Ok, so emergency lighting, it’s a topic that is well documented and has standards and guidance documents that provide information on design, installation and testing.

It is a legal requirement and should form part of the Risk assessment of any building.

Therefore, one would assume that the market has this covered and everything should be rosy within the world of emergency lighting.

Well, for the most part the better companies do have this covered and designers be they independent or associated with an OEM are competent and deliver schemes that fully comply with best practice and all relevant standards.

Now for every good company there are those that look to value engineer emergency lighting and take cost out to reduce performance and often safety. To be fair to them they are just comparing one product with another and assuming they are comparable, however this is very often not the case.

If something is significantly cheaper then there is a reason and more often than not this is down to a compromise in the quality of the components or the build of the luminaire.

We can therefore split an emergency luminaire into four constituent parts.

The invertor, the battery, the optics and its construction, let’s look at these individually.


The Invertor or driver is key to how the emergency luminaire will function as well as its operating life. A quality invertor contains between 100 to 150 components the careful selection of these components along with their positioning and operating parameters determines the life of an invertor. Reducing the thermal characteristic of a capacitor for example can save cost but in the long run will reduce operating life significantly.

Not all components are created equal, and poor selection or inadequate testing can result in premature failure after all it only takes one component to fail and you have a useless piece of plastic and electronics. Product standards such as BS EN 60598 2-22 set the bench mark for safety but don’t always consider the performance aspects of the device, also we mustn’t forget the implications of interference from poorly protected circuits in the growing trend towards wireless communications. A noisy signal could play havoc with your controls. If in doubt, ask for test data and carefully look at the performance of the invertor as a minimum ask for accredited test data.


The battery; this is equally as important as the invertor as they should be a matched pair, one designed to fully optimise the other. Different battery technologies have different charging regimes and each chemistry has characteristics that should be managed appropriately.  Also, be aware that individual cells in battery sticks can be rated according to any number of variables and when comparing batteries one white stick battery looks very much like another.

The trend towards Lithium solutions is a positive step with many benefits and is a proven technology used in all of our smart tech, but again there are a number of different Lithium solutions and its critical you select the correct Lithium solution for emergency lighting. Typically, this is Lithium Ion Phosphate LiFePO 4. Again, cells and management of Lithium does vary so ensure the cells are managed correctly. Also, it’s worth pointing out that technologies such as NiCd and NiMH both suffer from their own challenges with NiMH limited by the number of full switching cycles and as a consequence multiple power cycles of connected NiMH batteries during the construction phase can dramatically reduce their life.

You should never replace batteries without confirming compatibility with the original manufacturer and I would recommend playing it safe and always use an original manufacturers battery.


Optics and I am going to include the light source within this section as well.

LED’s have revolutionised emergency lighting and for the most part they provide a decent output and if they are non-maintained will continue to function for the design life of the emergency luminaire.

Optics on the other hand are an interesting topic and one that does consider some investigation. Typically, we have two standard lens options, Open area and Corridor lens. The Open Area gives a 360-degree distribution and is used to provide a pool of light that gives general illumination in an open space. The Corridor lens is a shaped optic that is designed to throw light in an elliptical pattern to illuminate a narrow space whilst providing the maximum spacing between luminaire. It is critical that these are orientated in the right direction otherwise you have a beautifully illuminated wall!

Specialist lens are manufactured for applications such as High bay emergency lighting or for high risk areas and again they provide a unique distribution of light in emergency mode that are task specific.


Construction is a major challenge as one white plastic looks very much like another but its critical the material used is suitable for the task and this includes the body and often the lens or diffuser. All emergency luminaries must pass the 8500C glow wire test and the selection of plastic is critical. Metal luminaires have their own challenges and again plastics will generally feature heavily; think of an emergency exit luminaire for example.


If a product is cheap then there is a very good reason why it is so and often this is due to a compromise in one of the afore mentioned elements of an emergency luminaire.

Remember above all else this is a life safety critical product and whether you import or manufacture you have a responsibility to provide a compliant product. As a manufacturer or importer, you have a legal requirement to hold a technical file for any emergency luminaries you sell into the market.

Organizations such as LIA/ICEL and CIBSE SLL provide guidance on emergency lighting but if in doubt ask for proof of compliance. If you are forced to value engineer a project, then consider long and hard before you compromise the integrity of this Life safety system

If you want to discuss you’re emergency lighting requirements in more detail as well as the testing and monitoring, then don’t hesitate to give me a call or drop me a line.