One of the problems close to the heart of the Industry Committee on Emergency Lighting (ICEL), and to many designers, is the quality of the conversion. As Grant Daniels of Zumtobel Staff Lighting warns: "There are many attributes of emergency lighting that need to be looked at, and the process of conversion is a lot more complex than many of the converters realise."
One thing that specifiers need to be particularly aware of is that as soon as a standard luminaire is modified in any way its CE mark is invalidated until all of the relevant tests have been carried out again. Yet, it would appear, this is rarely the case and many specifiers are effectively allowing illegal products to be installed on their projects.
"The majority of conversion houses do not do anything to fulfil the CE requirements," says David Wright, chairman of ICEL and managing director of Existalite. "When the luminaire comes in from the manufacturer it has been tested in compliance with the Construction Products Directive, the Low Voltage Directive and the EMC (electromagnetic compatibility) Directive. The conversion house will change the wiring, move components and introduce new components so if they do not carry out tests on thermal and electrical safety and electromagnetic compatibility they cannot be sure it complies with the standards," he continues.
In order to provide a standard and accredited procedure for conversions, ICEL introduced a guide called ICEL 1004 and those companies accredited to ICEL 1004 are committed to carrying out all the appropriate tests. Yet there are dozens of conversion houses operating in the UK and only a handful are accredited to ICEL 1004.
Of course, the fact that these conversion houses have not gone through the accreditation procedures doesn't necessarily mean they are not carrying out the testing – though some of the competitive pricing makes it difficult to imagine they have. "Companies doing it properly cannot do it as quickly or cheaply as the conversion sheds because we have to invest in the testing equipment and the technicians to use it," David Wright explains.
"For example, we recently had a complaint from a customer about the time required to convert some luminaires, saying that they knew of a conversion house that could provide next day delivery. But the thermal endurance test alone takes 24 hours, so they could not have been doing the testing required for the CE mark," he continues.
But is this a case of bureaucracy against common sense or are there real concerns for the specifier? Given the interaction of the various components of a luminaire, the effects of a bad conversion can be significant. "There have been a number of instances where batteries get too hot and the cables are not safe," Wright points out. "And you only need to increase the length of the cables to a high frequency ballast by 50 mm to make the difference between a pass and a fail for electromagnetic compatibility".
In an ideal world, therefore, the manufacturers of the standard luminaires would also carry out the conversions, but they do not always offer what the designer needs. "Our preferred option is always to get the manufacturer to do it but we have had more success with the smaller companies than with the larger manufacturers," recalls Simon Dicks of FaberMaunsell. "They are generally more flexible in meeting space and other design parameters and will often source gear that's small enough to fit in the space available in the ceiling. The manufacturers, on the other hand, tend to have only one size of box," he adds.
The problem becomes more pronounced as luminaires become smaller and there is less space to fit everything in. "As fittings become more compact, such as T5 luminaires, there is less space for the components, yet the emergency inverters and batteries have remained at about the same size", Grant Daniels points out. "This often means that conversion requires more than just shoehorning in the emergency components, it may be necessary to rearrange the other components of the fitting."
Not only does this strengthen the argument for re-testing the converted luminaire, it also raises concerns about what happens when there isn't space to rearrange the components. For example, if a ballast that runs at 120°C is placed next to a battery rated for 50°C, simply because it fits there neatly, the battery life will be reduced.
"There is a 'getting away with it' attitude that prevails but these are life safety products and having a battery fail after 12-15 months is just not acceptable," Wright adds.
Problems with mercury
Adding to the general challenge of squeezing all the bits in to the space available, today's lower mercury content fluorescent lamps make greater demands on the battery – requiring one or two extra cells but not always getting them.
"Many conversions use the same size of battery for a low mercury lamp as they do for the older style of lamp, whereas what would have once been fine with a three-cell battery may now need a five-cell battery," notes Bob Venning of Arup Lighting. "The problem is that this makes the pack bigger and more expensive so the converters shy away from this. Nor is this just a problem with new T5 and other high frequency lamps, there can also be problems with retrofitting T8 lamps. It's another reason for using an ICEL accredited converter," he adds.
The problem has arisen because lamp manufacturers have progressively reduced the amount of mercury in their fluorescent lamps – for both environmental and cost reasons. In fact, modern fluorescent lamps use less than 10% of the mercury they contained 20 years ago.
They work fine with an ac supply but problems can arise when they are operated from a dc supply or on ac supply with a dc bias. In emergency mode, they need more energy applied to the cathode to strike the lamp, and this necessitates the use of a larger battery.
If the emergency pack has been designed with low mercury lamps in mind, there's no problem but when a low mercury lamp is retrofitted to an existing fitting it can all go pear-shaped. "When these lamps are used as replacements, then very often something that has been working fine either doesn't work at all because the lamp won't start, or the light output will fall or you will get end-blackening," notes David Wright.
It's not that the problem is insurmountable, far from it, but there does seem to have been a breakdown in communications. In particular, according to Wright, the lamp manufacturers are far from forthcoming. "When a lamp changes the standards dictate how we deal with that technically so there should be no problem. However, the lamp manufacturers change the lamps with no recourse to the rest of the industry, because they say they don't want to pre-warn the competition.
"Luminaire manufacturers take responsibility for modifying the designs when the lamps change but we can only do that if the lamp manufacturers tell us they've done it! For example, when mercury levels were reduced in the 28W 2D lamp the three-cell 3·6 V battery that had been suitable for emergency packs had to be increased to a four-cell 4·8 V battery. However, because cost has become all important, the industry is driven to use as few cells in the battery pack as possible.
Which brings us back to the old problem of cost and which comes first, the price or the integrity of the design. Specifiers are being put into increasingly difficult situations in all areas of building services but when it comes to life safety the word cost has more than one meaning. Emergency lighting is certainly an area that requires careful deliberation.
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Building Sustainable Design
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