Buying Guides - Light Fitting Types - Halogen Fittings
Author: Staff Writer
Published: July 26, 2011
Halogen lighting has become very popular over the last forty years, and offers a completely different set of features against tungsten filament (incandescent) and fluorescent lighting.
Alternatively, to find out more about this type of technology - read on...
Pin type Fittings
Most halogen lighting uses fittings with two pins at the base, and some incorporate a locking mechanism into this for lamp safety and security. There are also linear halogen lamps, commonly used for flood lighting, which have double ended sprung bases.
Because the tungsten halogen filaments burn hotter and brighter, this is fundamental to the way fittings are designed. The glass, for example, is made of quartz and sealed with a halogen gas to withstand higher operating temperatures. Dichroic and parabolic reflectors are used to send the heat out so it is not retained within the fitting, and to concentrate the beam.
Mains & Low Voltage Fittings
There is a large choice of fittings, in mains and low voltage, with and without reflectors.
The colour temperature is whiter than incandescent lighting, but not as cool as fluorescent lighting, making it ideal for display and accent lighting, in both domestic and retail applications. The hotter running temperatures, however mean it is inappropriate for large banks of lighting or for solely lighting large areas.
Low voltage halogen reflectors - GU4 & GU5.3
Low voltage halogen reflectors are very popular in domestic use for spotlighting and small areas of task lighting. They are also used in shops for small display areas.
The caps of these lamps are given a G prefix, denoting the pin-to-pin distance. Halogen lamps with reflectors are normally GU4 or GU5.3. They ordinarily feature a UV stop glass to protect and seal the lamp. The lamp holder is ceramic with metal contacts that are push fit, and flying leads for transformer connection. It is possible to have either individual transformers, or one transformer powering several lights.
Low Voltage Display Lighting
As the lamps are associated with these fitting types, which have their own sealed reflector, they can be used in any orientation, and so are great for downlighting, kitchen display and wire lighting systems. They are low voltage, so the fitting needs to have a transformer connected to it, either placed separately, or integral to the luminaire. These lamps are also cooler to run in terms of heat dissipation than mains voltage types
Popular Halogen Fittings
The GU4 type fitting is usually found on halogen reflector lamps that are small in size, like the 35mm and 25mm dichroic reflector lamps. These are also known as MR11 and MR8 lamps (because of their reflector diameter). The GU5.3 lamp is by far the most common type of halogen reflector. Also known as M50 as the reflector's diameter is 50mm. Halogen reflectors are available with a wide range of beam angles and wattages in each of the various fittings types.
Halogen Capsules G4, GY6.35 & G9
Halogen capsule lamps and the associated fitting types again have a G suffix (G denotes globular glass shape), with the number after it relating to the pin-to-pin distance in millimetres. These fittings have two pins.
With these types of fittings, the lamps have no reflectors. The lamp is simply a capsule, with the pins protruding at the bottom. Instead, the luminaire handles any focusing of the beam by its own reflectors, if required. Or, light can be thrown more simply for a dazzling wash. The quartz capsule can be damaged by any oils or residue from fingerprints. When handling, avoid touching the quartz glass by using a piece of paper, gloves, or by holding it by the pins. Clean any residue with isopropyl alcohol, before use.
Generally operating at 12v, with a transformer, low voltage halogen capsules offer a great quality crystal bright light in a compact lamp. These tend to have the fittings G4 and GY6.35. There are even some special types of these lamps which have a mini reflector built in that are non-dichroic.
Recently, the G9 halogen capsule is gaining in popularity, since it offers all the benefits of low voltage halogens, but at mains voltage, so there is no need for a transformer. This makes it easier to install and luminaires can be extremely compact. The pins are slightly different, being bent round on themselves, and therefore the fittings have sprung connectors instead of ceramic bases with metal-clamped holes like low voltage.
Capsule lamps have similar practical applications to reflector type halogen lamps, with the added benefit of no reflector, so luminaires can be more flexibly designed.
Mains voltage halogen reflectors GU10 and GZ10
Mains voltage halogen reflectors with GU10 and GZ10 caps do away with the need for separate wiring of transformers.
Twist & Lock Base
Lighting manufacturers Sylvania introduced these fitting types in 1996, which quickly became popular because of the ease of installation, since no additional transformers are required. Sometimes known as Hi-Spot, they have two thick round pins at the base, which each finish slightly thicker. Simply twisting and locking the lamp in place, much like a bayonet cap, ensures the lamp is secure and safe, and that optimum electrical contact is made.
Reflector Sealed Lamps
The GU10 and GZ10 lamps always have a dichroic reflector and sealed UV glass. This enables the luminaires to be compact. They do run fairly hot, so are ideal for use singly or in small groups.
With the GU10 lamp, heat is dissipated from the front of the fitting, leaving the rear of the fitting cool. This is the most common type of mains voltage reflector halogen lamp.
The GZ10 lamp is more specialised, in that heat is dissipated from the rear rather than the front, and so requires specially designed luminaires. The pins are the same, however the GZ10 features a square corner, which stops it being used in a fitting designed for a GU10 lamp, which could present an increased fire risk.
One of the most popular and easily recognised type of halogen lights; linear halogen fittings with R7s bases are commonly found in floodlighting and security luminaires. They are more suitable for use outdoors and the robust fittings help them withstand the elements, as they tend to be protected by aluminium reflectors and glass fronted lights.
History of Linear Halogens
The first versions were 1000 watts and were introduced around 1960. Now there is a whole range of wattages available, in different sizes, but their bases are much the same. Luminaires have become better designed, and are not the crude products they used to be.
The long filament is supported along the length of the glass envelope, and the round bases at either end fit into sprung contacts. Generally the luminaire has a reflector to throw the light forward. It is important for lamp life that the filament be kept horizontal, otherwise heat spots generated by the coil may shorten the lamp's life considerably. Again, avoid using bare hands to handle these lamps as the quartz glass envelope is easily degraded by oils.
This type of fitting is found on the majority of linear halogens, including some catering and heating bulbs. The standard lengths of these lamps are 78mm, 118mm and 189mm. More specialised sizes are 254mm and 350mm.
Other Halogen Fittings
There are many types of less common halogen reflector fittings that are used for equipment like slide projectors and data projectors. They have different operating voltages, and a larger than normal wattage range, even though they still may have G4 or GY6.35 (capsule lamps) or GX5.3 or GZ6.35 (reflector lamps) caps.
The reflector lamps have common ANSI (American National Standards Institute) names, like ESX, BAB, EYC, EXN and EXT, which refer to particular wattage/beam angle combinations. They can also relate to filament orientation, which may be necessary to line up with reflectors, so care must be taken always to replace like for like.
TV, Film & Stage Halogens
In addition, there are other fittings standard to TV, stage and film lighting that are not used anywhere else. These include the T type and A type lamps. T type lamps have several coils of tungsten halogen filament within one glass envelope, giving a bright light up to 650 watts, in a relatively compact lamp. The bases are heavy duty and ceramic, with two thick pins, sometimes of different thicknesses, to aid correct lamp orientation with the reflector system in the luminaire.
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