EMERGENCY LIGHTING

Emergency lighting is a self-explanatory feature that activates during power failures, ensuring illumination in emergency situations such as fires or power outages when regular lighting systems fail. Without this backup, sudden darkness poses risks to occupants, potentially leading to physical harm or panic.
It's designed to function automatically, providing adequate illumination for safe evacuation regardless of age. In modern constructions, emergency lighting is typically integrated during the building phase, with specifications outlined by local authorities, architects, or consultants.
The IS 3217 Standard acts as a guide for emergency lighting designers, outlining fundamental principles. It encompasses various premises like residential buildings, hospitals, schools, offices, and more. While it suggests specific types and durations of emergency lighting for each premise category, it's essential to note that these are minimum safety standards, and certain installations might require higher standards for optimal safety.

Type of Systems

Most emergency lighting schemes fall into one of the following categories:

  • Non-maintained - The emergency light units only illuminate in the event of a mains failure.

  • Maintained - The emergency light units are illuminated at all times using the same lamps for both normal and emergency operation.

  • Sustained - The emergency light units are fitted with two lamps or two sets of lamps. One of which operates on mains 240V AC supply, the other which operates from the battery supply in the event of mains failure. It is basically a non-maintained system with the addition of mains lamps which should be illuminated whenever the premises are occupied.

The type of system and emergency duration is often expressed in abbreviated form as per the following examples:

  • M3 - Maintained System, emergency duration 3 hours.

  • NM2 - Non-maintained System, emergency duration 3 hours.

  • S1 - Sustained System, emergency duration 3 hours

Siting of luminaire's/signs

After establishing the fundamental system, it's important to determine the placement of lighting units and signs within the specific premises. This positioning will guide your equipment selection.
Lighting units and signs should be positioned to clearly display exit routes towards the final exits from the premises. When these routes or exits aren't immediately obvious, signs should be used rather than lighting units. Attention to detail is crucial, especially for stairways, level changes, corridor intersections, directional shifts, exterior final exits, control/plant rooms, lifts, and larger toilet areas (although some advocate for emergency lighting in all public and especially disabled-accessible toilets). Fire alarm call points and firefighting equipment should have clear illumination.
Using common sense to position luminaires and signs effectively across these areas generally ensures that the completed scheme meets most requirements. Note: Detailed computer-based calculations or spacing tables from luminaire manufacturers should guide the process.

Areas to be covered

There is legislation, guides, British and European standards that require emergency lighting to be installed and the area it should cover. An emergency escape lighting system should normally cover the following areas,

  • each exit door

  • escape routes

  • intersections of corridors

  • outside each final exit and on external escape routes

  • emergency escape signs

  • stairways so that each flight receives adequate light

  • changes in floor level

  • windowless rooms and toilet accommodation exceeding 8m2

  • firefighting equipment

  • fire alarm call points

  • equipment that would need to be shut down in an emergency

  • lifts and areas in premises greater than 60m2

It is not necessary to provide individual lights (luminaire) for each item above, but there should be a sufficient overall level of light to allow them to be visible and usable.