REVIEWED Impact-resistant luminaires

Sometimes, you need a really tough luminaire. One that will resist heavy knocks or attack by vandals. Steel or aluminium are common for the bodies but sometimes polycarbonate is used. Of course, for the lens, you need a highly transmissive material and all the products here use polycarbonate. Although acrylic has better light transmittance and UV resistance, it isn’t nearly so tough as polycarbonate. Acrylic also burns more freely.

Rating system
We are all familiar with the two-digit IP rating system against the ingress of water, solid objects or dust. Sometimes a third digit was added to denote impact resistance, but this was not universally applied nor fully understood. As a result, the IEC agreed on the IK rating system and the third IP digit rating is now obsolete.

The standard for electrical equipment enclosures, including luminaires, is EN 62262. This classifies the equipment’s resistance to external mechanical shocks. Impact energy is measured in joules.

For small impacts, the test is usually done with a spring-loaded hammer. Higher impacts are tested with a pendulum or free-falling hammer. Low IK ratings need not concern us. For any kind of serious resistance, you need at least IK08. However, even IK10 isn’t that severe – it's equivalent to dropping 5kg from 400mm.

Hammer tests
As a result, some manufacturers use IK ratings based on EN 60068-2-75, which covers hammer tests. These test figures can be extrapolated to give IK ratings higher than 10 (e.g. the Designplan fitting below).

When you are comparing luminaires, it is always worth checking that the lumen output quoted is for the light actually emitted. Some manufacturers publish what they call ‘source’ or ‘gear tray’ lumens without taking into account the losses inside the luminaire or the transmittance through the diffuser. This makes a significant difference: even a good quality diffuser will lose 20 per cent, and in some older style ones only half of the LED/lamp lumens emitted will emerge.

The lit appearance isn’t normally a problem with this kind of luminaire, but some are decidedly better than others.

We have priced for 50 units that are the closest equivalent to a 1.2m unit, approx. 30-40W. The ranges are: £ <£100, ££ < £200, £££ <£300. The luminaires vary greatly in output, so price comparisons are harder than usual. First decide what you want, then look at the price range.

You can see that the samples we received varied widely in light output and power consumption, so check the data for the actual luminaire you require.

Designplan Parkalux

Designplan has been making robust, reliable, efficient luminaires for over 50 years and this is no exception. The body is zinc-coated steel finished with a thick polyester powder coat. There is an opal polycarbonate diffuser held in place by those clever tamperproof screws – the ones with a pin in the middle so you can’t use an Allen key on them. The diffuser is semi-circular in section, so a blow is more likely to glance off and due to its distance away from the LEDs inside, the diffuser appears almost totally uniform across its whole surface. But what really sets this luminaire apart from all the others I looked at is its impact resistance. Although IK10 is the highest rating in EN62262, it only amounts to 20 joules. Typically, as mentioned earlier, the equivalent to dropping 5kg from a height of 400mm. However, Designplan's Parkalux resists five times that impact, and is rated IK14. It can withstand 100 joules – the equivalent of 10kg dropped from a metre. Now that’s what you call impact resistance. 

  • Output 4,722lm
  • Power 50W
  • Efficacy 94lm/W
  • CCT 4000K
  • IP rating 65
  • IK rating 14
  • Max ambient temp 40°
  • Price £££
  • This is a very tough luminaire

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Coughtrie Rotolux

Coughtrie is a long-established UK company, founded over 70 years ago and based in Glasgow. For all that time, its product range has concentrated on arduous environments. This is one of the company’s latest and is made from extruded aluminium with a white polyester powder coat finish. The cover can be clear or frosted polycarbonate with internal ribs. These ribs break up the direct view of the LEDs and give the appearance of a sparkling array of small points. Access to the gear tray and terminal block is through one of the end caps. It is a finely engineered product with neat finishes and joints. Its appearance would suit an office or hospital as much as a tough industrial environment. It is available in one length, 990mm.

  • Output 2,400lm
  • Power 25W
  • Efficacy 96lm/W
  • CCT 4000K
  • IP rating 65
  • IK rating 10
  • Max ambient temp 35°
  • Price £££

 

  • Attractive

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Dexeco Tanek

This is what you would expect from a solid, traditionally built, impact-resistant luminaire. It is constructed of 1.2mm Zintec steel with a thick, textured, weatherproof paint finish, and weighs almost 9kg. The rounded opal polycarbonate diffuser is 2mm thick. There are 10 vandal-resistant screws clamping the cover tight. It’s got what one of my colleagues used to call ‘heft’. Inside, there is a white steel gear tray with a single row of LEDs. It is held in place by a couple of wing nuts. At the rear is a large terminal block with screw terminals. The diffuser would work better with fluorescent lamps. It doesn’t quite diffuse the LEDs so the appearance is of a broad line of light rather than an overall glow. It is available in nominal 1.2 and 1.5m lengths.

  • Output 3,445lm
  • Power 42W
  • Efficacy 82lm/W
  • CCT 4000K
  • IP rating 65
  • IK rating 10
  • Max ambient temp 35°
  • Price £££
  • Solidly built

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Holophane HF LED

Although designed as a replacement for traditional waterproof luminaires (with an ingress protection rating of IP66), the HF LED is IK10, the same rating as most of the other fittings I looked at. It is unusual in that it is made from two sections of extruded polycarbonate and is almost triangular in section. Cable access is through one of the clear polycarbonate end caps. Removing the end cap reveals the gear tray with two runs of LEDs. The only access is through the end caps and this has the additional advantage that the gasket length is much shorter than conventional luminaires where the gasket runs the whole length of the perimeter. The clear diffuser has large, internal linear prisms running the length of the luminaire. The diffuser wraps around so light is emitted around 180 degrees.

  • Output 8,742lm
  • Power 85W
  • Efficacy 92lm/W
  • CCT 4000K
  • IP rating 66
  • IK rating 10
  • Max ambient temp 40°
  • Price £££
  • Tough – and waterproof

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NVC Greenland

At first sight, this looks like a conventional twin lamp, 1.5m, T5 luminaire. The cover is clear polycarbonate with internal longitudinal prisms and you can see what appear to be the fluorescent lamps. In fact, they are hemispherical opal covers over a line of LEDs. To misquote the TV ad: ‘I can’t believe it’s not fluorescent.’ The cover is clamped to the polycarbonate body with a row of 316 grade stainless steel over-centre clips. These have the useful facility of screw fixings so you can lock them in place. The diffuser flexes quite easily, but once it is in place and sealed, it seems solid enough. Inside, the gear tray is made of finely finished anodised aluminium and is easily removable to access the terminal block. It is available in nominal 1.2 and 1.5m lengths.

  • Output 7,845lm
  • Power 79W
  • Efficacy 99lm/W
  • CCT 5000K
  • IP rating 65
  • IK rating 10
  • Max ambient temp 25°
  • Price ££
  • Clever appearance

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Trilux Nextrema

The Nextrema is the only luminaire that looks as if it has been specifically designed for LEDs. For one thing, it is totally sealed. You cannot remove the prismed lens nor is there access to a mains terminal block. Instead, it is fitted with a Wieland weatherproof connector. It’s really quick to wire up. The body is die-cast aluminium with a gun metal grey paint finish. The rear has deep, heavy heatsink fins and the whole appearance is very robust. The internally prismed lens is just 20mm deep and the LEDs can be seen from all directions although the main cut-off is at 60-65 degrees. The impact resistance is a bit lower than the others but this is compensated for by good engineering in all other respects. It is available in one length, 1.05m.

  • Output 4,300lm
  • Power 45W
  • Efficacy 95lm/W
  • CCT 4000K
  • IP rating 66
  • IK rating 8
  • Max ambient temp 35°
  • Price ££
  • Wide range of applications

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