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Lightbulbs Guide
Lightbulb Efficiency
There has always been some confusion about how much light you get from the different types of light bulb and how much energy they consume.
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 normal 60 watt light bulb and they last up to eight times longer. There is no doubt at all that they save you money over the life of the lamp. A halogen bulb uses about half the energy of a conventional light bulb to generate the same amount of light.
Lightbulb types
(contain gases in a tube but have no filament). These have been around for many years and are better known as the long white tubes commonly seen in utility ceilings. Recent technology has reduced the size and improved the efficiency. Many different shapes and power options are available.
The benefits are low power consumption (around 20% of a conventional light bulb) and long life (up to 8000 hours). They are ideal for lights which need to be kept on for a long time. Many people assume fluorescent light is 'cold' but 'warm white' lamps are available which improve the colour.
(conventional filament bulbs)
These are the conventional bulbs which we all recognise 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 feeling to a room.
The disadvantage is that they are inefficient by modern standards and have a relatively short 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) and 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 direction fittings such as spot lights.
(filament bulbs containing halogen gas)
Halogen bulbs produce a very attractive light which closely resembles 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:
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 than the conventional 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.
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.
Key to Bulb Types
BC/B22 GLS bayonet cap general light service
BC/B22 GB bayonet cap golf ball
BC/B22 CNDL bayonet cap candle
SBC/B15 GB small bayonet cap golf ball
SBC/B15 CNDL small bayonet cap candle
ES/E27 GLS Edison screw general light service
ES/E27 GB Edison screw golf ball
SES/E14 GB small Edison screw golf ball
SES/E14 CNDL small Edison screw candle
MR16 12 Volt
Dichroic reflector (heat backwards)
Aluminium reflector (heat forwards)
Available in 20W, 35W, 50W
Beam angles 10° - 60°
Capsule 12 Volt
Available in 10W, 20W, 35W, 50W
G4 12 Volt Halogen Capsule
GY6.35 12 Volt Halogen Capsule
GU10 Aluminium reflector (light & heat forwards)
GZ10 Dichroic reflector (light forward, heat backwards)
Available in 35 - 50W
Beam angles 25° - 38°
G9
G9 mains voltage capsule lamps produce a halogen effect without the need for a transformer. The lamp runs directly from the mains and is dimmable.
Available in 25W, 40W, 60W, 75W
78mm linear halogen Available in 60W, 100W
118mm linear halogen Available in 150W, 200W, 300W
Available with built-in ballast with ES or BC fitment for replacement of GLS bulbs. Ideal for lights that will be left on for long periods, i.e. outside, hall or porch lights.
2D:
GR8 = 2 pin = 16W
GR10q = 4 pin = 28W, 38W
Requires special fittings with built in ballasts.
Fixed wattage cannot be changed.
PL / PLD lamps:
G24d-1, G24d-2, G24d-3 (d = duo = 2 pin)
G24q-1, G24q-2 (q = quatro = 4 pin)
Available 10 - 26W
Requires special fittings with built in ballasts.
Fixed wattage cannot be changed.
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