Why is Emergency Lighting Required
Emergency lighting is one of the most important safety systems in a building or plant area. Emergency lighting makes it possible for people to safely stop working and to evacuate, in case of an emergency. Emergency lighting is a vital and effective life safety tool, providing reassurance and guidance to people at critical times when they need to escape quickly and safely from a building or plant area in an industrial setting.
Effective emergency lighting is not only essential for ensuring the peace of mind of those responsible for the safe public infrastructure, commercial buildings and industrial plants – when six-figure fines and even prison are the price for getting things wrong. It's also a legal requirements in most countries enforced both by the authorities and insurers. Emergency lighting is heavily governed and defined by product, application and installation legislation standards covering occupational safety and building regulations.
Emergency Lighting is Supported by Laws and International Standards
Since emergency lighting safeguards life, it's requirement is clearly established by law, which in turn is supported by numerous British, European and International standards. These documents specify locations for emergency lighting, minimum lighting levels, installation and testing requirements, and product quality.
These regulations and standards impact on all parties involved in the provision of emergency lighting. From the manufacturer designing suitable products or the engineer preparing emergency lighting design, to the employer conducting risk assessments for life safety, all need to be aware of their respective obligations pertaining to emergency lighting.
IEC 60598-2-22 and EN 60598-2-22 specifies testing requirements for emergency luminaires for use with electrical lamps on emergency power supplies not exceeding 1000 V. This specific standard does not cover the effects of non-emergency voltage reductions on luminaires incorporating high pressure discharge lamps.
Emergency Lighting Systems
Emergency lighting is a standalone backup system, which does not rely on the functionality of the general electrical distribution system. It must always be operational and ready for use at anytme.
Specific requirements for emergency lighting are set out in law, and international standards. Emergency lighting can be implemented by two different ways:
- Centrally supplied emergency lighting system
- Centrally supplied means, that the back up power source is a central battery unit.
- Self-contained emergency and exit lights.
- Self-contained means, that the emergency lights contain their own backup power source, such as a battery.
Emergency lighting must be provided along escape routes, and in the open areas leading to them, to enable people to move quickly and safely to an exit.
- 50% of the illuminance must be available within 5 seconds and the full value within 60 seconds of supply failure in escape routes and open area.
- For high risk task areas the illuminance should generally be 10% of the normal mains illuminance or at least 15 Lux. This output must be fully achieved within 0.5 seconds
When determining the most suitable emergency lighting system, the possible restrictions imposed by the installation environment need to be taken into consideration.
Things to consider when you choose the emergency lighting system:
- Size of the building/site and the total number of emergency and exit lights
- Back up power source, and back up time requirements
- Technical performance level of the emergency lighting equipment
- Anti-panic illumination of open areas
- High risk lighting requirements
- Control procedures of the system (automatic/manual testing)
- Fire zones
- Environmental factors (recyclability, disposal of the parts and components, e.g. batteries)
Emergency Lighting with ON-OFF Switch or Photocell
For centrally supplied emergency lighting system, the wiring of the emergency lighting system is straight forward thus we will not cover it here.
Self-contained emergency lights are more complicated that even some electrical engineers do not understand how it operates. There are two basic requirements for a self-contained emergency light, a switched supply and an un-switched supply.
The switched circuit of the emergency light is where the on-off switch or a photocell should be connected while the un-switched circuit should be directly connected to the source and always have power regardless of the status of the on-off switch. In this scenario, the emergency light can be turned on or off.
In the event that there is an outage of the power source, the switched and un-switched circuit will have no supply. The emergency light will detect this event and the built-in battery pack of the emergency light will supply power to the unit.