A guide to lamps for recessed lighting
Recessed lighting has come a long way since it first made an appearance, but which changes
have made a significant impact?
Recessed lights consist of a trim, the visible part of the light, and the housing, or fixture, which is sometimes called the lamp holder. The fixture is fitted into the ceiling or other surface. Recessed fixtures are used for background and task lighting and there are now many different types as a result of technology development, regulatory requirements and evolving consumer preferences. At the same time, light sources, reflectors and lenses specifically suited for recessed fixtures have been developed.
The parabolic aluminised reflector (PAR) lamp
Lamps for recessed lighting need to be able to direct the light if most of it is not to be wasted going up into the ceiling. The first and most common way of controlling the width of the light beam was by integrating a parabolic aluminised reflector (PAR) into the lamp. Early PAR lamps used incandescent light sources and usually had screw fittings, most commonly E14 or E27. Later, PAR lamps used halogen light sources, often with GU10 bases. The tendency for early halogen light sources to explode upon failure meant that glass covers were needed on either the lamps or the fixtures as a safety precaution.
These directional lamps are widely used in commercial, residential and transportation applications. Two standard nomenclatures were developed for them.
The first was the ‘R’ series designation – R50 denoting a lamp with a 50mm surface diameter and R63 a lamp of 63mm diameter.
The second nomenclature defines their size with respect to a PARxx designation. For example, a PAR64 lamp has a nominal 8in diameter and a PAR16 has a 2in diameter; divide the PAR number by eight to determine the size. An R50 is equivalent to PAR16 and an R63 to a PAR20.
Each size of lamp will also have a defined beam width. Wider beams are used for general lighting and narrower, more intense beams for task lighting. The beam widths are defined as very wide flood (VWFL) of 60° or more, wide flood (WFL) of 55-60°, flood (FL) of 35-40°, spot (SP) of 8-20°, narrow spot (NSP) of 8-15°, and very narrow spot (VNSP) of less than 8°. The definitions vary slightly by manufacturer.
In today’s LED lamps, a lens, which can further focus the beam, is often used. Verbatim LED PAR16 GU10 downlights only consume 4W, providing a 90% reduction in energy costs when compared to the 40W halogen lights that they replace.
The multifaceted reflector (MR) lamp
In 1965, another kind of directional lamp was developed. The multifaceted reflector (MR lamp) was originally designed for use in 35mm slide projectors. Just like PAR lamps, dividing the part reference number by eight gives the diameter of the lamp in inches. For example, an MR16 has a lamp face that is 2in across.
Most of these lamps use aluminium coatings as the reflector and until recently, virtually all of them used halogen light sources.
They are available with GU10 turn-and-lock base pins or bi-pin versions that simply plug straight in and are held in place by the force of the connector socket. Bi-pin bases are now the most common for low voltage applications where lamps are typically powered by 12V AC or DC. In directional lamps, the most common bi-pin bases are designated as GU5.3 or GX5.3, which are physically identical. Suppliers sometimes confuse the nomenclature, referring to GU10 MR16 lamps as ‘GU10 type’ and GU5.3 MR16 lamps as ‘MR16 type’ when both are in fact MR lamps; they just have different bases.
When used with halogen bulbs, these are compact, high brightness lamps but they generate a lot of heat – halogen bulbs can reach up to 200°C. This limits the life of the lamps and makes effective ventilation essential. Like PAR lamps, the beam widths may be defined using the ‘flood’ and ‘spot’ terminology but there is also an ANSI standard specifically for MR16 lamps.
Developments in LED downlights
With respect to LED lamps for residential and commercial applications, it is becoming clear that customers are perfectly satisfied with a much more limited choice of styles. This helps manufacturers drive down costs by focusing R&D effort on a relatively limited product range and then producing a few products in high volume, rather than a large number of lamps in low volumes. It also reduces inventory costs for wholesalers and distributors in the sales channel.
But how can presenting a more limited choice still satisfy customers? The answer lies in examining the similarities between the physical attributes of lamps used in recessed lighting. Although there may be many different part numbers in a given supplier’s inventory, the differences between some of them are negligible, and certainly of no significance to the majority of customers. The physical format and performance of an R63 lamp of a given illuminance specification will often be almost identical to that of the closest PAR20 or MR16 equivalent. For general lighting, most LED manufacturers are therefore just producing MR types. Ultimately, the more limited choice may actually make it easier for customers to select the most appropriate lamp for their application.
LEDs are attractive light sources as replacements for halogens in recessed lighting and their greater efficiency offers energy savings of up to 85%. Recent versions are dimmable and, in some instances, colour tuneable with the appropriate electronic controls. But high efficiency is not just about energy saving. It means that much less of the electrical energy entering the lamp is dissipated as heat, so ventilation requirements may be reduced.
However, the operating life of an LED downlight will be affected by heat, so providing plenty of ventilation is still good practice.
When properly installed, the service life of an LED directional lamp in a downlighter will typically be five to six times greater than that of the halogen equivalent. They run cooler, are more controllable, and deliver quality light for much longer than their halogen equivalents. Prices for LED lamps are coming down slowly, but even at today’s levels they represent a compelling value proposition when all factors are taken into account over the 25-year life of LED-based recessed lighting.
Jeanine Chrobak-Kando is Business Development Manager, LED EUMEA, Verbatim
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