The LWF Blog
Fire Safety for Facilities Management Personnel – Emergency Escape Lighting – Part 168September 20, 2022 10:24 am
Lawrence Webster Forrest (LWF) is a specialist fire engineering and fire risk management consultancy whose aim is to give information on best practice in fire safety for facilities management personnel through this blog series. In part 167, LWF looked the types of emergency escape lighting system by considering Central Battery Systems. In part 168, we continue discussing Central Battery Emergency Escape Lighting Systems before considering Emergency Generators.
Central Battery Systems can be expensive to install and additional complexity and costs may arise from the need for sub-circuit monitoring. The nature of emergency escape lighting means that it is not illuminated at all times and because of this, monitoring relays in normal lighting sub-circuits will be required to ensure failures are detected and dealt with before the emergency escape lighting is required for use.
Despite the expense of installation, Central Battery Systems also have certain advantages over alternative emergency lighting systems. Where a system is required for a large installation with many luminaires, the use of vented cells means that a relatively long battery life of around 25 years is possible. The batteries themselves will require maintenance, but battery testing is simple and quick as there is only one battery installation. In a large building, central battery systems can therefore be cost effective over the lifespan of the system.
The use of an emergency generator to power emergency escape lighting is not generally a very practical solution for most applications. A generator may be useful to provide power for standby lighting, but there are some issues which make its use for emergency escape lighting impractical.
An emergency generator only starts up on total power failure. A fire is unlikely to affect all circuits, but much more likely to affect a limited number. Unless the generator supplies dedicated luminaires which are wired with fire-resisting cable, the solution is unlikely to be sufficient for emergency escape lighting.
The testing regime for generator systems requires that the system is tested monthly for an hour with at least two-thirds of the intended load connected. After testing, the generator must be refuelled ready for an emergency situation. Unless dedicated maintenance staff are employed and able to undertake these checks and safeguards, the commitment to an emergency generator system is likely to be too onerous for most organisations.
In part 169 of this series, LWF will look at the modes of operation of luminaires. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact LWF on freephone 0800 410 1130.
Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 25 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.
While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.