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Metrolight & ECS

Smart Electronic HID Ballasts & Save It Easy Retrofit

Issue 40 Dec / Jan 2007/8

David Morgan reviews two energy saving products with differing results.


Metrolight Smart Electronic HID ballasts
Ballasts for HID lamps are not the most obvious candidates for a product review. But an innovative ballast that can dim HID lamps is an exciting development and well worth looking in to.
Israeli-based Metrolight has taken electronic HID ballasts to a new level since the company was formed ten years ago and their Smart ballasts are now capable of dimming both Metal Halide and SON lamps up 1,000 watts. Investors in Metrolight include Richard Branson’s Virgin Green Fund.

Although there are a wide variety of electronic HID ballasts available from many suppliers for lamps up to 150 watts, including UK based Harvard Engineering, there are very few for the higher wattages where the greatest energy savings are to be made. Metrolight focus completely on the HID niche market and does not produce any other kind of electronic lighting ballasts or transformers. The company claims to have a five year head start on the competition in this area.

For a luminaire designer, the opportunity to add a dimming feature to a new HID fixture seems to be a real advance. With a small number of ballasts the Metrolight range covers all HID lamp wattages from 20 up to 1,000 watts. Universal voltage and both UL and EN certification allow the same ballast to be used in North America and European markets. Metal Halide lamps can be dimmed down to 50% and SON lamps down to 35%. The degree of colour shift with Metal Halide lamps varies with lamp type but in the demonstrations I have seen this is not a problem.

We tested the Metrolight ballast with both the 22 Watt Philips Mini Master Colour and the GE 20W metal halide lamps, currently the lowest wattage Metal Halide lamps available. We measured a reduction of around 25% in light output without any noticeable colour shift in either lamp. The power reduction was around 18%. The larger wattage lamps and ballasts give greater dimming and energy saving effects.
Dimming down to these levels allows lighting scenes to be tuned by adjusting the light level of individual luminaires but it does not give the same range of adjustment as we are currently used to from fluorescent or incandescent dimmers. The primary advantage is energy reduction where the luminaires are dimmed as part of a daylight harvesting scheme or on a timed basis to save energy after businesses are closed.

Although dimming appears to be the most innovative feature the greatest energy saving capability of these ballasts is actually in the increase in lumen maintenance. By reducing lamp wall blackening Metrolight claim their ballasts help lamps to retain 90% to 95% of initial lumens to the end of life compared to 75% for magnetic ballasts allowing lower wattage lamps to be used to achieve lighting design levels.

Metrolight ballasts also apparently extend lamp life due to the microprocessor controlled, frequency-modulated operation. Lamp-life should be doubled compared to magnetic ballasts due to the higher frequency operation although dimming does slightly reduce this lamp-life enhancement.

Metrolight digital control allows up to 256 ballasts to be controlled remotely from a PC. The data link allows two way communication so that operating data can be monitored from each ballast.

We have used electronic ballasts in nearly all HID luminaire designs for the past five or six years to ensure optimum operation of the lamps. It seems as though Metrolight has now raised the bar for all suppliers of electronic ballasts. It will be interesting to see how far this technology can be developed in the future to enable HID lamps to be controlled to the same level as other light sources.

Metrolight UK can be found via


Save It Easy retrofit
The increasing pressure to reduce energy consumption in the lighting industry has resulted in a wide variety of innovations and bright ideas. The Save It Easy retrofit solution from ECS systems is one example of such an idea. It all seems quite obvious really – T5 lamps combined with electronic ballasts are much more energy efficient than T8 lamps working with magnetic ballasts but the cost of ripping out all those old T8 luminaires and replacing them with new T5 ones is jolly expensive.

So how about utilising the shorter T5 lamp length and developing a ‘magic’ quasi electronic ballast that fills up the space between the ends of the T5 lamp and the lampholders in the T8 luminaire and somehow works with the existing magnetic ballast? This means that you do not even need to open up the fixture to disconnect the old ballast.
Apart from the lamp the only other existing component you need to replace is the starter which is changed to a special fused link. By using the Save It Easy system you get all the benefits of T5 and electronic ballasts but none of the painful luminaire replacement costs.

With a payback of a year or two it would appear to be an ideal solution.
This is the basis of the Save It Easy system and it does work as a basic energy saving solution but it is a bit of a bodge and there are problems. As with so many energy saving lighting solutions, the emphasis is on the basic energy-saving but not on the lighting effect or quality of light.

The downsides of the system include its appearance that results in a rather ugly add-on device at the end of the lamp that gives a dark area. More importantly, the surface brightness of T5 lamps is much higher than T8 lamps so that glare issues are likely to result from retrofitting these lamps into unsuitable luminaires. The user should be wary that the increased surface brightness and resulting glare may contravene existing health and safety limits for office lighting equipment.

Unless the old luminaire is a simple switch-start magnetic type the Save It Easy system will not work without opening up the fixture and removing the old quick start ballast. Any emergency luminaires will not work with this system and of course the system will not work with a T8 luminaire already using an electronic ballast.

The other energy saving issues that seems to have completely passed by the makers of Save It Easy is the temperature sensitivity of T5 lamps. T5 lamps run at maximum efficiency above 35°C whereas T8 lamps are less temperature sensitive but also run at maximum efficiency at 25°C. By running a T5 lamp in a T8 luminaire the lamp is most unlikely to be run at the optimum working temperature and this could reduce the operating efficiency by up to 15% compared to one housed in a well-designed, dedicated T5 fixture.

In conclusion the Save It Easy system works but in a rather crude way and it is worrying to hear that many offices, schools and hospitals are considering using it on the basis of an energy review rather than seeking advice from a lighting consultant who will adopt a rather more holistic approach and consider the lighting effect as well as the energy savings.


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