Major advances in LED lighting have meant it is becoming an increasingly affordable and cost-effective option, offering comparable light quality and much longer life than the incandescent, as well as delivering energy savings. LED lamps typically use 80% less energy than incandescent to produce the same light output, and also run cooler.

But not everything is rosy. In the past, the difference between two standard incandescent bulbs from different makers, ostensibly offering the similar lighting features and levels of performance, may have seemed relatively trivial. However, seemingly identical LED bulbs from two different suppliers can be separated by a chasm in terms of reliability, lifetime and light quality/consistency.

Most LED products today come with the European product conformity CE mark, but there is limited independent scrutiny that product performance claims are actually true. The result is that some very poor quality products exist. An issue specific to the UK is the slightly higher AC mains voltage of 240V; some imported products specified for operation in EU countries may not necessarily perform at their best in the UK.

Vendors need a close relationship with suppliers who are in the business for the long term and who have substantial R&D operations that embrace all the latest technologies. The latest LEDs feature increasingly low energy consumption and the gradual elimination of heatsinks, along with a reduction in the use of metal, moving to plastics and the transition to full glass bodies. This latter trend makes the devices safer, glass being an electrically safe material whereas there have been issues with the use of aluminium heatsinks placed on the outside of some products.

Testing

RS is building a wide portfolio of LED lighting solutions, marketed under its RS Pro brand. Its partner company runs its own light laboratory in the UK to ensure the LED products it delivers to the local market are up to standard. 

Every LED product line delivered into the lab will undergo a goods-in performance test process. The sample size – following EU guidance – is typically taking 20 products from a batch and running them through the test process. The company’s testing operation primarily focuses upon the performance of the LED, essentially measuring light output in terms of lumens, the colour temperature of the device and consumed energy.

The first tests undertaken are electrical, for fundamental electrical safety and basic function: A poorly designed LED lamp can bring significant risk – with the potential threat of a fire. However, the key tests carried out by the lab use large integrating spheres to perform quality checks that measure the amount of light and other light quality characteristics of the lamp under test. Using a halogen bulb as the reference light source, verified by the National Physical Laboratory for accuracy, LED products are tested within two large integrating spheres, measuring 42 and 65in, respectively. The inside of each sphere is covered with a precise reflective coating that diffuses light. Light hits the surface of the sphere and spreads evenly, enabling the recording of highly accurate measurements. Sensor-based detecting equipment inside the sphere measures the strength of the light source and transmits the data to the lab technicians. All the LED lamps are preheated before entering the sphere, and the sensors inside are regularly calibrated.

The technicians also run other tests including longevity, dimming ability and thermal output. Given the longevity of an LED lamp is usually many years, it is difficult to deliver accurate numbers: end-of-life testing typically involves the taking of data and the use of industry standard metrics to predict lifetimes. However, as part of the company’s process, all production units  are run for more than 4h as part of a post production aging test. Any problems that might lead to early failure – the so-called ‘infant mortality’ stage on the reliability ‘bathtub curve’ – are picked up at this stage.

The RS LED Selection Guide is designed to help customers choose lighting options that suit both their requirements and their budget.