How long should emergency lighting stay on during a power outage?

Emergency lighting plays a vital role in ensuring the safety of occupants during unexpected power failures, enabling safe and orderly evacuation. In the UK, the duration for which emergency lighting should remain operational is governed by both legal and practical considerations, primarily outlined in BS 5266-1:2016 and enforced through the Regulatory Reform (Fire Safety) Order 2005.

According to these standards, emergency lighting must remain illuminated for a minimum of one hour following the failure of normal mains power. However, the most commonly recommended and implemented duration is three hours. This extended duration allows time for the safe evacuation of a building, potential re-entry by emergency services, and for the power supply to be restored or alternate arrangements to be made.

The choice between one hour and three hours typically depends on the type of premises. For example:

• Residential and small commercial premises may only require one-hour duration if re-occupation is not expected until mains power is restored.
• Larger commercial, public, and industrial buildings, as well as places of assembly like theatres and shopping centres, should have three-hour emergency lighting. This ensures that building staff and emergency responders have sufficient time to manage evacuation, conduct checks, and resolve any ongoing incidents.

In the case of emergency escape lighting, such as those installed along stairwells, corridors, and exit points, it’s essential that the lighting remains bright enough (typically around 1 lux) to clearly illuminate the escape path for the entire duration. For high-risk task area lighting, higher lux levels are required to enable the safe shutdown of equipment.

It’s also important to note that emergency lighting systems must be self-contained or centrally powered, and must undergo regular testing. Monthly functional tests ensure lights switch on correctly, while annual duration tests confirm they operate for their full rated duration.

In summary, the standard recommendation is three hours of emergency lighting, offering maximum safety and flexibility. This duration ensures that, during a power outage, occupants can exit safely, and emergency teams can work efficiently, even in the most demanding environments. A well-designed, compliant emergency lighting system is not only a legal obligation but a critical element of a building's overall safety strategy.

What is the difference between maintained and non-maintained emergency lighting?

Emergency lighting is an essential safety feature in commercial, industrial, and public buildings, ensuring visibility and guidance during power failures. There are two primary types of emergency lighting systems: maintained and non-maintained. Understanding the difference between them is crucial for ensuring compliance with UK safety regulations and choosing the right solution for your premises.

Maintained Emergency Lighting

Maintained emergency lighting is designed to operate both during normal mains power and in the event of a power failure. These lights remain on at all times, making them suitable for areas where consistent lighting is necessary, such as public access areas, cinemas, theatres, and commercial spaces where lights must be illuminated even when the main lighting system is active. In the event of a power cut, these fittings automatically switch to battery power, continuing to operate without interruption.

This type of lighting is particularly important in environments where people are unfamiliar with the building layout, as it provides constant reassurance and visibility. Maintained emergency lights often double as both general and emergency lighting, making them a versatile and practical choice for many facilities.

Non-Maintained Emergency Lighting

Non-maintained emergency lighting, on the other hand, remains off during normal operation and is only activated in the event of a mains power failure. These lights are typically powered by an internal battery that charges when mains electricity is available. Upon power loss, the lighting activates automatically to provide illumination for a minimum of one to three hours, depending on the system's design and legal requirements.

Non-maintained lights are more commonly used in workplaces, storage facilities, stairwells, and utility areas where normal lighting is always present, and emergency lighting is only needed during an actual outage. They are also preferred where energy efficiency is a consideration, as they are not consuming power continuously.

Choosing the Right Type

The selection between maintained and non-maintained emergency lighting should be based on the building's use, the expected occupancy, and the applicable safety standards. In many cases, a combination of both types is used throughout a single premises to provide comprehensive coverage.

Both maintained and non-maintained emergency lights must comply with BS 5266-1 standards and be regularly tested and maintained to ensure proper function during emergencies. Choosing the correct type not only supports legal compliance but ensures a safe environment for all occupants during critical situations.