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Glossary of Lighting Terms

When it comes to the world of lighting its very easy to get confused by all the 100's of terms. This page clearly details each and every one of them!

2G11 is a type of light bulb base. This base has 4 pins in a straight line and can be found on 18w, 24w, 34w, 36w, 40w, 55w and 80 watt PLL light bulbs. This type of light bulb is also known as Biax L, Lynx L and Dulux L.

2G7 is a type of light bulb base. This base has 4 pins in a straight line and can be found on 5w, 7w, 9w and 11 watt PLSE light bulbs. This type of light bulb is also known as Biax S/E, Lynx S/E and Dulux S/E.

2GX13 is the technical term used to describe the connection pins on a T5 circular fluorescent light bulb. These light bulbs are available in 22w (225mm), 40w (300mm), 55w (300mm) and 60 watt (380mm) versions.

3-Pin BC or BC3 is a type of light bulb base found in new build and rental properties. Light bulbs with this base are fully compliant with Part L of Building Regulations. Standard bayonet light bulbs cannot be used in BC3 lamp holders.

827 can be used to describe the colour of light produced by a light bulb or fluorescent tube. 827 is more commonly known as "warm white" and is similar to the light produced by a normal incandescent bulb.

830 can be used to describe the colour of light produced by a light bulb or fluorescent tube. Colour 830 is primarily found in halogen light bulbs and appears slightly whiter than incandescent light bulbs.

Colour 835 is the standard colour of fluorescent tubes and compact fluorescent light bulbs. Lamps with this colour code are also referred to as having a "White" colour temperature of 3500k.

Colour 840 is also referred to as "cool white", emitting a 4000k colour temperature. Lamps & tubes that produce this colour enhance blues, flatten reds and give a bluish tint to whites & greens.

Colour 845 is also referred to as "cool white". Lamps & tubes that produce this colour enhance blues, flatten reds and give a bluish tint to whites & greens.

860 is more commonly known by the term "daylight". Daylight light bulbs reproduce the colour of the sun on a sunny day. These light bulbs have a colour temperature of 6000 Kelvin.

865 is more commonly known by the term "daylight". Daylight light bulbs reproduce the colour of the sun on a sunny day. These light bulbs have a colour temperature of 6500 Kelvin.

A60 is the technical term used to describe a standard light bulb shape. This shape of light bulb is also known as a GLS (General Lamp Shape).

A60 light bulbs come in Incandescent, Eco Halogen, Energy Saving CFL and LED variations.

Electric current is measured in Amps, short for Ampere. By taking amps and multiplying it by voltage you can then workout the wattage of a product. A standard UK light switch/socket is rated at 13 amps.

ANSI is an acronym for American National Standards Institute. These light bulbs are designated by a 3 letter code such as DAF, DED, DDS and DTY. The unique codes are used to match existing lamps to the exact same wattage, shape and beam angle.

ANSI bulbs are for specialist use and have been designed to meet a strict specification.

AR111 light bulbs are a 111mm diameter spotlight light bulb. This type of bulb is generally used for accent lighting so can be purchased in spot, flood and wide flood versions depending on application.

These light bulbs are also available in dimmable and non-dimmable LED versions.

Arc lamps were the first widely used light bulbs and the only type of light available from 1800-1901. The benefits of carbon arc lamps were the super bright output and the fact they were cheaper to light streets than gas or oil.

Today arc lamps can on be found in xenon short-arc forms.

Architectural light bulbs are unusual incandescent linear lamps that aren't to be confused with fluorescent tubes. These light bulbs are also known as Osram Linestra, Radium Ralina, Philips Philinea and Sylvania Linolite.

Please Note: Traditional architectural light bulbs are slowly being phased out in favour of LED Architecturals

Aurora Lighting are a global manufacturer of energy saving and LED lighting solutions. Founded in 1999 their range of high quality branded products includes Downlights, LED Light Bulbs, LED Tubes, LED Panels and LED Light Fittings.

Ba15d is the technical term for Small Bayonet or SBC capped light bulbs. This base is 15mm in diameter and has two pins which twist and lock into the lamp holder. The "d" at the end of the code refers to the double contact on the bottom of the lamp.

Ba22d is the technical term for Bayonet or BC capped light bulbs. This base is 22mm in diameter and has two pins which twist and lock into the lamp holder. The "d" at the end of the code refers to the double contact on the bottom of the lamp.

An Electrical Ballast is a device that is used to maintain the current in a circuit. Inductive ballasts are used with Fluorescent Tubes, Compact Fluorescents, Metal Halide, Sodium and Mercury light bulbs.

In simple terms Ballast Factor is the percentage of the lamps lumens that the ballast is expected to emit. For example if a ballast had a ballast factor of 0.98 it would be emitting 98% of the lamps rated lumens.

A socket is a hollow object that is used to contain the light bulb base. Sockets are connected to the electrical supply to transfer the power to the base. There are many types of bases in circulation, some of the most popular include Bayonet, Screw In and GU10s.

Bayonet is a style of light bulb cap/base, this base is locked in place by pushing down and turning clockwise. Bayonet light bulbs have two pins, double contact base and can mainly be found in the UK.

Beam Angle refers to the spread of light that comes from a spotlight style light bulb. The most popular beam angle is 36 degree (medium beam angle suitable for most purposes). Also available in spot (12-13 degree) and flood (60 degree).

We offer various beam angles in GU10, MR16 and PAR light bulb styles.

Biax® is a trademark of GE lighting. These light bulbs have a straight tube that is bent back in the middle, constituting a biaxial tube. Biax® light bulbs come in Biax® L, Biax® T, Biax® D and Biax® S variations.

Blacklight light bulbs and fluorescent tubes are mainly used in Fly Killer/Zapper Units. Other uses of these include industrial processes and special effects. The UV light produced from these lamps peaks at around 350-356 nanometers.

Blacklight Blue (BLB) is a type of UV light that has a filter to block most visible light, the remaining light enhances whites. These light bulbs and tubes can be used for many applications including oil painting/bank note authentication and dramatic lighting effects.

BLV are a German manufacturer that specialise in Metal Halide and Halogen Light Bulbs. Founded in 1968 BLV have become a trusted global player in lamp manufacturing. 

Brightness is the term used to describe the effect of luminance on an observer. The maximum brightness is said to be found in Pure White whilst the minimum is expected to be found in Pure Black.

Candela, sometimes written as cd, is a unit used to measure luminous intensity in a given direction. The term candela stemmed from wax candles of a certain dimension, which were stated to produce one candela in every direction.

Carbon Filament light bulbs are replicas of the original style 1900's lightbulb. These light bulbs are made by dipping silk in a liquid carbon mix which is then wrapped around a mandrel. These light bulbs create a warm cosy light that is popular in restaurants across the UK.

Cat 2 is a type of light fitting that has been designed for use in offices. The main reason for installing Cat 2 light fittings is to remove reflections of the luminaire (light fitting) on monitors and display screens.

A type of metal halide light bulb that uses a ceramic material for the arc tube instead of glass. This style of light bulb results in better colour rendering and brighter light.

A compact fluorescent lamp is an energy saving fluorescent lamp that has been reduced in size and uses approximately 20% of the power of a normal incandescent light bulb. These lamps are usually tubular glass, sometimes folded and work in conjunction with a electronic ballast.

COB is a form of lighting technology that can be found in LED light bulbs. COB is an acronym for Chip On Board and is the most up to date LED technology. Typically this style of lamp is manufactured from 9 or more diodes.

Here at BLT Direct we stock a wide range of COB LED light bulbs which includes LED GU10 and LED MR16 light bulbs.

CRI, sometimes written as Ra, is used to compare a light bulb/light fittings' ability to replicate the sun. An example of this would be a light bulb with a CRI rating of 80, this would mean that the light bulb is replicating 80% of the visible colour spectrum of the sun.

A further example of CRI would be if a light bulb had a 100 CRI rating. This would mean the light bulb would exactly replicate the colours of the sun on a bright day.

Colour temperature, sometimes refered to as CCT (correlated colour temperature), is simply a method of describing the colour characteristics of a light bulb. Colour temperatures range from low (warm/yellowish) type colours all the way up to high (white/bluish) light. 

Colour temperature is measured in "Kelvin" which is explained in more detail below. More information can be found on our colour temperatures example page.

A term coined by GE Lighting, Constant Color® describes a coating added to their range of Halogen MR16 Lamps. The coating is designed to enable lamps to withstand temperatures of up to 500 Degrees Celsius without depreciation of colour output.

Control Gear is a term relating to a piece of electrical equipment that limits/stabilizes current in an electrical circuit. This operation is used for reducing flickering, noise and energy consumption when running fluorescent tubes and compact fluorescent light bulbs.

The most popular items of control gear are high frequency ballasts. Also available are switch start chokes, digital ballasts and ignitors.

Cool White is the term used to describe light bulbs/fluorescent tubes that have a Kelvin rating of 4000-4500 Kelvin. Although this term is used for all types of light bulbs its official use is only for light bulbs with a CRI of 62.

Crompton Lamps LTD were founded in 1878 which makes them one of the oldest lamp businesses in the world. Today Crompton are still a UK based company that offer a large range of light bulbs which include LED Light Bulbs and LED Tubes.

Daylight light bulbs are designed reproduce the colour of natural daylight. These light bulbs have a colour temperature of 6000-6500 Kelvin.

Dichroic is a term that describes a reflector that projects most of the heat through the back of the lamp. This means that a 'cool beam' light is emitted, protecting what is being illuminated from damage. A common example of dichroic light bulbs are Halogen MR16 Lamps.

As the heat is dissipated backwards it is not recommended to use a dichroic lamp in an enclosed or recessed fitting.  

Dimmable refers to whether the lumens on a light bulb can be varied (brighter/dimmer) while still maintaining reliability. Incandescent and Halogen light bulbs are dimmable as standard, when buying Energy Saving CFL or LED light bulbs please ensure you are ordering dimmable versions.

A dimmer switch is used to control the brightness of light by changing the voltage waveform applied to the lamp, originally for halogen and incandescent lamps but recently also includes CFLs and LEDs. When selecting a dimmer for LED and CFL lamps it is important to consider the total wattage of the lamps to be controlled and select a dimmer switch that that has a lower limit of less than the total wattage of the lamps.

IE 6no. lamps x 7 watts each = 42 watts therefore a dimmer switch rated at 40-250 watts would be acceptable, Less than 6no. lamps in this example would cause flickering of the lamps 

A downlighter is a light fixture that is inserted into a drilled hole in a ceiling and gives the appearance of a light shining from a hole in the ceiling, available in halogen, energy saving and LED versions.

Dulux is a term coined by Osram to describe their range of compact fluorescent lamps. Their products include Dulux-S, Dulux-L, Dulux-D, Dulux-T and Dulux-F Lamps.

E10, or Miniature Edison Screw (MES), is a type of screw in lamp base with a 10mm diameter. Common E10 capped light bulbs include Candle Bridge and Nightlight Light Bulbs.

E11 is a type of screw in lamp base with an 11mm diameter. Some types of E11 capped light bulbs include JD Tubular Halogen and ANSI Coded Lamps.

E12, or Candelabra Edison Screw (CES) is a type of screw in lamp base with a 12mm diameter. Light Bulbs of this type are normally found in chandeliers and night lights.

E14, or Small Edison Screw (SES), is a type of screw in lamp base with a 14mm diameter. A common base amongst light bulbs, the E14 cap can be found on Candle, Golfball and Reflector Lamps.

E27, or Edison Screw (ES), is a type of screw in lamp base with a 27mm diameter. Very common, the E27 base is found on a variety of different light bulbs, including GLS, Candle and Golfball Lamps.

E40, or Giant/Goliath Edison Screw (GES) is a type of screw in lamp base with a 40mm diameter. This type of base is found on a variety of different lamps, including GLS, LED Corn, Sodium, Mercury and Metal Halide Light Bulbs.

E5, or Lilliput Edison Screw (LES), is a type of screw in lamp base with a 5mm diameter. E5 capped light bulbs are usually miniature style lamps.

Edison Screw is the term describing the screw in base developed by Thomas Edison in 1909. There are now a wide variety of different edison screw caps; E5 (LES), E10 (MES), E12 (CES), E14 (SES), E27 (ES) and E40 (GES) to name a few. The most common type of Edison Screw base is E27, which measures 27mm in diameter.

The original type of ballast, the electromagnetic ballast was introduced with the first iteration of fluorescent lamps.

An electronic transformer is used to reduce mains voltage to a suitable voltage for halogen light bulbs (Not to be confused with LED Drivers). When selecting a transformer it is important to ensure the max wattage is not exceeded by the total wattage consumed by the light bulbs.

Please Note: It is not recommended to "max" out transformers.

IE 5no. lamps x 10 watts each = 50 watts therefore a 60 watt (60VA) transformer would be acceptable, however if you had 6 lamps a 60 watt transformer would be "maxed" out. In this case we would then recommend a 105 watt (105VA) model.

Festoon Lamps are a type of double ended miniature incandescent bulb commonly used in Automotive lighting applications.

Fire Rated Downlights maintain the protection a ceiling gives from fire and prevents smoke and/or flames from passing through. Therefore to comply with building regulations fire rated downlights are required on the ground floor.

Fire Rated Downlights are available in 30, 60 and 90 minute versions. 

Fluorescence is a form of luminescence that emits light by way of absorbed electromagnetic radiation, mainly light. Fluorescence is usually found in Fluorescent Tubes and Compact Fluorescent Lamps.

Full Spectrum is a term used to describe light bulbs and fluorescent tubes that replicate natural daylight. Officially full spectrum should only be related to light bulbs and tubes that have a 90+ CRI. 

G10q is a type of 4 pin lamp base that is commonly found on T9 Circular Fluorescent Tubes. The G10q base is usually located on the inside of the tube and has square positioning.

G12 is a type of lamp base with 2 pins 12mm apart. The G12 base is usually found on Tubular Metal Halide lamps. Some common G12 capped light bulbs are the HQI-T (quartz) and CDM-T (ceramic) lamps.

G125 refers to a type of Globe shaped light bulb with a 125mm diameter. The G125 shaped light bulb is available in Incandescent and LED versions.

G13 is a type of lamp base found on T8 or T12n Fluorescent Tubes. The G13 cap has a 13mm gap between 2 pins found at either end.

G23 is a type of lamp base that is found on PLS compact fluorescent lamps, Sylvania Lynx S, Ge Biax S and Osram Dulux S Lamps. The pins are 23mm apart and have a small square peg between them.

G24d-1 is the type of base found on 10 or 13 watt PLC Compact FluorescentSylvania Lynx-DOsram Dulux D and GE Biax D Lamps with 2 pins and 2 dowels in left to right alignment. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

G24d-2 is the type of base found on 18 watt PLC Compact FluorescentSylvania Lynx-DOsram Dulux D and GE Biax D Lamps with 2 pins and 2 dowels in left to right alignment. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

G24d-3 is the type of base found on 26 watt PLC Compact FluorescentSylvania Lynx-DOsram Dulux D and GE Biax D Lamps with 2 pins and 2 dowels in right to left alignment. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

G24Q-1 is the type of base found on 10 or 13 watt PLC Compact FluorescentSylvania Lynx-DEOsram Dulux D/E and GE Biax D/E Lamps with 4 pins and 2 dowels in middle alignment. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

G24Q-2 is the type of base found on 18 watt PLC Compact FluorescentSylvania Lynx-DEOsram Dulux D/E and GE Biax D/E Lamps with 4 pins and 2 dowels in left to right alignment. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

G24Q-3 is the type of base found on 26 watt PLC Compact Fluorescent, Sylvania Lynx-DEOsram Dulux D/E and GE Biax D/E Lamps with 4 pins and 2 dowels in right to left alignment. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

G4 is a type of lamp base that has two small pins 4mm apart, originally developed for halogen capsule lamps, and also in recently released in versions of led G4 capsule lamps 

G5 is a type of lamp base found on T4 or T5 Fluorescent Tubes. The G5 cap has a 5mm gap between 2 pins found at either end.

G6.35 is a type of lamp base that has 2 small pins 6.35mm apart originally developed for halogen capsule lamps, however can also be found on G6.35 capped Photgraphic and Projector Lamps.

G9 is a type of lamp base that has two small pins or loops of wire 9mm apart originally developed for Halogen Capsule Lamps and now also found on LED G9 Capsule Lamps.

G95 refers to a type of Globe shaped light bulb with a 95mm diameter. The G95 shaped light bulb is available in Incandescent and LED versions.

Gang is a term used to describe the number light switches or sockets grouped together on one face plate. For example a 2 gang socket will be able to take 2 plugs and a 2 gang light switch will have 2 rocker/rotary switches.

GE, or General Electric was founded back in 1911 and has since become one of the leading manufacturers in lighting products. Some of their more popular products include Compact Fluorescent Lamps and Fluorescent Tubes.

A Germicidal Lamp is a specialist lamp that produces a short wave ultraviolet light that destroys bacteria. These can be used to produce ozone for water filtering and in air conditioning units.

Glare is a term used to describe the visual impairment caused by excessive brightness. Glare can be divided into discomfort glare and disability glare. Discomfort Glare is when a light source in the field of view causes an instinctive need to look away due to overall illumination being too bright. Disability glare is where a light source outside of the field of view causes reduced visibility inside the field of view.

GLS, or General Lighting Service refers to the traditional standard light bulb shape. GLS Light Bulbs come in a range of different wattages, with halogen, energy saving and LED GLS Light Bulbs also available.

GR10q is a type of 4 pinned lamp base found on 2D compact fluorescent lamps of 10, 16, 21, 28 and 38 watt ratings. The GR10q base is distinguishable by the 10mm gap between the square positioned pins.

GR8 is a type of 2 pinned lamp base found on 2D compact fluorescent lamps of 16, 18 and 28 watt ratings. The GR8 base is distinguishable by the 8mm gap between the pins.

The GU10 base is distinguishable by the 2 pins 10mm apart and 'twist and lock' installation. The most popular light bulb of this type is the Halogen 50 Watt Standard GU10 Lamp, however energy saving and LED GU10 Light Bulbs are also available.

The GU4/GZ4 base is found on MR8 and MR11 Light Bulbs with 2 pins each 4mm apart. The difference between the GU4 and GZ4 bases is that on the former there will be a distinguishable channel on one or both sides of the base, making a GZ4 capped lamp impossible for use in a GU4 lamp holder and a GU4 capped lamp suitable for both types of lamp holder.

GX24D-1 is the type of base found on 13 watt PLT Compact Fluorescent, Osram Dulux T and GE Biax T Lamps with 2 pins and 2 dowels in middle alignment. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

GX24D-2 is the type of base found on 18 watt PLT Compact Fluorescent, Sylvania Lynx TOsram Dulux T and GE Biax T Lamps with 2 pins and 2 dowels in a left to right alignment. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

GX24D-3 is the type of base found on 26 watt PLT Compact FluorescentSylvania Lynx TOsram Dulux T and GE Biax T Lamps with 2 pins and 2 dowels in a right to left alignment. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

GX24Q-1 is the type of base found on 13 watt PLT Compact FluorescentOsram Dulux T/E and GE Biax T/E Lamps with 4 pins and 2 dowels in middle alignment. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

GX24Q-2 is the type of base found on 18 watt PLT Compact FluorescentSylvania Lynx TEOsram Dulux T/E and GE Biax T/E Lamps with 4 pins and 2 dowels in left to right alignment. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

GX24Q-3 is the type of base found on 26 watt PLT Compact FluorescentSylvania Lynx TEOsram Dulux T/E and GE Biax T/E Lamps with 4 pins and 2 dowels in right to left alignment. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

GX24Q-4 is the type of base found on 32 or 42 watt PLT Compact FluorescentSylvania Lynx TEOsram Dulux T/E and GE Biax T/E Lamps with 4 pins and 4 dowels in a square arrangement. For more exact information on dowel positioning please refer to our FAQ page on Compact Fluorescent Plastic Lug Orientation.

GU5.3 and GX5.3 caps are types of lamp base with two pins 5.3mm apart. Commonly found on MR16 Light Bulbs, these bases differ due to the GU5.3 cap having an indent on either side of the base. This indent means that only GU5.3 capped lamps can be used in GU5.3 lamp holders.

GX53 is a type of lamp base with 2 prongs 53mm apart. A GX53 base is usually found on an Disc Light Bulb, available in CFL or LED versions.

A GZ10 base is a variation of the GU10 base that has squared edges rather than rounded. As a result of having a squared base, a GZ10 Lamp cannot be used in a GU10 fitting whereas the latter can be used in either.

GZ10 lamps are usually dichroic, meaning most of the heat emitted from the lamp is projected backwards into the fitting.

A halogen lamp, sometimes called quartz or tungsten halogen, is a type of incandescent light source that uses a gas from the halogen element group to give a higher output and longer life span. Some common types of halogen light bulbs include GU10 Lamps and MR16 Light Bulbs.

High Intensity Discharge can relate to Metal Halide, Mercury and Sodium light bulbs. These light bulbs all contain tubes that enclose gasses. Discharge lamps operate at high pressure and also run very hot.

High Bay light fittings are generally found in warehouse environments. These fittings should only be used in locations with a ceiling/roof height above 25 feet. 

In the past high bay lighting has been exclusively HID but recently LED High Bays have emerged.

Sodium light bulbs are part of the high intensity discharge family. These lamps produce light by passing an electrical discharge through a tube containing sodium vapour.

Sodium light bulbs run at high pressures and temperatures.

Ignitors provide a high voltage pulse to begin an electrical discharge. This discharge when paired with a compatible ballast then illuminates Metal Halide, Mercury and Sodium discharge lamps.

Ignitors come in various models including "super imposed", "timed super imposed" and "pulse" versions.

Incandescence is a term used to describe visible light emission as a result of high temperatures. Incandescence can be witnessed in the operation of Incandescent Light Bulbs, in which the filament glows red hot to emit light.

In lighting Incandescent describes a type of light bulb that heats a wire filament till it glows by passing an electrical current through it. These lamps come in a variety of styles, such as Incandescent GLS and Candle Light Bulbs.

Infrared lamps give off infrared radiation outside the wavelength of visible light, however the heat given off is still felt. These lamps can be used for Zone Heating, Catering, Animal Husbandry, Industrial Processing and Medical applications. One of the applications for these light bulbs is outdoor patio heaters.

Infrared lamps are available in Clear, Ruby and Gold glass finishes. Please note the finish of an infrared light bulb is purely cosmetic.

Instant Start is the term used to describe the instantaneous ignition of a light bulb. The term can be used in reference to Control Gear and LED Light Bulbs.

Integral are a manufacturer that specialises in innovative and efficient LED Lighting Products. Some of the more popular Integral products are Dimmable LED Candles and LED Gollfballs.

The IP, or Ingress Protection rating of a lighting product describes how well protected it is against dust, accidental contact and water. This is usually displayed as the letters IP followed by 2 digits, the first (ranging from 0-6) denoting the contact and dust protection, and the second (ranging from 0-8) describing the water protection.

IP20 is an Ingress Protection rating that provides low intrusion protection dust and no moisture protection. The first digit explains intrusion protection (2=against fingers or similar sized objects) and the second digit explains moisture protection (0=no protection).

IP44 is an Ingress Protection rating that provides good intrusion and moisture protection. The first digit explains intrusion protection (4=protection against small tools) and the second digit explains moisture protection (4=protected against water spray in all direction).

IP65 is an Ingress Protection rating that provides complete protection against dust and has great protection against moisture. The first digit explains intrusion protection (6=completely dust tight) and the second digit explains moisture protection (5=low pressure water jet protection in all directions).

IP68 is an Ingress Protection rating that provides complete protection against dust and moisture. The first digit explains intrusion protection (6=completely dust tight) and the second digit explains moisture protection (8=protected against prolonged effects of immersion under pressure).

Kelvin is a term used to describe the colour temperature, often displayed as just the letter K. Some common colour temperatures are 2700K, 3000K and 6500K, which relate to Very Warm White, Warm White and Daylight Light Bulbs.

Kilowatt is simply the measure of 1000 watts. When working out savings on our LED and Energy Saving products we refer to kWh which is the typical billing unit used by utility companies in the UK. 

An example of kWh would be if a 50w lamp operated for 20 hours (50w x 20 hours) it would consume 1000 watts, this would equate to one kilowatt-hour.

Kosnic Lighting Ltd is a leading brand established in 2002 that produces energy saving and LED lighting products. Their popular range now includes over 700 different lighting products.

Light Center Length refers to the distance from center of the filament to the bottom of the lamp base. Please note that on different types of lamps the reference point for the bottom of the base can change.

An LED Driver is designed to regulate the power to LED light bulbs. The difference between an LED Driver and conventional power supplies is that the LED Driver is continuously responds to the changing needs of the LED.

LED, or Light Emitting Diode is the term used to describe a semiconductor diode that emits light once an electrical current passes through it. In lighting, LED Light Bulbs are a leading energy saving alternative to conventional Halogen or Incandescent Lamps.

Lumen Maintenance is the term used to describe the time a lamp takes to depreciate to a certain percentage of the total lumen output. For example if a light bulb has a L80 rating of 15,000 hours, after the 15,000 hours mark the lamp will have reached 80% of its' total lumens.

Replacing wattage as the standard unit of brightness, Lumens is a new measure introduced with the arrival of energy saving and LED Light Bulbs. This was due to these types of bulbs being able to emit the same amount of light as conventional equivalents, with a greatly reduced power consumption.

A luminaire is simply a complete electronic light fitting. Luminaires are hollow fittings that take light bulbs or fluorescent tubes. Some luminaries can be configured with reflectors (directional light) or outer shells (anti corrosive for protection from the elements).

Luminaires are not to be confused with more portable light fittings like table/desk lamps.

Unlike in fluorescence, luminescence describes the emission of light from a substance that is relatively cool. In Lighting Luminescence is caused electrical energy or chemical reactions. An example of luminescence can be found in LED Light Bulbs, which are often described as cool running.

Lux is simply a unit of illuminance. The higher the lux level the more lumens per square meter.

Lynx is a term coined by Havells Sylvania to describe their range of compact fluorescent lamps. Their products include Lynx-L, Lynx-S and Lynx-D Lamps.

A term used in relation to emergency lighting, maintained describes an emergency luminaire that is continuously lit, even in the event of power loss.

A UK based manufacturer founded in 1994, Megaman have quickly established themselves as a leading brand in the lighting industry. Their success started when they manufactured the world's first CFL GU10 Lamp in 2002.

Mercury light bulbs are a type of discharge lamp, this type of light bulb works by producing radiation from excited mercury vapor. The majority of Mercury lamps give off a white light but they are also available in blacklight blue versions.

Metal Halide bulbs are a hybrid of Mercury and Sodium light bulbs. These light bulbs may also contain halides of metals including scandium, indium and dysprosium. 

Monopin is a term used is reference to fluorescent tubes. As its' name states, the monopin fluorescent tubes have only one pin at each end. Designed for specialist applications, monopin tubes are normally only used in explosion proof fixtures.

MR11 describes a type of Multifaceted Reflector that is 11 eighths of an inch in diameter, or 35mm. MR11 light bulbs are commonly found in low voltage decorative and spotlighting applications.

MR16 refers to a Multifaceted Reflector that is 16 eighths of an inch in diameter, or 50mm. MR16 can be used to describe GU10 Lamps, although it is more commonly used to describe 12V GU5.3 Capped Light Bulbs.

MR8 describes a type of Multifaceted Reflector that is 8 eighths of an inch in diameter, or 25mm. MR8 light bulbs are commonly found in low voltage decorative and spotlighting applications.

A term used in relation to emergency lighting, non-maintained describes an emergency luminaire that only reacts and turns on in the event of power loss.

Northlight is a term used to describe full spectrum fluorescent tubes. These tubes are designed to offer almost perfect colour rendering of over 90Ra, replicating the look of daylight. Applications for northlight tubes vary from specialist design to retail display lighting.

Some lamps are position orientated and have been designed to operate at a certain position. As a result their ratings for these types of lamps have been based on operation in this position. 
Burning position orientated lamps in a position different than intended can seriously hamper lamp life, lumen output and colour.

One of the leading names in the industry, Osram has throughout the years become a household name for lighting. They are particularly well known for their Compact Fluorescent Lamps and Fluorescent Tubes.

A PAR lamp, or parabolic aluminized reflector lamp, is a type of reflector lamp found in indoor environments and outdoor in weatherproof fittings. PAR Lamps are distinguished by their diameter, for example a PAR16 lamp is 16 eighths of an inch in diameter, or 50mm. The approximate diameter in mm can also be found by multiplying the PAR number by 3.175, for example a PAR38 is 120mm in diameter (38x3.175=120).

A Pendant Light is a common type of single light fitting that hangs down from the ceiling. Pendant lights usually hang on a chain, rod or cord and are designed to bring light from the ceiling closer to where it is needed the most.

A household name, Philips are a brand renown for their high quality products. Some of the more well known Philips products are their Metal Halide Lamps, Control Gear and Fluorescent Tubes.

The letters' PL stand for Philips Lighting, and are commonly used in association with the letters; T, C, L or S to describe their range of compact fluorescent lamps. PL-L usually stands for Long Single Turn, PL-C (or sometimes D) stands for Compact Double Turn, PL-S stands for Single Turn and PL-T stands for Triple Turn.

Phosphor is a term generally used to describe a substance that emits light when exposed to radiation such as ultraviolet, through a process called luminescence. Phosphor layers provide most of the light emitted from fluorescent tubes and CFL's, and phosphor is often used as a coat for stabilising the output of metal halide lamps.

Photocell is a term used to describe a sensor which detects light. In lighting a photocell sensor is sometimes referred to as a day and night sensor. The photocell sensor detects when light falls below a certain level to activate, and automatically turns off when light has risen back above a certain level.

PIR, or Passive Infrared, refers to a sensor designed to detect movement. A PIR sensor functions by measuring infrared radiation in its' field of view and detecting when something breaks into this view.

Passive is used to describe the sensor as it does not emit an infrared beam, merely detects infrared given off by sources. 

A term coined by GE Lighting for their specialist range of MR16 Halogen Light Bulbs. The Precise™ Lamps have been designed to offer precise beam control and consistent crisp white light throughout their lifespans.

A manufacturer with over 40 years of lighting industry experience. Cost effective without compromising on quality, some highlights from Prolite are their Energy Saving Spirals and LED G9 Capsules.

Pygmy is a term used to describe the shape of a light bulb. With small dimensions, pygmy shaped lamps are usually found in Decorative or Space Limiting applications. Incandescent and LED versions are available.

A type of metal halide light bulb that uses a quartz material for the arc tube instead of ceramic. This style of light bulb uses reliable, tried and tested technology and is available in a wide range of wattages.

R7s and RX7s are two types of double ended lamp base. The R7s base is commonly found on Halogen Linear Light Bulbs whereas the RX7s is normally found on Metal Halide Lamps.

RGB refers to the colours Red, Green and Blue. At BLT Direct we use RGB to describe colour changing light bulbs, for example our RGB LED Light Bulbs.

Small Bayonet Cap, or SBC, is a common lamp base with a 15mm diameter. The Small Bayonet Cap has 2 pins which twist and lock into the lamp holder. SBC Light Bulbs include Candle, Golfball and Pygmy Light Bulbs.

An initialism for Surface Mounted Diode, SMD refers to mounted LED chips on PCB (Printed Circuit Board). Surface Mounted LED's were one of the first iterations of LED Light Bulbs.

ST64 is a term describing the shape of a light bulb, often referred to as a squirrel cage or pear shape. The ST64 shape has a diameter of 64mm and is commonly found containing Squirrel Cage or LED Filaments.

A starter is used in the operation of fluorescent tubes. The starter is designed to preheat the electrodes in a fluorescent tube and produce an ignition pulse to light it up. While the tube is lit, a starter consumes almost no power and will be ready to function again as soon as the tubes have been turned off.

Havells Sylvania were founded in 1901 and have been a brand synonymous with quality. They are particularly well known for their Compact Fluorescent Lamps, Fluorescent Tubes and Halogen Light Bulbs.

A T12 Tube is a type of fluorescent tube commonly found lighting larger areas such as offices and retail spaces. The T12 Tube was one of the first fluorescent tubes to be manufactured, however is now being phased out in favour of the more efficient T8 Tube which has the same G13 base. T12 Tubes measure 38mm, or 12 eighths of an inch, in diameter and are available in wattages ranging from 20-125 watts.

T2 is a term describing a tube that is 2 eighths of an inch in diameter, or 7mm.

A T2 Tube is a type of slimline fluorescent tube commonly used for Cabinet and Display lighting. Available in 6, 8, 11 or 13 watts the T2 tube has a distinguishable W4.3 Plug In base at each end.

T2 can also be used to describe certain types of energy saving lamps, such as Energy Saving Spirals

A T4 Tube is a type of fluorescent tube commonly found in pelmet or under cabinet lighting due to their slimline design. The T4 tube is named so as it measures 4 eighths of an inch, or 14mm in diameter and is available in wattages ranging from 6 to 30 watts.

A T5, sometimes called the T16 is a common type of fluorescent tube predominantly found in recessed and suspended ceiling applications. The T5 tube gets its' name from being 5 eighths of an inch in diameter, or 15-16mm.

Although commonly referring to linear tubes, T5 tube could refer to a type of circular fluorescent tube. The T5 circular tube has a 2GX13 base with 2 pins either side of the tube.

T5 can also be used to describe 2D Compact Fluorescent Lamps. This is due to the diameter of the actual tube itself being 15mm, the same as the T5 Linear Tube.

A T8 Tube is a type of popular type of fluorescent tube favoured for its' versatility in application. The T8 tube is named so as it measures 8 eights of an inch in diameter, or 25mm.
T8 Fluorescent Tubes can now be replaced with LED alternatives, offering a longer life span and reduced power consumption.

A T9 Tube is a type of circular fluorescent tube often found in Insect-O-Cutor Units and Circular Luminaires. The T9 Tube has a 29mm, or 9 eighths of an inch, diameter tube and G10q base which has 4 pins in a square on the inside of the tube.

USB, or Universal Serial Bus, is a term used to describe the industry standard for connecting peripherals to computers and other devices.

UVB makes up one half of the suns UV rays. UVB can be produced by specialist light bulbs and tubes, these lamps are designed for use with reptiles.

Desert Reptiles: 10-12% UVB
Rainforest Reptiles: 5% UVB
Other Reptiles: 2% 

Verbatim Europe have only recently launched their range of LED Lighting, originally specialising in storage media. Offering high quality LED products, their range includes LED Candles, LED Globes, LED Golfballs, LED PAR38's, LED Tubes and LED Luminaires.

Voltage is the measurement of electrical potential. The majority of light bulbs in the UK run on 220-240 volts.

It is important to keep in mind that some light fittings/light bulbs require a low voltage source, therefore a transformer would be required to "step" down the volts.

W4.3 is a type of plug in cap found commonly on T2 Fluorescent Tubes.

Wedge Base is a term used to describe low voltage capless capsule lamps. These lamps are commonly used in Garden, Automotive and Bicycle lighting applications.