All About Light Bulbs

• General lighting service (GLS) lamps may be clear, translucent (pearl), white, or coloured, and have a tungsten wire filament. The standard lamp has a pear, mushroom, or rounded cylinder shape. Other shapes include pointed candle lamps, compact pygmy lamps, and round golf-ball and globe lamps. Common wattages for GLS lamps are 25, 40, 60, and 100 W.
• Reflector lamps are used in spotlights. The inside of the glass is silvered to throw light forwards. They come in several sizes, in the same wattages as GLS lamps.
• Compact fluorescent lamps (CFLs) contain small fluorescent tubes instead of a filament, and use much less electricity than a GLS lamp for the same light output. They come in several shapes, with wattages from 3 W to 26 W (equivalent to GLS lamps rated from 25 W to 150 W).
• Halogen lamps are available in mains voltage (230 V) and low-voltage (12 V) versions. The latter are powered by a transformer wired into the lighting circuit, and come in versions of 20, 35, and 50 W.
• Tubes may be filament or fluorescent. The former are used for strip lighting, while the latter provide utility lighting to work areas. Filament tube wattages range from 30 W upwards, fluorescent ones from 18 to 58 W.

End Caps

The brass-coloured end cap, where the light bulbs connect to the fittings, may be the bayonet cap (BC) or Edison screw (ES) type. Some light fittings take lamps with small versions of these end caps, known as SBC and SES.