Downlights are just perfect for use in bathrooms. The crisp white light from intense light sources is reflected in the highly polished surfaces and just makes the whole bathroom light and bright. If you are unsure whether to use low voltage or mains voltage lamps look at our guide at the bottom of the page.
Currently low voltage lighting particularly the 52mm dichroic lamp is experiencing a recovery from the drop off in business caused by the emergence of its 240v counterpart (often called GU10 after its lampholder design).
The difference between the 12v dichroic lamp and the mains GU10 lamp are:
Heat
The dichroic lamp is so called because of the dichroic filter applied to the back of the glass. This filter allows 60% of the heat and part of the red part of the spectrum to pass through the filter.
The GU10 mains lamp normally has a polished silver reflector so all the heat and all the light goes forward. This can be a problem in low ceiling areas as the lighting heats the room and heat the head.
Beam angles
By changing the shape of the reflector, and moving the position of the filament beam angles from 60 to 600 are available with low voltage lamps. The GU10 filament is 20 times longer than the low voltage filament so the capsule is bigger in size and this means there are no options for beam angles with GU10 lamps they are all around 380.
Lamp life
In a halogen lamp tungsten evaporates from the filament and becomes airborne. In a traditional mains lamp this appears as a blackening in the lamp. With halogen lamps (both mains and low voltage) this is collected by the halogen gas and deposited back on the filament. However with a mains lamp the filament is 20 times longer and often double wound so the tungsten can be deposited in a random fashion whereas the tungsten is deposited back onto the smaller filament more evenly. This means longer lamp life.
Colour
Closely related to the above lamp life is lamp colour. To make a tungsten filament burn with a brighter white the capsule is pressurised. This pressure is often lower in GU10 lamps to reduce the amount of tungsten that vaporizes from the filament. Some manufacturers also make the filament slighting longer to keep the temperature down which results in a warmer light closer to traditional incandescent.
Supply
Not really a feature of the lamp but this is a relevant section to highlight one major drawback with the GU10, PAR, and other mains tungsten lamps. Large mains filaments squashed into small lamps have a tendency to short circuit when the “blows”. In homes with modern wiring this often leads to the MCB being tripped. In older homes this often blows a fuse at the fuse board. This is more of an issue if the home is plunged into darkness and you cannot find the fuseboard.
Low voltage lamps are not wired directly to the mains. When a low voltage lamp fails it is extremely rare for the MCB or fused to blow as the lamp is supplied by the secondary feed from a transformer.
The history of low voltage lighting
Low voltage lighting started its life in the automotive industry out of necessity. Candles and carriage lamps were no longer practical as technology advanced and a new source of light was required to illuminate the path of the horseless carriage. As vehicles use DC batteries and an alternator to provide electricity to the assorted circuits the lighting would need to operate on a supply voltage between 9 and 13.5 Volts.
But being forced down the route of low voltage lighting had some merits in particular the length of the filament. Put simply the filament (the coiled wire within the lamp) in a 240v lamp is 20 times longer than a 12v filament providing the same wattage. This means low volt lamps can be smaller than mains lamps and provide the opportunity to have greater control of the light through optics. So, through reflector design and the use of lenses, light can be directed in a particular direction, with a selected beam (or cone) of light to provide a specific type of light.
So having conquered the automotive industry the next large scale use of low voltage lamps was traffic lights. The lamp used was a 24v capsule lamp built into a highly polished aluminium reflector with a pressed glass lens to the front. The irony of this is that many people who do not understand lighting complain that low voltage lighting is unreliable – a view obviously not shared by the Ministry of Transport who continue to use low voltage lamps to this day.
With widespread use of the low voltage lamps in the automotive industry it wasn’t too long before lighting designers became very interested in low voltage lamps as a way of creating light with a very precise beam for use in galleries. Around this time also a number of furniture designers became interested in using the PAR (polished aluminium reflector) lamps that was used in inexpensive stage lighting (more rock and roll than south bank!) within light fittings. Achille and Pier Giacomo built one such light back in 1962 and it is still for sale today by Flos. |
Bathroom
.jpg "Shower Downlight - Piston")
