What I’ve learned writing product reviews

Lux technical editor Alan Tulla shares his experiences and learnings from many years of testing lighting equipment for Lux's famous reviews.

I’M OFTEN asked by manufacturers how they can get a good review and I always answer the same way: ‘Simply send me a good product’.

They don’t have to pay, or advertise, to be included in a review. I never know what the sales people are doing – Lux keep me locked away in a windowless room!
All I want is a well-made luminaire with a full and accurate data sheet. I also ask for a working sample so I can see it switched on. That’s very important. With lamps, we’ll often test them at an independent laboratory.

So what have I learnt?

The best lesson is that there is a huge choice of manufacturers producing high quality, attractive, energy efficient, long-lasting luminaires. So a big ‘thank you’ to all of them for making my life easier.

Alan gets to grips with the latest LED high bay luminaires for another Lux product review

Easily my biggest lesson from testing literally hundreds of luminaires is to read data sheets extremely carefully. If the lumen output is the same at 2700K as 6000K (for the same wattage), something is wrong. Ditto for a CRI of 70 and a CRI of >90.
In the interests of fairness, I often check with the manufacturer. Some thank me for pointing out the error; some don’t understand the question and some don’t care.

You would think by now that all manufacturers would state the light output of the luminaire. This is sometimes called ‘delivered lumens’. The output of the bare LED chips is meaningless. Of course, this figure may be 30 to 50 per cent higher than delivered lumens, thus giving a misleading impression about the performance of the fixture. I’m not a naturally cynical person but I do sometimes wonder if it’s done to obtain a sales advantage over the better quality manufacturers……

Additionally, I always check the temperature used for the testing. LEDs produce much more light (maybe 35 per cent more) at low temperatures than high. It’s why ice hotels and cold stores are always lit with LEDs. One data sheet I saw gave much higher light output than its similar quality competitors. The answer was found in small print: the test temperature was a mere 5C instead of the normal 25C. This gave the manufacturer maybe a 15 per cent advantage. If the equipment is sold from Alaska to Abu Dhabi, the better manufacturers will state the lumen output at different ambient temperatures.

A general lesson about technical data is to ask for independent laboratory results. And make sure that the report applies to the lamp or luminaire you are considering (It often doesn’t).

You should always switch lamps on. Lamps can have ‘identical’ beams, colour temperatures and colour rendering indices but often appear quite different. Similarly, always try them with the actual dimmer you want to use.

Alan checks out an LED spotlight from a reputable manufacturer. However, he warns that some firms quote source lumens, not delivered lumens.

What could be simpler than a label? Every electrical safety standard across the world requires that the luminaire is correctly labelled. It is a basic requirement of CE marking and UL listing.
Some luminaires I have received as samples didn’t even have the earth, live and neutral labelled. It’s easy to understand what to do when the other side of the terminals has a yellow and green, brown and blue wire but not if all three are the same colour or are just black and white.
Wiring the incoming mains incorrectly may mean that you destroy the electronics and have to replace the luminaire but what might happen if they are wired incorrectly? In the worst case, someone could die.

Maybe the most depressing lesson is that some companies simply don’t care about their product. You would think that if you were sending a luminaire or light source for an appraisal, which will be seen by 75,000 readers across the world every month, the manufacturer would make sure it worked. Some don’t. Even when a sample is delivered by the sales representative I make sure they don’t leave until I have switched it on.

One last point is the packaging. Of course, a single luminaire is more likely to suffer being delivered in its packaging than 50 loaded on a pallet. But that is an argument for wrapping the sample luminaire more carefully. (The LuxLive product judges are regularly amazed at how poorly some products were presented).

So, in summary, my advice is: read the data sheet carefully and always look at the product switched on. And wear rubber shoes!


  • Alan Tulla is technical editor of Lux Review. He’s chairing the programme in the Escape Zone at LuxLive 2017, taking place on Wednesday 15 November and Thursday 16 November 2017 at ExCeL London. Entry is free if you pre-register HERE.