The Bright Stuff Posted Apr 2014

LED lighting is a fantastic opportunity for electrical contractors, but there remains a lot of confusion about the technology. To help shed some light on the subject Peter Staniforth, Technical Manager at ML Accessories, answers some questions about LED.

Q: What kind of savings can be expected when switching to LED lights?

An installation of 50W 230V GU10 halogens can now be replaced with the same quantity of 5W LED 230V GU10 LED equivalents, with no reduction in illumination and an immediate 90% reduction in energy consumption. This is good news for the domestic user. Apply the same approach to a commercial application, for example a hotel or offices where hundreds of lighting fixtures are involved and the savings become massive. Of course the savings don't stop there as maintenance costs are also reduced dramatically. This is because most quality LED lamps are guaranteed to give an average of at least 30,000 hours life compared with the GU10 halogen of just 2,000 hours average life.

Q: What are the environmental benefits to using LED lighting?

LED lamps and luminaires are far more energy efficient offering significant environmental benefits over older technologies such as incandescent, halogen, fluorescent and discharge. Plus, with longer life than other technologies maintenance costs are reduced, as is landfill. Unlike fluorescent, metal halide and sodium, LED lamps do not attract flies and mosquitoes making the immediate environment they are installed in healthier, cleaner and more pleasant for the occupants. Furthermore, LEDs do not contain any nasty chemicals such as mercury.

Q: What is the best approach to take to ensure LED lighting can be dimmed?

LEDs are energy efficient by design. Simply using LED lamps or fixtures can help a facility meet updated building and energy requirements while reducing electrical consumption and cost. Therefore the rationale for dimming LED lamps becomes less relevant. For the same reason you control any light source- to maximize energy savings, extend system life, enhance flexibility, and provide a safe, comfortable environment for the building occupants. Regardless of the control system you choose, it is critical to work with a manufacturer who can guarantee compatibility and performance, eliminating many of the common concerns and issues that are seen with LED installations. At ML Accessories, we offer our Knightsbridge brand of dimmable LED luminaries across a wide range of applications designed to operate with most common dimming controls.

Q: LED packaging often quotes a beam angle - why is this important?

The beam angle of any lamp or luminaire refers to the measure of the spread of the light source and is simply stated in degrees. A more technical definition specifies it as the angle between those points on either side of the beam axis where intensity decreases to approximately 50% of its maximum. But beware, not all manufacturers specify beam angles in degrees but use terminology such as 'Spot', 'Medium' and 'Flood'. The use of this terminology is not consistent across all manufacturers and can lead to the wrong choices being made for an application. To make the most of your LED lamps, it is best to purchase a lamp with a specific beam angle depending on its use - or, in the case of retrofit for halogen, to ensure that the same or similar beam angle of LED lamp is chosen to the lamp being replaced.

Q: Why do some LED bulbs have 120 degree beam angles?

LED lamps that have beam angles in the 120 degree range are designed to disperse the light as much as possible in the same manner as traditional incandescent and fluorescents. LED lamps with a 120° beam angle are designed for lighting under cupboards, small rooms or where the ceiling height is low. They can also be used in most applications when replacing incandescent and fluorescent lamps.

Q: Do LED lights need a new transformer or will they work with old ones?

As technology moves on, LEDs are being built with retrofit and replacement in mind and this now includes MR16 low voltage halogen. In 99% of installations, MR16 low voltage halogen lamps are dependent on a transformer, normally an electronic high frequency AC transformer. Some MR16 LED lamps are now manufactured with the above in mind and their technology allows them to run with low voltage electronic transformers. There are a few important factors to take into consideration when deciding to retrofit LED MR16 lamps with existing transformers built for use with halogen lamps; these include the transformers minimum wattage/load requirements and operating frequency. If the minimum load requirements are not met then the transformer may shut down or fail to operate, and if the frequency is too low the lamp may flicker or cause premature failure of the lamp and/or transformer. Another specification to check is if the transformers are controlled by a dimmer as most retrofit MR16 lamps are non-dimmable. Suffice to say it is imperative before any retrofit installation to thoroughly test the compatibility of the MR16 LED lamp with the transformers installed.

Q: Is it preferable to use a low voltage circuit or a mains circuit for LED lights?

Currently all LED lamps and luminaries require a type of driver. The driver is either built into the lamp or luminaire, or is remotely situated close to it. As we mentioned above, some LED lamps are able to utilize an existing low voltage transformer to drive them. When trying to decide if to continue to use an existing low voltage circuit (MR16) or convert to mains voltage (GU10) consider the following:

• Does the circuit need to be low voltage for safety reasons?

• Was the original lighting design based on the higher lumen output gained from using MR16 low voltage?

• What condition and how old is the current low voltage installation in particular the condition of the lamp holders?

• Does the customer want to keep the existing lighting fixtures/Downlight?

If there are no safety issues with changing to mains voltage, then this will be the most reliable and flexible alternative to choose as the development of 230V GU10 LED lamps far exceeds that of low voltage MR16 LED lamps. Plus, unlike their halogen predecessors, there is little or no difference in lumen output. Many existing low voltage lighting fixtures can be converted simply by just changing the lamp holder, terminal block and removing the transformer as required.