Halogen lamps are high pressure, incandescent lamps that contain halogen gases such as iodine and bromine that allow filaments to work at higher temperatures and higher efficiencies. Halogen lamps consist of a tungsten filament inside a quartz envelope that is filled with halogen gas. In halogen lamps, the quartz envelope is closer to the filament than the glass used in conventional light bulbs. Heating the filament to a high temperature causes the tungsten atoms to evaporate and combine with the halogen gas. These heavier molecules are then deposited back on the filament surface. This recycling process increases the life of the tungsten filament and enables the halogen lamp to produce more light per units of energy. Consequently, halogen lamps are used in a variety of applications, including automobile headlights. 

The Halogen Tungsten Lamp Video Credit: EdisonTechCenter / CC BY-SA 4.0
 

Specifications

Performance

Halogen lamp performance is measured in:

• Rated average life
• Watts (W)
• Lumens
• Maximum overall length

Filament

Filament designations starting with the letter "C" indicate a coiled wire filament. Filament designations starting with the letters "CC" indicate a coiled wire filament that is coiled again. The letters or numbers after the prefix indicate the positioning of the filament. Examples of filaments for halogen lamps include C-2V, C-6, C-6 Oval, C-8, CC-2V, CC-6, and CC-8. Some manufacturers depart from these naming conventions and use proprietary standards that indicate the number of watts.

Bases

Lamp bases for halogen lamps include 1” ribbon leads, 2-pin connections, 4” leads, and 6” flexible leads.

• Medium lamp bases, some of which are skirted or flared, are typically used in household lamps up to 300 W and in some mercury and sodium lamps below 100 W.
• Mogul, mogul bipost, and mogul end screw lamp bases are used in most mercury, metal halide, and sodium lamps over 300 W. Lamps requiring more than 200 V are more likely to have a mogul (or larger) base rather than a medium base.
• Double contact and candelabra double contact bases use bayonets instead of screw terminals as contacts.
• Miniature candelabras are used mostly for flashlight lamps and instrument panel lamps, typically less than 30 V.
• Miniature screw and recessed single contact lamp bases are also available. 

Standards

ANSI C78.1403 - Electric lamps - tungsten halogen lamps with G6.35, GX.35 and GY6.35 bases.

BS EN 60357 - Tungsten halogen lamps (non-vehicle) - performance specifications.

IEC 60432-2 - Incandescent lamps - safety specifications - Part 2: tungsten halogen lamps for domestic and similar lighting purposes.