Imagine a bustling office building plunged into darkness. The power outage initially creates chaos and confusion, but the emergency lighting system quickly steps in to calm the situation. It’s the unsung hero, guiding people safely to exits during emergencies.
Understanding the basics
Before diving into the technicalities, let’s clarify two key terms:
- Egress lighting: This refers to the continuous illumination of escape paths during normal building operations.
- Emergency lighting: This system kicks in during power outages, providing additional illumination to complement egress lighting and illuminate exit signs. Some luminaires can serve both purposes, while others are dedicated to emergency use.
The regulatory landscape
Designing and implementing emergency lighting systems is complex due to various safety regulations and codes. Key codes governing emergency lighting include:
- NFPA 101 (Life Safety Code): Sets standards for occupant safety in buildings.
- International Building Code (IBC): Outlines requirements for means of egress.
- NFPA 70 (National Electrical Code - NEC): Governs the safe installation of electrical wiring and equipment.
- Underwriters Laboratories (UL) safety standards: Define the performance standards for emergency lighting products.
Balancing normal and emergency operations
NFPA codes differentiate between normal building operations and emergencies. During normal operations, a minimum of 1 foot-candle (fc) of illumination is required along escape paths. However, during emergencies, the requirements are stricter:
- Rapid activation: Emergency lighting must activate within 10 seconds of power loss.
- Duration: It must remain illuminated for at least 90 minutes.
- Illumination level: A minimum average of 1 fc is required with a minimum of 0.1 fc.
Controlling the lights: A delicate balance
To ensure optimal performance, continuous egress lighting can be provided by general luminaires strategically placed along escape paths. However, NFPA 101 allows for turning off these luminaires under certain conditions, including:
- Listed control devices: The control device must be UL-listed.
- Automatic emergency power activation: The system must automatically switch to emergency power upon power loss.
- Illumination timers: Timers should have a minimum 15-minute delay.
- Occupancy sensor activation: The system should activate based on occupant movement.
- Fire alarm integration: The system can be integrated with the building’s fire alarm system.
- Exclusions: The control system should not affect photoluminescent exit signs, battery-equipped emergency luminaires, or other critical lighting elements.
Navigating energy codes
Commercial building energy codes often require automatic shutoff for lighting when not in use. However, exceptions exist for emergency and egress lighting. For instance, the International Energy Conservation Code (IECC) and California’s Title 24 allow specific lighting loads to remain on for egress purposes.
Choosing the right lighting solution
When selecting emergency lighting solutions, consider the following options:
- Building power generator and inverters — Including single-phase mini-inverter systems designed to provide emergency power for lighting applications.
- General luminaires with EM drivers/ballasts — With a battery pack, luminaires can serve normal and emergency lighting functions, eliminating the need for separate emergency power sources.
- General luminaires with connected lighting and EM capabilities — Recently wired and wireless control systems provide reliable emergency lighting control without additional wiring or emergency transfer devices.
The future of emergency lighting
With advancements in LED technology and control systems, emergency lighting is becoming more integrated with overall building automation systems. This integration offers greater flexibility, efficiency, and enhanced safety. By understanding the complexities of emergency lighting and adhering to relevant codes and standards, building owners and designers can ensure the safety of occupants during power outages and other emergencies.
