminum guard and swivel listed for Standard A21 incandescent It operates on 120 volts AC.
to 100 watts and Class II, Group G using a 75-watt A21 lamp.
Coiled Cord Trouble Light.
ble light has a coiled cord that resists kinks and knots. The 75-watt light operated on 125V AC. meets OSHA specifications for general use and is UL listed.
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TABLE 3-7. TYPICAL PORTABLE LUMINAIRES FOR SUPPLEMENTARY LIGHTING (Sheet 4 of 7) (Courtesy of McMaster-Carr Supply Company) INCANDESCENT TROUBLE LIGHTS (Continued) Trim-Line Nonconductive Trouble Light.
This light is completely insulated and won't spark. The light has a flexible, oilproof rubber handle and a tubular nylon guard. The light uses a 7C7 7-watt incandescent lamp and operates on 120V AC.
FLUORESCENT TROUBLE LIGHTS
a. Watertight Trouble Lights. These lights have a butyrate shield and neoprene rubber end cap and handle seal to keep out water and dampness. They have hinged hooks on the end cap and handle that allow them to be easily positioned in the work area.
They are available with 20-watt or 40-watt T-12 fluorescent lamps, operate on 120-V AC and are FM approved.
fight slips into hard-to-reach, hard-to- Coiled Cord Trouble Light. This small light places. It has a coiled tangle resistant cord that extends up to 13 feet.
butyrate shield protects the lamp from direct contact. It is available with 6-watt and 8-watt T-5 fluorescent lamps.
ates on 120V AC and is FM approved.
fiuorescent light can be stuck to ferrous surfaces and has an arm and adjustable Magnetic Base trouble Light.
bracket for quick secure positioning. It has an 8-watt lamp protected by a shatterproof plastic tube. It operates on 120V AC and is UL listed.
₫. Compact Trouble Light. The 4-watt model has no exposed metal beyond the ballast; 8-watt model has a grounded metal reflector. It is available with a magnetic holder. Lights come with an 18-foot SJ cord and plug. The diameter is 1 5/16 inches and the length is from 10 inches (4 watt) to 15 inches (8 watt). It operates on 120V AC.
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