Historically, if you wanted instant switch-on for emergency lighting and you were illuminating a large area like a factory or a long aisle in a warehouse, two halogen headlamps mounted on a car battery made a lot of sense.
Twin spots are the standard solution for these areas but I found that on some occasions a different style of luminaire would do a better job. Also, a good twin spot performs miles better than some of the budget ones. I have seen twin spots being sold for ludicrously low prices but you should just pause for a second before simply ordering something off the shelf 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 warehouse 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 is 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 down the centre line of 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If you adjust the spotlights, the spacing tables are no longer valid.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. Therefore you should ask the supplier for the photometric data files.
Finally, there are a few other aspects to consider. It’ s 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 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.
Atria | Daisalux
If you don’t need complete flexibility as to where you aim the light beams, the Atria is a much better looking alternative to a twin spot. The wall mount version can be tilted at various angles down to 30 degrees thus making better use of the emitted light than a fixed unit. It is also small for such a powerful unit, measuring less than 250mm square. One of the most noticeable features is that in emergency mode it has a whopping 1,600 lm output from the eight LEDs. The LEDs are mounted on the finned, die-cast aluminium IP43, IK04 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. The batteries are LiFePO4.
BeamLite II | Eaton
This is a twin spot designed to be mounted on the ceiling or wall. It is a neat, unobtrusive unit measuring just under 420 x 180 x 90 mm deep. What I particularly like about the BeamLite is that you can angle the spotlights and rotate them in just about any direction. There is a narrow beam version for long corridors and aisles and another wide-angle version for open areas. A neat feature is that the spotlights can be locked in to position. At just 4.5W total, the two heads produce a highly efficient 800lm. This IP65, IK07 unit is made of polycarbonate so it is tough and resists the 850C glow wire test. There is also the option of a wire enclosure to protect it from accidental knocks. Eaton has a similar unit which is designed to be recessed called the BeamTech.
Emergency Lighting Products | TwinLED
ELP offers a variety of twin spots and the TwinLED is the IP20 basic version. The heads and main enclosure are made of polycarbonate. The batteries are NiCd. Each projector head is 3W, 5000K and emits 380lm. The IP65 version is higher wattage and emits 2 x 470 lm. It’s good to see that full photometry in the form of LDT files is available on request. The TwinLED can also be supplied with integral DALI/self-test gear.
Twin spot | Kosnic
Kosnic supplies this budget range twin spot in either an IP20, 3W or IP65, 7W version. The luminaire body is made of white polycarbonate and topped by two black spotlights. These are a Cool 6000K with a CRI of 70. The total light output is 470 lm and this is spread over 150 degrees so it is more suited to area lighting rather than aisles. The batteries are nickel-cadmium Ni-Cd.
Kansas IP65 | NVC
The new version of this well-established IP65 unit has just been launched; the main difference being it is fitted with Lithium Iron Phosphate (LiFePO4) batteries. The pros and con of the various battery types used for emergency lighting could fill an article by itself. Briefly, NVC say that the advantage of LiFePO4 batteries over say, nickel cadmium (NiCd), is that their design life is typically eight years instead of four. The lithium batteries also need less energy to charge. Output from the twin 3W, 6500K LEDs is 380 lumens. There is just a medium beam available (2 x 45 degrees) which cuts-off totally at 2 x 60. The body and spotlights are ABS and PC.
Odet LED | Orbik
We looked at the twin 18W LED unit. Interestingly, Orbik says there is still a market for its 20W and 55W tungsten halogen versions. The IP20 Odet is solidly constructed of Zintec-coated steel with an epoxy paint finish. IP65 versions are available and, so too, are Kitemarked versions for the non-maintained models. The 6500K LEDs have a CRI of 80 which is better than many twin spots. But the best aspect is the claimed 2 x 900 lm output. With the correct aiming, you could light a large area with the Odet. The hefty 7kg weight may be due to the steel body and use of sealed lead acid batteries. These have a rated life of five years.
Twinspot | P4
A big advantage of the P4 Twinspot is the Fastel fully automatic self-testing system. The two go together. These, together with the six-year warranty for the NiCd batteries minimises maintenance. There are wireless versions for remote monitoring and control. Each spotlight head is 4W and emits over 125 lm with a CRI of 80 so this unit is well suited to small and medium size areas. The spotlight heads, themselves, are finned aluminium with a black finish. These contain deep facetted reflectors which give a medium width beam. The IP54 body is made of fire-retardant ABS.