Historically, if you wanted instant switch-on for emergency lighting and you were illuminating a large area or a long aisle, two halogen headlamps on a car battery made a lot of sense.
However, there are many occasions where a different style of luminaire would do a better job. Twin spots don’t always achieve the result you expect, so pause for a second before simply ordering one from a wholesaler.
In this review, we compare both twin spots and their alternatives.
There are two main uses for twin spot fixtures. One common application is to illuminate along aisles or the rows between tall pallets. The other is to illuminate a large area such as a factory, warehouse or even a big, open plan office.
It’s important to realise that there are national standards for the illumination level to be achieved in the case of mains failure or an emergency. Typically, these standards specify a minimum of 1 lux on an escape route and a minimum 0.5 lux anywhere in a large, open area. You often require more than this minimum level depending on the individual circumstances such as high risk, necessity to move large numbers of people etc.
Many manufacturers save you the trouble of calculating minimum lux levels by supplying spacing tables. I.e. how far apart you need to put the fixtures to achieve the required illumination levels. However, these are based on a fixed aiming position for the spotlights or luminaire.
If you adjust the spotlights, the spacing tables are no longer valid. Therefore, to verify that you are conforming to the safety standards, you need the photometric files for each spotlight. If not, how will you know your twin spots are providing the required illumination level? This applies even more if you are aiming the spotlights in different directions.
You should ask the supplier for the photometric files.
Finally, there are a few other aspects to consider. It is always better to light aisles from both directions. But you do need to make sure that the lights are above, say 3m (10ft) so they cannot cause disability glare to the staff.
If you are lighting an open area, you are unlikely to achieve the required uniformity of illumination just with twin spots alone. You should consider the addition of ceiling mounted emergency fixtures which have a wide light distribution.
The Owl is a budget range, IP65, non-maintained, twin spot. The 2.5W spotlights emit 244 lm each. These emit light over a wide angle so the Owl is more suited to open areas.
Inside, there is a simple circuit board connected to a three-cell NiCd battery pack. An unusual feature of the Owl is that inside there is a small (1cm, 0.5”) rubber balloon which equalises the pressure inside and out of this IP65 unit. This thus reduces the ‘breathing’ effect as it warms and cools.
This is a really good alternative to a twin spot. One of the most noticeable features is that in emergency mode it has a whopping 1,600 lm output. Mounted 15m high (50ft), you can achieve > 1 lux minimum with luminaire spacings of more than 40m (130ft).
Another feature is that the wall mount version can be tilted downwards at 30 degrees thus making better use of the emitted light. It is also quite small for such a powerful unit, measuring less than 250mm square (10” x 10”).
The LEDs are mounted on the finned die-cast aluminium body so they should stay cool and have a reliable long life.
There are two optical distributions; one for corridors and aisles and the other for large, open spaces.
Emergi-lite is the emergency lighting division of the global group ABB.
This IP65 HyLED has a single adjustable spot which can tilt and rotate through 360 degrees. The spotlight can also be positioned flush in the body of the luminaire. In this format, it is better looking than many of its competitors.
The spotlight emits 350 lm (3.5W) as a self-contained unit and 1,000 lm (15W) in the 230v version. The open area option has a very wide beam making it suitable for locations with a typical mounting height of 5m to 8m. There is also a corridor version with a long rectangular beam.
A useful feature for the installer is that the mounting back box is fitted with two spirit levels, at right angles to each other, so that you can obtain precise orientation.
This is another luminaire which is a much better alternative to a twin spot.
There are two versions. One has a rectangular beam and is used for corridors and warehouse aisles. The other is symmetrical and used in large open areas.
It is fully featured and has an aluminium body, charge and status LEDs, and is fully addressable. It is even kite-marked as evidence of its quality.
It is also extremely compact, measuring just 100mm in diameter by 65mm high (4” x 2.5”). It weighs just 100g (3.5oz).
The catalogue includes spacing data, at various mounting heights up to 8m, to achieve 0.5 or 1 lux minimums. Its compact size means that the lumen output is less than some models but the NFW89 is very unobtrusive in appearance and the easy to understand design tables mean that it should find a lot of applications.
The IP65 CT6S is a simple, non-maintained, twin spot solution for emergency lighting applications. The only connection required is a permanent live plus a neutral and earth.
It is available in two versions, a non-maintained with standard three-hour emergency operation or a non-maintained with three-hour Dali self-test operation.
Unlike some cheaper models on the market, it is kite-marked and has ENEC-certified control gear. The CT6S is a well made, budget emergency lighting luminaire. It has NiCd batteries, deep discharge protection and the 6W twin spots emit 610 lumens.
Liteplan can supply photometric data files for the individually adjustable spotlights.
This IP65 unit is different in appearance because the large, adjustable spotlights are mounted on the front face. The spotlights have eyeball mountings are held in place with a friction fit.
It’s a well-made, solidly constructed unit with plenty of power and protection for the electronics and LEDs.
The beam from the spotlights is extremely uniform without any of the striations you get with cheaper products. It emits up to 3,500 lm, so it’s plenty for a large open area.
It’s a real pleasure to receive a solidly-constructed luminaire that works well and is supplied with all the technical data and a comprehensive instruction sheet.
The spotlights are adjustable for tilt and rotation and can be locked in position. They are 6W each so there is plenty of light for most applications. The flame retardant ABS housing is much more solidly constructed than many others on the market.
There is a log sheet, status indicator sticker, and even some simple guidance notes on how to make sure your installation complies.
It’s everything you would want from a twin spot.
This has a much lower wattage, just 1W, than most emergency luminaires on the market but it has surprisingly good performance. This is due to the lensed optical system which is available in three versions.
As well as an open area and corridor versions, there is also a narrow beam for higher mounting heights. Tamlite supplies easy-to-understand spacing tables so you can design your emergency luminaire layout quickly and accurately.
The 1W version is designed for ceiling heights up to 3-4m (10-13ft). There is also a 5W version which is designed for heights up to 16m (52ft).
Lux’s next free-to-attend Emergency Lighting Conference takes place in the Escape Zone at the LuxLive 2018 exhibition. The show takes place on Wednesday 14 November and Thursday 15 November 2018 at ExCeL London. Entry is free if you pre-register HERE.