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Lamp Types (UK)

Symbols & Abbreviations

Lamp Types

ES - Edison Screw

BC - Bayonet Cap

SES - Small Edison Screw

SBC - Small Bayonet Cap

GLS - General Light Source - Commonly known as an incandescent lamp.


mm - Milimetres

cm - Centimetres

m - Metres

Light bulb Types (Low energy and fluorescent bulbs – Contain gases in a tube but have no filament). The new breed of compact fluorescent (or ‘low energy’) lamps will only use around 11 watts of power to generate the same light as a 60 watt light bulb.

There is no doubt at all that they can save you up to 80% on your electricity bill over the life of the lamp, which can last for up to 5 years (10,000 hours).

Naturally, if your using less electricity, you need to generate less electricity and this reduces greenhouse gases, which thin the ozone layer around the Earth.

Fluorescent lamps have no filament; they are just a tube with gases in it. Best known as the long white tubes so beloved in utility ceilings of the 1960’s and 70’s, recent technology has reduced the size and improved the efficiency. Many different shapes and power options are now available.

These lamps are ideal for lights that need to be kept on for a long time (i.e. overnight on landings or in hallways.) In the past it was felt that the fluorescent light was "cold" but with the invention of the "warm white" lamps this is no longer the case.

Incandescent light sources (Conventional filament bulbs)

These are the conventional bulbs we all recognize and their chief advantage is the colour of light they emit. Colours of objects are generally more accurate with this type of light bulb and they impart a warm feel to a room. The disadvantage is that they are inefficient by modern standards and have a relatively short lamp life (around 1000 hours).

Incandescent lamps come in a variety of shapes and sizes and have a number of different fittings:

  • Bayonet cap (BC)
  • Small Bayonet cap (SBC)
  • Edison Screw (ES or E27)
  • Small Edison Screw (SES or E14)
  • The Edison screw types are becoming more popular in the UK.

    Several different coatings are also available with the following properties:

  • Pearl is an all over frosting which diffuses the light and is best used in a light fitting with shades.
  • Clear bulbs are more attractive when used in fittings where the bulb is visible or a sparkle is required such as crystal chandeliers.
  • Reflector bulbs have a silvered surface to direct the light in a certain direction and are usually intended for directional fittings such as spotlights.

Halogen Light Sources (Filament bulbs containing halogen gas)

Halogen bulbs produce a very attractive light, closely resembling sunlight. They are more efficient than incandescent bulbs using only half the energy to produce the same light output and last twice as long.

Generally they are small lamps which generate a lot of heat so they can only be used in light fittings designed to cope with the higher temperatures.

There are two main types of halogen lamp available in the domestic market:

Low Voltage

These lamps operate on 12v which means a transformer has to be fitted either in the light fitting itself, or remotely. The advantages of the lower power are that the safer voltage enables manufacturers to produce interesting and slim designs without the need to protect against danger from higher voltages.

Transformers can be either electronic or ‘wire wound’. The newer electronic transformers are more energy efficient and smaller but more expensive that the wire wound type. Electronic transformers can be damaged by voltage ‘spikes’ in the mains supply (sometimes referred to as ‘dirty mains’).

These spikes can be caused by fluorescent lights, older motors, fridges, lift shaft motors etc.

If persistent problems occur, the use of mains voltage lighting is recommended.

Mains Voltage

This relatively new breed of lamps offers the light colour advantage of halogen without the need to house a transformer, the reflector type bulbs are known as GU10 or GZ10 and the latest small envelope non-reflector halogens are known as G9.


Most tungsten and halogen light fixtures are dimmable but only certain types of fluorescent can be dimmed.

When installing a dimmer you should check on the compatibility of the fitting with the dimming device and that the dimmer has sufficient capacity to control the load on the circuit.