Accent lighting is used to emphasize areas of a room or individual objects. Very bright accents work well. The level of accent lighting is higher than that of the general lighting.
Our eyes take time to adapt to fluctuations in brightness. How they adapt and how long it takes depends on the levels of luminance before and after the brightness changes. Adapting to brighter conditions takes only a matter of seconds; adapting to darkness can take minutes. The adaptation process impacts on visual performance.
ASR Workplace Regulations
Lighting designed to suit working conditions is a fundamental requirement for the prevention of accidents. In Germany, workplace lighting is thus governed by a Workplace Decree (Arbeitsstättenverordnung) and a number of implementing regulations (ASR workplace regulations) for different applications. ASR 7/3 applies to workplaces in buildings.
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Discharge lamps - e.g. fluorescent lamps - need to be operated with a ballast. This is because ignition is followed by massive ionisation of the inert gas or metal vapour in the lamp, which causes a surge in current in the lamp. This would destroy the lamp within a short time, so a ballast is used to limit the lamp current (also during operation). A distinction needs to be made between conventional ballasts (CB), low-loss ballasts (LB) and electronic ballasts (EB). EBs for fluorescent lamps are available in dimmable and non-dimmable designs. In energy-saving lamps, ballasts are integrated into the screw base; otherwise they form part of the luminaire.
Basic lighting - also referred to as general lighting - is the uniform room lighting which takes no special account of visual tasks performed at different points in the room. It makes sure that architecture, objects and people in the room are visible and permits orientation. Supplementary lighting may be provided for individual points in the room (task lighting, accent lighting).
Beam spread is defined by the angles of the beam emitted by a luminaire or reflector lamp. It is determined by the design of the reflector. For uniform illumination (general lighting, task lighting), luminaires with a wide beam spread are required. For accent lighting, a narrower beam of light is needed. Wide-angled lighting is described as "flood" or "wide flood" lighting; narrow-beam lighting – e.g. with a beam spread of 10° - is referred to as "spot" lighting.
Bridge Arm Luminaires
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The CE symbol is not a safety test symbol like the VDE-, ENEC or GS symbols. It is used by manufacturers on their own responsibility - applied to product or packaging - and acts as a signal to the authorities responsible for monitoring certain European Union directives. So a product displaying only the CE symbol has not been tested by a recognised testing agency.
Classes of Protection
Luminaires are divided into three classes of protection according to the protective measures taken against electric shock:
Class I: Luminaires for connection to the line-side PE conductor. The symbol is shown at the point of connection.
Class II: Luminaires with additional or increased insulation. They have no PE conductor terminal.
Class III: Luminaires operated on protective extra-low voltages.
Clean Room Luminaires
Low air particulate loading, high cleanness and hygiene standards – these are prime requirements for both clean rooms and the luminaires used in them. Generally protected to IP 65, clean room luminaires are used in operating theatres, pharmaceutical and food production plants, microelectronic manufacturing facilities and DP systems rooms. Lamps: three-band fluorescent or compact fluorescent lamps.
The colour rendering of a lamp indicates the effect its light has on the appearance of persons or coloured objects. This is rated by reference to the "general colour rendering index" Ra, which indicates how natural colours appear under a lamp's light. The colour rendering index is based on eight frequently found test colours. Ra = 100 is the best rating; the lower the index value the poorer the colour rendering properties. Lamps with an Ra index less than 80 should not be used in interiors where people work or spend lengthy periods of time.
The colour temperature of a light source is defined as the temperature (in degrees Kelvin) at which a black body or Planckian radiator has the same colour appearance as the light source being measured. The values are often only the most similar colour temperatures because a black body cannot assume every colour appearance. The colour temperatures of normal commercial lamps are divided into three groups: below 3,300 °K (warm white), 3,300 – 5,300 °K (neutral white) and over 5,300 °K (daylight white).
Column luminaires are exterior luminaires for mounting on columns or column arms.
Continuous rows are formed by continuous-row luminaires with tubular fluorescent lamps.
Control and regulation
Control and regulation systems heighten lighting comfort and save energy - e.g. by taking account of incident daylight. Where system settings are defined by external factors (e.g. by the push of a button or a light sensor installed separate from the lighting system). the process is known as control; where they are defined by setpoint/actual-value comparison (by a sensor within the lighting system), it is known as regulation.
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DALI (Digital Addressable Lighting Interface) is a standardized digital interface for electronic ballasts operating fluorescent lamps. Unlike the analogue interface (1-10 V) it supersedes, DALI can address and control operating devices individually.
Daylight Systems direct daylight into the depths of the building to assure a uniform special illumination. They protect from direct sunlight and also from excessive warmth especially during summertime. Daylight systems also acvpoid glare in work areas with reduced luminance and consequently allow for a superior illumination of VDU workstations.
Degree of Protection
The degree of protection assigned to a luminaire is a guarantee of safe and reliable operation. The IP code (standing for "Ingress Protection") consists of two numerals. The first (1 to 6) indicates the degree of protection against solid foreign bodies, the second (1 to 8) attests to the degree of waterproofness. Higher degrees of protection include those lower down the scale. Where one of the two numerals is missing, its place is taken by a capital "X", which means "untested".
Dimming enables the brightness of individual lamps or groups of lamps to be controlled. It changes the lighting atmosphere, permitting adjustments to suit different room uses (comfort dimming). Increasingly, dimming is also used to save energy (power dimming), e.g. in daylight-dependent office or factory lighting systems. Incandescent lamps and tungsten halogen lamps (230 Volt) can be dimmed with leading phase angle control dimmers, as can low-voltage tungsten halogen lamps operated by magnetic transformers. Lagging phase angle control dimmers are mainly used for dimming low-voltage tungsten halogen lamps on electronic transformers. They are also suitable for incandescent lamps and tungsten halogen lamps (230 Volt). Compact fluorescent lamps and tubular three-band fluorescent lamps need to be operated by dimmable electronic ballasts (EBs).
DIN 5035 Artificial lighting of interiors
Part 1 Concepts and general requirements (entirely superseded in September 2002 by DIN 12665)
Part 2 Guideline values for indoor and outdoor workplaces (largely superseded in March 2003 by DIN EN 12464-1)
Part 3 Special recommendations for lighting in hospitals (largely superseded in March 2003 by DIN EN 12464-1 and supplementing draft national standard E DIN 5035-3)
Part 4 Special recommendations for lighting in educational establishments (largely superseded in March 2003 by DIN EN 12464-1)
Part 5 Emergency lighting (entirely superseded in July 1999 by DIN EN 1838)
Part 6 Measurement and evaluation Part 7 Lighting for rooms with VDU workstations and workplaces with VDU facilities (partly superseded in March 2003 by DIN EN 12464-1 and supplementing draft national standard E DIN 5035-3)
Part 8 Special requirements for task lighting in offices and office-like rooms.
DIN 5044 Stationary Traffic Lighting - Street Lighting for Automobile Traffic; Part 1: General Quality Criteria and Guide Values; Part 2: Calculation and Measurement.
Lighting of street tunnels and underpasses Part 1:General quality characteristics and guide values Part 2: Calculation and measurement.
DIN 67528 is the German standard regulating "lighting for parking areas and indoor car parks". It was produced in collaboration with the Federal Ministry of Transport, the Federal Institute for Highway Engineering and the Road and Traffic Research Institute with the assistance of the motoring organization ADAC.
DIN EN 12193
DIN EN 12193 "Light and lighting - Sports lighting" applies in all the member states of the European Union. It replaced the national standard DIN 67526 Parts 1, 2 and 4 in November 1999.
DIN EN 12464
DIN EN 12464 Light and lighting – Lighting of work places, Part 1 Indoor work places (cited as DIN EN 12464-1). Many parts of the national standard DIN 5035 were superseded by this European standard in March 2003. DIN EN 12464 on "Outdoor work places" is at present only a draft document and not yet operative.
DIN EN 12665
DIN EN 12665 "Light and lighting – Basic terms and criteria for specifying lighting requirements" defines terms in common use for numerous applications. This standard applies in all the countries of the European Union.
DIN EN 1838
DIN EN 1838 "Emergency lighting" applies throughout the European Union. In Germany, it supersedes national standard DIN 5035 Part 5.
DIN EN 60529
DIN EN 60529 + A1 "Degrees of protection provided by enclosures (IP code)" defines terms used for the degrees of protection provided for electrical equipment by enclosures. Central issues are the designations and requirements of each degree of protection identified by the IP (Ingress Protection) code. This standard applies in all the countries of the European Union; "A1" is an amendment formulated after the standard was published.
DIN EN 60598
DIN EN 60598/A1 "Luminaires", Part 1 "General requirements and tests" describes the mechanical and electrical design of luminaires with an electrical light source up to 1,000 Volt supply voltage as well as the tests required for them. This standard applies in all the countries of the European Union; "A1" is an amendment formulated after the standard was published.
DIN VDE 0100
DIN VDE 0100 "Erection of power installations with rated voltages up to 1,000 V" is a regulation governing the erection and testing of electrical installations. The standard consists of 7 groups (100 – 700): Scope, object and fundamental principles (Group 100), Definitions (Group 200), Assessment of general characteristics (Group 300), Protective measures (Group 400), Selection and erection of electrical equipment (Group 500), Verification (Group 600) and Requirements for special installations or locations (Group 700).
DIN VDE 0108
DIN VDE 0108 "Power installations and safety power supply in communal facilities".
Direct lighting is where luminaires cast their light directly into the room onto surfaces or zones where light is needed. See also indirect lighting.
A combination of direct and indirect lighting in a room is generally found agreeable. This can be provided by using luminaires designed solely for direct lighting in conjunction with models designed exclusively for indirect lighting. However, there are also many luminaires available which combine direct and indirect lighting in a single light fitting: pendant surface-mounted ceiling luminaires and standard luminaires. As a general rule, most of the light cast by these luminaires is indirect (cast onto ceiling or walls); direct lighting is provided by an additional light exit underneath.
The objective of this Directive is to promote the improvement of the energy performance of buildings within the Community, taking into account outdoor climatic and local conditions, as well as indoor climate requirements and cost-effectiveness. Even the lighting of a building is affected by this directive.
Downlight has become an established term for ceiling luminaires of normally round design fitted with reflectors and other optical control elements. Downlights can be fixed or swivel-mounted and are designed for recessed mounting in ceilings (recessed downlights) or for surface-mounting on ceilings (surface downlights). Downlights are also suitable for illuminating the interior of cabinets or showcases. Downlight are commonly designed for use with low-voltage tungsten halogen lamps, compact fluorescent lamps or metal halide lamps.
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EB stands for electronic ballast. EBs and dimmable EBs are increasingly being used instead of conventional or low-loss ballasts. They reduce power consumption and make for a high degree of visual comfort. Other advantages: higher luminous efficacy of lamps, flicker-free instant starting, longer lamp life, automatic disconnection of defective lamps.
ELDACON®, the light control technology developed by Siteco, guarantees a high level of illuminance at the workstation without the possibility of light sources appearing glaring. The light of T16 (T5) fluorescent lamps is precisely guided from the optical system via a microprismatic structure onto the working plane. Reflected light and direct glare are hereby reduced to a minimum. The surfaces have a uniform illuminatiuon and impart a crystal-clear, bright and brilliantly aesthetic ambience.
ENEC is the European safety test symbol for luminaires and other electrical products. It is awarded by independent test and certification institutes in Europe. In Germany this is VDE, which awards products tested in Germany the testing agency number "10". The acronym ENEC stands for European Norm Electrical Certification.
Escape Sign Luminaires
Safety signs for escape routes are available as back-lit signs - i.e. escape sign luminaires - or illuminated safety signs. Both need to conform to certain quality criteria set out in DIN EN 1838, notably in terms of colour, luminance of the safety colour green, luminance contrast and sign dimensions.
For medical examinations, at least 1,000 lux is required at the point of examination. This is delivered by swivellable, extendable examination luminaires. Featuring an articulated arm, they are positioned and repositioned by means of a handle integrated in the luminaire head. These luminaires are available in designs for ceiling and wall mounting or as portable models on stands. The lamps in most widespread use are line- and low-voltage tungsten halogen lamps.
Explosion Protected Luminaires
Explosion-protected luminaires meet fire protection standards and more. For zone 20 applications, for example, they conform to degree of protection IP 5 upwards and feature an impact-resistant luminaire enclosure. DIN VDE 0165 defines zones according to the risk of explosion present. Luminaires used in them need to be designed for the appropriate zone. Zones 0 (constant long-term risk), 1 (occasional risk) and 2 (short-term risk) are for combustible gases, vapours and mists; zones 20 (long-term or frequent risk) and 21, 22 (short-term risk due to occasional swirling) are for combustible dust.
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Fibre-Optic Lighting Systems
In fibre-optic lighting systems, a bundle of fibre-optic cables distributes the light of a single, centrally operated high-pressure discharge lamp. The fine, flexible cables can also be laid underground or in water in places which are difficult to access. At the exit point of each cable, lenses or colour filters determine the direction and impact of the light.
Fire Protection Symbols
The letters "F" or "M" in inverted triangles are fire protection symbols. They indicate the degree of limitation of the heat a luminaire generates and the kind of flammable materials on which the luminaire may be mounted (see table). For all luminaires bearing these symbols, it is imperative that manufacturers' mounting instructions should be observed. The fire protection symbol "D" in an inverted triangle (formerly two "F" triangles) indicates that the heat the luminaire generates is adequately limited for use in industrial and workshop interiors where dust constitutes a fire hazard.
Floodlights are designed for lamps with high power (Watt) ratings. Lamps with lower power ratings are used in spots or mini-floods. In exterior lighting, floodlights lend themselves to applications such as illuminating buildings; indoors, their principal application is theatrical stage lighting.
Full-spectrum lamps are linear three-band fluorescent lamps with a 26 mm or 16 mm diameter. The spectral composition of the light they produce corresponds to that of daylight (hence the term "daylight spectrum lamp", which is also used to denote these light sources). Their light thus also has a higher ultraviolet (UV) content than the light of ordinary fluorescent lamps. To guard against the harmful effects of excessive exposure to UV radiation, UV content is reduced in lamps for general lighting. Because of the higher UV content of the light they generate, full-spectrum lamps are also used for medical/therapeutic purposes. They permit controlled use of UV radiation, which is known to be harmful in excessive doses (e.g. causing "sunburn").
Light colour and colour rendering properties correspond to those of other daylight-white (965) de-luxe fluorescent lamps.
General lighting - also referred to as basic lighting - is the uniform room lighting which takes no special account of visual tasks performed at different points in the room. General lighting makes sure that architecture, objects and people in the room are visible. It provides an overview and permits orientation. Supplementary lighting may be provided for individual points in the room (task lighting, accent lighting).
Glare can be caused directly by luminaires or other surfaces with excessively high luminance, e.g. windows (direct glare). Direct glare is assessed by the UGR method. It can also be caused in directly by light reflecting from shiny surfaces (reflected glare). Glare impairs visual performance (physiological glare) and visual comfort (psychological glare).
The GS symbol shows that a product meets the requirements of the German Equipment Safety Act. It may only be used in conjunction with the symbol of an authorized testing agency, e.g. VDE or TÜV.
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Illuminance (symbol: E) is measured in lux (lx) and indicates the amount of luminous flux from a light source falling on a given surface. Illuminance is 1 lux when an area of 1 square metre is uniformly illuminated by 1 lumen luminous flux. Illuminance is measured on horizontal and vertical surfaces, using an illumination photometer. Where a white room and a dark room are provided with the same lighting, the white room appears brighter.
Incandescent lamps are typical thermal radiators. They consist of an evacuated glass bulb containing a tungsten filament, which glows when heated by an electrical current to around 2,600 – 3,000 degrees Kelvin. Most of the radiation emitted is in the infrared range.
Indirect lighting is where light from luminaires is directed only onto ceilings or walls and is reflected by them into the room. Lamps are screened from view and light emission above eye level prevents glare. Indirect lighting is generally used in combination with direct lighting since on its own it can create a monotonous atmosphere with shadows too pale for good modelling. Where indirect lighting is used, the reflectance of ceiling, walls and floor should not be too low; in many cases, this would make it an impractical lighting option for reasons of energy efficiency.
Intensity distribution describes the way luminous intensity is distributed in the room. Shape and symmetry of intensity distribution indicate whether a luminaire (or reflector lamp) casts a narrow or wide-angled beam and/or provides symmetrical or asymmetrical lighting. Intensity distribution is indicated by IDCs, intensity distribution curves on a graph. These are formed by joining the points on a polar diagram showing the luminous intensity generated at different angles by a luminaire (or reflector lamp).
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No lamp, no light. The term "lamp" refers to an engineered artificial light source, e.g. incandescent lamp, energy-saving lamp, compact fluorescent lamp. Lamps are used in luminaires, which distribute and direct the lamps' light and prevent it causing glare.
LED stands for "light emitting diode". This is an electronic semiconductor component which, when energised, generates red, green, yellow or blue light. Furnished with an internal luminescent coating, a blue LED yields white light. LEDs are used for orientation or pilot lighting and increasingly for general lighting purposes. The primary advantages of LED technology: long service life, no maintenance, IR/UV-free lighting, low energy consumption and chromatic stability.
Light is the visible radiation that can be perceived by the human eye. It accounts for only a narrow band of the full spectrum of electromagnetic radiation, which also encompasses gamma, X-, infrared and UV (radio wave) radiation. The spectral range of light embraces wavelengths from 380 to 780 nm and is divided into the various colour sections ranging from violet through blue, green and yellow to red. Outside this band, the human eye cannot "see" radiation.
A few other parts of the electromagenetic spectrum may not be visible to the eye but they are still perceived: IR radiation warms, UV-A radiation tans.
Light colour describes the colour appearance of a lamp's light. Light colours are based on colour temperature expressed in degrees Kelvin (K):
warm white (ww) < 3,300 K
neutral white (nw) 3,300 K to 5,000 K
daylight white (dw) > 5,000 K.
Lamps with the same light colour can have different colour rendering properties. Light colour helps create the atmosphere of a room: warm white light is found cozy and comfortable; neutral white light creates a more businesslike atmosphere. Daylight white light is only suitable for interiors where illuminance exceeds 1,000 lux; where illuminance is lower, daylight white light makes the surroundings look pale and monotonous.
Shadow, brilliance and colour-rendering are importabnt qualitative criteria for artificial light. They are decisive for the special properties of architecture and for the recognition of rhythm and material qualities.
Light for Vitality
The Siteco claim ‘Light for vitality’ is supported by perceptions about the well-being of people under conditions of daylight, and its effect as an internal clock for the body’s biological rhythm. When planned correctly, light can be implemented more strongly than before as a factor influencing productivity. Intelligent systems such as lighting management software, daylight systems, luminaire modules with a high illuminance level, clever light directing technologies such as Eldacon and Siteco Mirrortec make sure that the biological rhythm of people harmonises with their everyday work in industry or in the office.
Lighting systems are light-emitting installations capable of causing "light pollution" if luminaires are wrongly positioned or incorrectly angled. In the case of a streetlighting system, for example, this could cause disturbing light to be cast into residents' homes. Measurement and assessment methods are published by Deutsche Lichttechnische Gesellschaft (LiTG).
Light sensors monitor the illuminance of daylight or artificial lighting (brightness sensor). They are a component of photoelectric lighting controllers and other lighting control and regulation systems.
In street lighting especially, luminaires are frequently referred to as light sources.
Controlled use of light – light therapy – can alleviate the downside impact of lifestyle, environment or personal development. It helps shift workers and people suffering from jetlag, for example, to overcome the sleep disorders that can be caused by disturbance of our "inner clock" (circadian rhythm). It can also help boost motivation, especially for those suffering from SAD (seasonal affective disorders), a syndrome which can bring down spirits in the dark months of the year as a result of lack of natural daylight.
Light therapy products are often fitted with full spectrum lamps.
Lighting level is the mean illuminance in a room or at individual points in a room. The term is also used where the key lighting quantity is luminance, not illuminance, e.g. in street lighting.
These are luminaires with a louver enclosure, mostly designed for use with tubular fluorescent lamps or compact fluorescent lamps. Louvers are optical controllers: they define the intensity distribution of the luminaire and at the same time prevent glare.
Lowered Night-Time Lighting
The level of street lighting at night is lowered during the hours when traffic is light in order to save energy. For single-lamp luminaires, this involves reducing the lamp power of each individual light source, e.g. from 80 W to 50 W (power reduction). Switching off single-lamp luminaires would affect the uniformity of the lighting and compromise road safety. Switching off luminaires for lowered night-time lighting is possible only where two or more luminaires are mounted on the same column (one luminaire always stays on) or where luminaires are twin-lamped (one lamp always stays on).
The term "luminaire" refers to the entire electric light fitting, including lamp. Luminaires protect lamps, distribute their light and prevent it causing glare. Luminaires are differentiated on the basis of type lamp (incandescent, fluorescent, discharge lamps), number of lamps (single-lamp, twin-lamp, etc.) intended location (interior luminaires, exterior luminaires), degree of protection (luminaires for dry, damp and dusty interiors), type of construction (open luminaires, enclosed luminaires, reflector luminaires, specular reflector luminaires, louvered luminaires, diffuser luminaires, floodlights) and application (technical luminaries, decorative luminaires).
Luminaire spacing is the distance between light sources (= luminaires) in a street lighting system.
Luminance (symbol: L) is the brightness of a luminous or illuminated surface as perceived by the human eye. It is measured in candelas per unit area (cd/m²). For lamps, the more convenient unit of measurement cd/cm² is normally used.
Luminous efficacy is the measure of a lamp' efficiency. It indicates how many lumens (lm) per watt a lamp generates. The higher the ratio of lumens to watts, the more light a lamp produces from the electricity it consumes. Examples: incandescent lamp 12 lm/W, tungsten halogen lamp 20 lm/W, energy-saving lamp 60 lm/W, tubular three-band fluorescent lamp 90 lm/w.
Luminous flux (Φ) is the rate at which light is emitted by a lamp. It describes the visible light radiating from a light source in all directions and is measured in lumen (lm).
Luminous intensity (symbol: l) is the amount of luminous flux radiating in a particular direction. The way luminous intensity is distributed in the room (intensity distribution) defines the shape of the beam of a luminaire or reflector lamp. Luminous intensity is measured in candelas (cd).
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The lighting quantity recommendations set out in European lighting standards such as DIN EN 12464-1, e.g. for levels of illuminance, refer to values that need to be maintained. This means that the lighting quantities in question must never fall below them. However, because lamps, luminaires and room surfaces are subject to ageing and soiling, the values that are registered when lighting is new decline as operating time increases. So, to enable a lighting system to be operated longer without additional maintenance work, values on installation need to be correspondingly higher. How much higher is determined by maintenance factors.
Maintenance factors depend on operating conditions as well as on the type of lamps, electrical gear and luminaires used. They need to be defined and recorded by designers (and operators) and form the basis of maintenance schedules. Values required on installation are calculated as follows: value on installation = maintained value / maintenance factor.
Medical Supply Units
Installed at the head of a patient's bed, a medical supply unit incorporates all the supply lines, connections and controls needed to supply the patient with lighting, power, communication facilities and medical gases. Depending on the design of the unit, it features a number of luminaires: for general lighting, reading lighting, examination lighting, night watch lighting. As well as conventional horizontal systems, there are now vertical supply units available which give a more homely touch to the room.
A projector emits a light beam that is dispersed with a deflection reflector and reflected without glare back into the spacial area.This technology was implemented for the first time by Siteco under the name of "Mirrortec", and was further developped for numerous other applications.
Motion or presence detectors react to bodies moving within a pre-defined monitoring zone. They are available in a variety of technical designs (passive infrared (PIR), radar or ultrasound sensors). When movement is detected, they activate a light for a pre-specified time set by a timer. Depending on application (e.g. office or corridor), detectors need to be tuned for different degrees of sensitivity to movement. To prevent lights being switched on and off in daylight, motion detectors should be governed by a light sensor.
In the context of exterior lighting, the term mounting height means the height from which light falls on an illuminated surface.
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Operating Theatre Lights
Special operating theatre lights (DIN EN 60601-2-41 compliant) are used for illuminating the operating field. Today, these lights are normally incorporated in operating theatre lighting and supply systems.
Orientation lights are special luminaires designed to provide (a relatively low level of) lighting for guidance, not illumination.
Outlet pillars with power cable and multiple power points permit central control of mobile luminaires for park and garden lighting.
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Pedestal luminaires can be mounted on walls or pillars for outdoor lighting.
Ceiling luminaires can be mounted in or on the ceiling but they can also be suspended from the ceiling. "Pendant luminaire" is a term mostly used to denote a luminaire for the home (e.g. for table lighting). Luminaires used in offices or industrial interiors are generally referred to as "suspended luminaires". They are suspended (also in continuous rows or as power track) on steel wires or threaded rods.
Photoelectric Lighting Controllers
Photoelectric lighting controllers automatically switch lights on and off when a pre-defined level of brightness is reached. The brightness is monitored by an integrated light sensor. Its sensitivity should be infinitely adjustable, e.g. from two to 2,000 lux for outdoor lighting.
Power consumption is the electrical energy in Watts (W) consumed by a lamp (also referred to as lamp power or wattage) or a ballast. In the case of low-pressure and high-pressure discharge lamps, lamp power plus ballast power consumption is referred to as system power (consumption).
Power track makes for flexibility. Luminaires and spots can be positioned anywhere along the track by means of adapters, which also establish the electrical connection. The current conductor is exposed on the inside of the track. Power track systems are available for low-voltage, single-phase and three-phase operation, all of them suitable for surface-mounting on ceilings, recessed ceiling mounting, suspended mounting on ceilings or wall mounting. Cross, angle and variable connectors enable power track sections to be linked to form straight or rectangular structures and curved power track sections permit the formation of arcs.
Projector-Reflector Lighting Systems
Projector-reflector lighting systems are luminaires in which light generated in a projector is diffused and directed onto the illuminated surface by a facetted reflector. The angled surfaces of the reflector break up the directional light beam, thus preventing the glare that would be caused if the light was re-directed without optical control.
In streetlight designs, the reflector normally forms the luminaire canopy. For interior lighting, the preferred solution is generally one where projector and reflector are separate units and not part of a single luminaire in the conventional sense.
Protective Extra-Low Voltage
Electrical circuit with low rated voltage, which is supplied but securely separated from higher-voltage circuits. Luminaires suitable for operation on protective extra-low voltages need to be identified as such. They are assigned Protection Class III.
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Recessed Ceiling Luminaires
Luminaires for mounting in cavities or ceiling voids. Most of the luminaire is recessed in the ceiling and thus not visible. In many cases, the luminaire face is flush with the ceiling.
Reflectance indicates the percentage of luminous flux reflected by a surface. The reflectance of light surfaces is high; that of dark surfaces is low. White walls reflect up to 85 percent of the light that strikes them, while light-coloured wood panelling reflects as much as 35 percent. The reflectance of red brick, however, is only 15 percent. So the darker the decor and furnishings, the more light is needed to produce the same illuminance at the working plane.
Polished and highly polished reflectors in luminaires and reflector lamps are used as light controllers. Depending on their design, they produce different intensity distribution curves and beam spreads.
Reflector lamps have an integrated reflector (glass bulb with internal reflecting coating) which directs their light and determines beam spread. Reflectors are incorporated into normal incandescent lamps, PAR incandescent lamps and low-voltage tungsten halogen lamps.
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Semi-cylindrical illuminance is the amount of vertical illuminance that falls on a semi-cylindrical surface. It is essential for identifying approaching figures outdoors or in indoor car parks and needs to be at least 1 lux at a height of 1.5 metres above the ground.
According to DIN EN 12665 (borrowing from the International Lighting Vocabulary) the shielding angle of a luminaire is the angle between the downward vertical and the first line of sight at which lamps and luminous areas are directly visible. DIN EN 12464-1 "Lighting of indoor workplaces" defines shielding angle by reference to the horizontal plane. Where the correct shielding angle is not observed, there is a risk of direct luminaires causing direct glare due to excessively high luminance.
The wavelengths of the electromagnetic rays in the visible spectrum - i.e. light - range from 380 to 780 nanometres (nm; 1 nm = 109 m), each wavelength having a distinct spectral colour. These colours can be made visible by a prism, as in the case of a rainbow, which is created by raindrops acting as prisms.
Spots are luminaires used mainly for directional lighting. They are available for use with reflector lamps or in designs with reflectors incorporated into the luminaire and can be mounted on ceilings, walls, power track, wires or rods. Spots for exterior lighting - including those in earth-spike designs - need a higher degree of protection. Spots are often rotatable and swivel-mounted.
Standard luminaires (also referred to as stand-alone luminaires) are non-static luminaires with shades, optical control materials or reflectors which direct the light in different directions according to their design.
Street lighting makes for greater safety. This is because we rely on our eyes for more than 80 percent of the sensory impressions we register. So poor visual conditions heighten risks for all road users. The duty to ensure road safety (enshrined in Germany in Section 823 - Compensation - of the Civil Code) includes a duty to provide street lighting in built-up areas and on stretches of road where special hazards are present, such as crossroads, bottlenecks, etc., or where the road surface is damaged. As such hazards present a heightened risk of accident, street lighting is a legal requirement at these points both in and outside built-up areas.
The majority of luminaires for lighting thoroughfares and collector, local service and residential streets are designed for mounting on columns. There are also streetlighting luminaires for suspending on catenary wires or for mounting as wall luminaires. Decorative exterior luminaires for pedestrian precincts, squares, parks and gardens are also generally classed as streetlighting luminaires.
Surface-Mounted Ceiling Luminaires
Luminaires for mounting directly on the ceiling. The luminaire housing is visible.
This is lighting designed to supplement general lighting and cater to the special visual requirements of tasks performed at different points in the room. One example is bathroom mirror lighting, another is a reading lamp beside an armchair.
The transformers that are normally used in lighting reduce 230V line voltage (primary side) to 6, 12 or 24 volts (secondary side). Low-voltage spots and other low-voltage luminaires without built-in transformers need to be operated with individual or collective upstream transformers. Aside from conventional transformers, which work by transferring energy from a primary to secondary windings, toroidal transformers are a popular choice. Electronic transformers are another option. They are smaller, more compact, lighter, quieter and they consume less electricity.
Tungsten Halogen Lamps
In terms of technical design and in the way they work, tungsten halogen lamps are similar to incandescent lamps. The gas with which they are filled, however, contains halogens or halogen compounds. Within a certain temperature range, these additives enable volatizing tungsten atoms to be redeposited on the filament and and thus prevent blackening of the bulb and the consequent decrease in luminous flux. This makes for higher luminous efficacy and a longer life compared with incandescent lamps. Also, owing to the much smaller dimension of the burner and filament, precise optical control is possible.
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The "Unified Glare Rating" method (UGR) is a method developed by the International Lighting Commission CIE (Commission International de l'Eclairage) to standardized glare assessment worldwide.
For the performance of a visual task, it is important to ensure not only the right lighting level but also the right degree of uniformity in the way the brightness is distributed. The yardsticks for this are uniformity of luminance and uniformity of illuminance, each expressed as a ratio between lowest and mean or lowest and highest values.
Generally found as standard or wall luminaires, uplights direct most of their light upwards onto the ceiling to be reflected back into the room as indirect lighting. In uplights with a direct lighting component, the bottom of the reflector is translucent.
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The VDE symbol of the German test and certification institute VDE Technisch Wissenschaftlichen Verbandes der Elektrotechnik Elektronik Informationstechnik e.V. shows that an electrical product meets the standard safety requirements for protection against electrical, mechanical, thermic and other hazards. The VDE also awards the European safety test symbol ENEC.
For visual comfort, a lighting system needs to meet at least all standard lighting quality requirements and must contribute to the interior design of the room. Visual comfort is enhanced by higher quality lighting, e.g. the quality of lighting attained by the use of electronic ballasts (EBs) for fluorescent lamps.
Visual performance is determined by the visual acuity of the eye and its sensitivity to differences in brightness and darkness. Time is another factor: the time it takes a motorist, for example, to make out differences in brightness, shapes, colours and details (speed of perception).
Visual tasks are defined by light/dark and colour contrasts, by the size of details and by the speed at which contrasts need to be perceived. The harder the visual task, the higher the lighting level needs to be.
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Wall luminaires are used for task lighting, as part of the general lighting in a room and as a source of supplementary, accentuating light. They generally belong to a luminaire "family" of uniform design.
Wire and Rod Systems
Low-voltage wire and rod systems are similar to classical power track in that they make for flexible lighting. Low-voltage spots and luminaires can be mounted at any point and relocated at any time. They are screwed or clipped in place or attached by plug-in adapters. Current is carried to the luminaires by the wires or rods (or metal strips), which double as power lines. They are attached to walls, mounted directly on the ceiling or suspended from the ceiling. Connection elements permit geometrical structures. Important note: the transformer must always be operated at rating. Wire and rod systems are now also available for 230 Volt operation.
Working plane is the term used to denote the horizontal or vertical plane which artificial lighting is required to illuminate. Depending on the purpose of the lighting, industrial standards stipulate a mathematical reference point - e.g. 0.75 m above floor-level - where illuminance should be