Racking is different from most other lighting applications in that most of the illumination should be on the vertical surfaces rather than the horizontal.
The most obvious example is that you have to be able to read lettering on the racks and the printing on boxes and cartons, all of which are on a vertical plane.
Another difference is that the aisles are often narrow in proportion to the height of the racking. The aisles are almost like tall, narrow corridors. As such, the luminaires have to have a beam which has wide spacing in one direction and narrow in the other. This requirement makes luminaires for rack lighting very different from those used in other industrial and warehouse areas.
One final point is that the users of these spaces spend a lot of time looking upwards at the racking. It is important, therefore, that the luminaires produce as little glare as possible. Try to avoid any direct view of the LEDs. Most racking luminaires will have prisms or baffles to control the glare. A glare rating of UGR 22, or less, is desirable.
Most guidance recommends 150 to 200 lx on the vertical face of the racking. If you achieve this, it is highly likely that you will achieve a sufficient level of horizontal illumination in the aisles.
Remember to do your calculations with the racking in the right position and correct height. Calculating the illumination in the space as an open area will greatly underestimate the number of fittings required for racking.
Almost all racking and warehouse lighting nowadays uses LEDs because of their efficacy and long life. Their white light with colour rendering, CRI >70, is more than sufficient for these areas. Another advantage of LEDs is that they can have greater beam control and so, because they can deliver light where it is needed they can be, in effect, more efficient than high pressure sodium.
The lighting in racking areas should always be fitted with some type of switching or dimming control. Even a simple movement sensor can save a great deal of energy. A more sophisticated system uses linked luminaires with graduated dimming. The luminaires closest to the forklift operator are at full output. Luminaires nearby may be at 50 per cent and those furthest away at the end of the aisles may be dimmed to a very low level. The lighting ‘follows’ the forklift truck as it moves long the aisle.
In appearance, the Linergy is like a twin fluorescent reflector luminaire. The body is made of white painted, folded sheet steel. There are two linear ‘trough’ reflectors made of textured, zero iridescence, satin aluminium. Above each reflector is a row of LEDs enclosed by a linear prismatic cover.
It’s available in 1.2m and 1.8m (4ft and 6ft) lengths emitting approximately 16,000 (120W) and 24,000 lumens (180W) respectively. The LEDs have a colour rendering CRI >80 and are 4000K so they give a comfortable visual environment for the staff and people working in the aisles.
There is a comprehensive range of energy saving options such as movement detectors, with different angles for different mounting heights. Dali dimming is also available. A useful feature is the option of integral emergency lighting and this can be used in mounting heights up to 20m.
The major difference between the Prismaspace and the other luminaires reviewed here is that the optical assembly can be tilted to different aiming angles on site. There are twin and single versions that can be aimed independently. The lumen output ranges from 3,000 to 40,000 lm and is available in 4000K, 5700K, 70 CRI and 80CRI.
Holophane has been making prismed luminaires for over 120 years and so the optical system is top class. The prisms ensure it is low glare and give what Holophane calls ‘Volumetric illumination’ with an optimum mix of horizontal and vertical to the work surfaces.
The body is powder-coated extruded aluminium which ensures good thermal management of the LEDs. The standard luminaire is IP40 and IP65 is available as an option where you need extra protection from dust and moisture.
As you would expect, it’s available with a wide range of options for PIR, Dali, emergency lighting etc.
This has a solidly made, die-cast aluminium, powder coated body. It has a sensible beam distribution which gives wide spacing along the aisles and narrow in the other to provide good vertical illumination on the racking.
The Hi-Max is made in one size, approximately 630mm (2ft) long by 215mm (8.5”) wide and is available in 4000K, Ra 80. However, there is a wide choice of light output from 14,000 to 43,600 lm and an IP65 version is also available.
Ambient operating temperature range is +5 to 35C (41 – 95F).
At first sight, this IP65 luminaire looks like a single piece of cast aluminium. Everywhere you look, there are large fins and aluminium heat sinks. Nualight claims that the Arc 2 can operate in ambient temperatures from – 40C to +55C (- 40F to + 131F) and that certainly seems believable.
The Arc 2 range is from 68W/9,570 lm to 289W/37,700 lm. All are CRI 80 and 4000K. However, the beam does have some striations and is yellow at the edges. This might not matter in an industrial location.
Nualight claims that the Arc 2 produces a glare rating of UGR <22 but, purely subjectively, I found the unshielded, densely packed LEDs to be quite intense.
As you might expect, the Philips GentleSpace is a huge family of luminaires. For this particular application, the GentleSpace uses what the company calls the high rack optic. As you would expect, this has a narrow beam and wide in the other (16 degrees x 47 degrees). Although, like many other luminaires, you could see the bare lenses, the beam control was much better. Purely subjectively, the GentleSpace was less glaring and I suspect that this may be to do with the quality of the optics.
The aluminium IP65 body is cool running, with a powder coated finish and a glass cover lens.
When you are specifying luminaires, you need as much technical information as possible. The GentleSpace data sheet is one of the best we have seen. For example, it gives the median life at L70, L80 and L90. It states the driver failure rate, the space-to-height ratios and the luminance (objective brightness) at various viewing angles.
This is everything you’d expect from a quality luminaire manufacturer.
This range has been specifically designed for racking. The lenses have been developed and tooled by Tamlite to provide the optimum light distribution. There is a wide beam and a low-glare opal version for fairly low mounting heights, typically 3 to 4m. There are other lenses of various configurations which can successfully illuminate racking up to 18m high. The ultra-high rack lens option is a mere 15 degrees wide by 125 degrees in the lengthways direction. This enables you to have wide spacings and a very efficient, low wattage, installation.
The body, itself, is a plain aluminium extrusion painted white. Although individual luminaires have plastic end caps, a better choice is the continuous version option which enables you to have runs up to 100m long (330 ft).
Tamlite is known for its competitively priced products and the Rackline offers excellent value for a mid-market product.
Many people forget that Zumtobel makes a huge range of warehouse and industrial luminaires. The Craft family extends to luminaires which can operate in 70C (158F), oily and corrosive atmospheres and, at the opposite end of the scale, the food industry.
This IP65 unit is made of die-cast aluminium and white powder-coated. The optic has been specifically designed for warehouse aisles. This enables you to achieve the desired wide spacing with good vertical illumination.
The standard unit will operate at -40C to +55C and is available in 4000K and 6500K. Typical delivered lumen output is from 7,500 to 36,000 lm.
The design of LED luminaires is the subject of this year's Lighting Fixture Design Conference, which takes place on 20 and 21 June 2018 . Organised by Lux and LEDs magazine, the event takes place at the Cavendish Conference Centre in London. For more information and to reserve you place, click HERE.