Selection of Lamps

Table of Contents

Selection of lamps

The first step in the selection of lamp is to select the range of lamps satisfying the quality requirements such as colour properties, glare etc. and then select the lamp which has the highest efficacy within the group. Selection criterion are:

  • Luminous efficacy.
  • Luminous flux and lumen depreciation over time.
  • Damage factor.
  • Colour parameters. (Colour rendering, colour temperature and colour shifting).
  • Average lamp life.

Incandescent Lamps

Incandescent Lamp emits spectrum of white light

Fluorescent Lamps


Two parts- gas filled tube & ballast

Energy flow through gas → emit UV light → Excite phosphor coating → coating emits white light.

Phosphor emits light in a very narrow frequency range (CRI is 80 % (max).

Mixing of different phosphor to emit red, green & blue spectra (But as we mix more number of phosphor, the process become inefficient)

CFL give less light later in their life span.

May fail to operate at low temperature as light output drops at low temperature.

Dimming is possible.

LED Lamps


A LED is a semiconductor device which converts electricity into light. Earlier white light from LEDs was only possible by combining of three LEDs, red, green, and blue, and controlling the current to each. This changed in 1993 when Nichia created a blue indium gallium chip with a phosphor coating that is used to create the wave shift necessary to emit white light from a single diode. This process is much less expensive for the amount of light generated.

Each diode is about 6mm in diameter and uses about 10 mA to operate at about a tenth of a watt. LEDs are small in size, but can be grouped together for higher intensity applications.

LED fixtures require a driver which is analogous to the ballast in fluorescent fixtures. The drivers are typically built into the fixture (like fluorescent ballasts) or they are a plug transformer for portable (plug-in) fixtures. The plug-in transformers allow the fixture to run on standard alternating current (AC), with a modest (about 15 to 20 percent) power loss.

The efficacy of a typical residential application LED is approximately 20 lm/W (?? source ??), though efficacies of up to 100 lm/W have been created in laboratory settings.


  • Low energy consumption – retrofit bulbs range from 0.83 to 7.3 Watts.
  • Long service life – LED bulbs can last up to 50 000 hours.
  • Durable – LED bulbs are resistant to thermal and vibrational shocks and turn on instantly from -40 °C to 185C°, making them ideal for applications subject to frequent on-off cycling, such as garages and basements.
  • Good for accent lighting on account of directional distribution of light.
  • No infrared or ultraviolet radiation – excellent for outdoor use because UV light attracts bugs.
  • Safety and environmentally conscious – LEDs contain no mercury or lead and remain cool to the touch.
  • Fully dimmable – LEDs do not change their color tint when dimmed unlike incandescent lamps that turn yellow.
  • No radio interference – no ballast.
  • Range of color – LEDs can be manufactured to produce all colors of the spectrum without filters, they can also produce white light in a variety of color temperatures


  • LEDs are currently more expensive than more conventional lighting technologies.
  • LED are very heat sensitive-  Excessive heat or inappropriate applications dramatically reduces both light output and lifespan.
  • LEDs typically cast light in one direction at a narrow angle compared to incandescent or fluorescent lamps so lenses or reflectors are needed in fixtures to broaden the beam (if desired).


LEDs are better at placing light in a single direction than incandescent or fluorescent bulbs. Because of their directional output, they have unique design features that can be exploited by clever designs. LED strip lights can be installed under counters, in hallways, and in staircases; concentrated arrays can be used for room lighting. Waterproof, outdoor fixtures are also available. Some manufacturers consider applications such as gardens, walkways, and decorative fixtures outside garage doors to be the most cost-efficient. Uses include:

  • Task and reading lamps
  • Linear strip lighting
  • Recessed lighting
  • Porch/outdoor/landscaping lighting
  • Art lighting
  • Night lights
  • Pendants and overhead
  • Aviation lights at telecom towers

LED String

LED String is a sophisticated lighting system (string and driver) that can be directly mounted to a sign back plate or other substrate. The string is flexible, water resistant and robust which allows new designs for signage and architectural applications. The system is specifically suitable for large projects where economical solutions are looked for. With LED String, the running costs can be reduced compared when using neon or fluorescent solutions.Both white and colored versions are available. Each LED device in the string comprises a sealed LED and heat sink – all with specially optimized optical and thermal characteristics.

Features and benefits: 

LED String’s energy consumption is around 4 W/m (e.g. for red) compared to 20 W/m of e.g. a neon lamp. Maintenance costs are lower; the lifetime of the LED String system is around 50 000 h whilst neon or fluorescent lamps only lasts 20 000 h.


The LED String System operates at only 33 V. This means that there is no fire risk as with systems operating at about 1000 Volt.


LED String is very robust and will not easily break as a neon or fluorescent lamp.


Because of its low dimensions, we can create slimmer signs or architectural designs. It is easy to optimize the brightness of the design.

Applications: They can be used both indoor and outdoor for sign lighting, band lighting (in e.g. petrol stations) and architectural designs.

LED Power Driver 

LED Power drivers have a universal mains input (100 -240 V) and generate DC at 24 V DC voltage. The LED Power Drivers have an operating life matching that of LEDs (50 000 h). The range consist of a slim 20 W version with a plastic housing and 60 and 100 W versions with a metal housing. Low temperature performance (-30 °C) for outdoor application. These are hazard free as all the major safety requirements are met. LED Power Drivers generate a limited output voltage.

Selection of control gear

Selection criterion are:

  • Ballast loss.
  • Harmonic considerations.
  • Effects of the control gear on the lamp.

Selection of Luminaire

For energy efficient design, space height ratio is to be considered. With a better luminaire space height ratio of 2.3 : 1 can be achieved compared to 1.5 : 1, thus reducing the number of fittings as well. Criteria to be considered:

  • Light output ratio.
  • Optical systems (reflectors, louvers, etc.) and their distribution.

The other factor to be considered is the prevention of pollution, as thermal load generated by fittings provides chance for environmental pollution. Following should be considered to improve the environmental performance of products:

  • Energy Consumption
  • Service life
  • Hazardous substances content
  • Amount of packaging materials used
  • Product weight
  • Recycling potential

The lifetime of a lighting system is one of the most important buying criteria since it determines the running cost of the system for years to come. Running costs of a lighting system are the sum of the energy costs, lamp replacement cost (new lamp purchases and the cost for replacing the old lamps) and lamp disposal fees (if applicable). The cost of lamp replacements can be high when the lamps are not easily accessible and/or in situations were the re-lamping exercise creates nuisance (roads, tunnels, working environment, industrial production processes, shops, etc.).

The life of a lighting system depends mainly on the lamp life and the life of components like starters, transformers and ballasts. There are two important lifetime definitions:

  • Average life time: the time at which 50% of a certain batch of lamps will have failed

  • Service lifetime: 

    the time that a user defines as optimal to replace (all) the lamps taking into account the risk that lamps will fail combined with the lumen depreciation of most lamps over time (sometimes a lamp still operates but the original brightness has come down to an extend that the users do not find comfortable anymore).

Next to lifetime of a lamp in general, the reliability of the projected lifetime is key. Now that more and more professional end-users choose to do the re-lamping exercise group-wise (all lamps at the same time instead of every time an individual lamp fails), it is very important to be able to predict the optimal time for replacing the lamps. Philips Lighting has invested a lot to not only extend the lifetime of its lamps but guarantee the reliability of the expected life times as well.

New lamps developed are having more life like following Philips lamps: MASTERline ES halogen lamps (5 000 hours), CFL (10 000 hours), Mastercolour lamps (12 000 hours), 'TL'5 lamps (20 000 hours), QL induction lamps (60 000 hours) and LEDs with a remarkable life time of 100 000 hours. Many electronic gear inventions have also helped in increasing the lamp life.

High efficiency OLC optics for indoor offices POT optics for road lighting may be used.

Lamp Application Guide

Lamp Application Guide
CategoryDescriptionLuminous Efficacy (lm/W)Colour Rendering IndexTime for full brightnessAverage Burning Life (h)Relative AdvantageMajor Applications
IncandescentGLS Lamps (Gas filled or vacuum) 25-1000 W91000.1 secStd: 1000; Long Life: 2000; Extra Long Life: 4000Excellent colour rendition, instant operation, no accessory required.Domestic lighting, where colour rendition is required. (Being phased out. as per EU guidelines, frosted, pearl and opal are already banned and clear lamps to be phased out.)
Diffuser / Coated Lamps9   Glare free lightStudy rooms
Internal Mirror Reflector Lamps9-16   High intensity beam without external reflector, Glare free light.Display lighting, spot lighting, stage lighting.
Tungsten Halogen Lamps 500-2000 W221002000 Excellent colour rendition, near constant light output with negligible decrements with age.Storage yards, monumental lighting, construction area, security lighting, auditoriums.
Quartz Halogen Lamps25   Excellent colour renditionAuditorium, colour TV filming.
FluorescentTubular w/o internal reflector 20-80 W (Ballast 13-18 W)63-6966-77 7500High efficacy, good colour rendition, long service life.Domestic, office and commercial lighting.
Tubular With Internal Reflector (Ballast 13-18 W)63-7066-77 5000Higher efficacy, external metallic reflector can be eliminated.Domestic, office and commercial lighting.
CFL40-50Fair3 min (80% at starting)8 000-10 000 Domestic, office and commercial lighting, it is very ubiquitous. However, tempered by the use of mercury in its manufacture, its disposal is a problem.
High Intensity DischargeBlended light lamps MLL 100-500 W18-2045 5 000Good colour rendition, no control gear required, high efficacy, no run up timeGarages, shops, low bay workshops, parking areas.
Quartz Discharge Tube Lamps42-57   High efficacy, short run up time, long life.Factories, highways, parking areas, monumental flood lighting, yard lighting.
HPMV Lamps 80-400 W (Ballast 10-30 W)37-5240-45 7500 Industrial and public
HPSV Lamps SON 70-1000 W (Ballast 30-40 W)83-11925 70 W: 10 000; 150 W: 15 000; Choke: 20 000 Golden white light gives a warm appearance and better visual activity, excellent lumen maintenance and very long life, very high energy efficacyHighway lighting, industries,  exhibition sites, flood lighting of monuments, where colour rendition is not important, in foggy atmosphere.
LPSV Lamp 35-180W (Ballast 30-35 W)70-183Poor   Public
HP Metal Hallide Lamps 375-2000 W (Ballast 30-50 W)67-9565   Sports, Stadium, Public
InductionQL lamps67-70Excellent 6 000 Commercial
LED 50-100  45 000 - 100 000High efficacy. Free from hazarduous substances like lead, cadmium and mercury. Also no emission of harmful gases like UV, infrared or of greenhouse gases. Saves in AC as they are cooler.Display lighting, Aviation Obstruction Lights, Panels, Pen lights, Electronics, Places where frequent change is costly or which are inaccessible.


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