Emergency Lighting Technology and Controls for Health Care Facilities

Design and installation strategies for egress lighting systems must work for the needs of each facility to determine the most optimal path.

Egress Lighting Insights

• Modern egress lighting balances safety and patient comfort with advanced dimming and control.
• UL 924 relays ensure egress lights provide full illumination during emergencies.

Between the strict code requirements and the ever-evolving controls, egress lighting systems become more difficult to design due to the complexities of modern control technologies.

For any health care facility, egress lighting is the most important element of its life safety system. Egress lighting is critical because it gets patients, visitors and staff to the proper egress areas, which are locations in the facility or exterior areas that are away from hazards and allow individuals to shelter in place.

In the past, egress lighting was relatively straightforward, typically achieved either through battery-powered fixtures or simple nightlights connected to a generator or uninterruptable power supply, operating continuously. These systems were used both for egress and security purposes. However, as building codes evolved, there was a growing emphasis on energy conservation, leading to LED lighting control technology advancements. These new control systems offered improved dimming capabilities and more flexible lighting adjustments, particularly beneficial in health care settings. Continuous bright lighting could disrupt the healing process, so the ability to adjust light levels allowed health care providers to create a more comfortable environment for patients. By tailoring the lighting to patient needs, advanced systems enhanced patient comfort and helped improve morale by making the facility feel less institutional.

Modern control systems offer multiple light-dimming methods and a variety of lighting styles, which can complicate maintaining proper egress levels. Ensuring adequate egress lighting requires the control system to activate the correct fixtures to achieve the necessary illumination for safe building evacuation. Engineers must navigate these complexities by integrating the control system with the generator or battery backup infrastructure to ensure that critical circuits in patient wings and major corridors are adequately powered. Relay technology can be employed to bypass the control systems, ensuring that egress lighting is maintained at the required levels regardless of the control system settings.

Integrating Emergency Lighting with Control Systems

One effective method for integrating emergency systems with control systems to ensure proper egress lighting is by using a UL 924 relay. This relay can be applied to individual fixtures or groups of fixtures, depending on the specific area and needs. It not only handles the emergency circuit but also maintains connections with the fixture’s normal power and control signals.

For instance, in a patient wing with perimeter patient rooms and a central nurses’ station, corridor fixtures are typically dimmed throughout the day to enhance patient comfort. While low light levels are beneficial for patients, they are insufficient for safe egress. In the event of a power outage, the generator would activate and engage the life safety transfer switch, distributing power to the patient wing via branch circuits. The emergency circuit would then power a range of fixtures in the corridor. These fixtures are normally connected to both the normal power circuit and the control system, which manages their dimming through a 0-10 voltage control signal.

The UL 924 relay, which integrates with the control system, plays a crucial role in this setup. It operates with three main components: the unswitched normal power circuit, the unswitched emergency power circuit and the 0-10 voltage control signal. During a power outage, the relay senses a loss of power in the unswitched normal circuit, disables the 0-10 voltage control and switches the power source to the emergency circuit, overriding the dimmed light levels and providing full egress illumination at 100% power from the life safety circuit.

Dedicated Emergency Lighting

Another effective approach is to use a dedicated emergency egress lighting system for specific areas. For example, in the patient wing scenario mentioned earlier, rather than integrating emergency egress lighting with the existing control system, implement a separate, dedicated egress lighting system that operates independently. In this setup, the dedicated emergency fixture is not illuminated under normal conditions. The primary control system manages normal lighting levels with non-emergency fixtures, while the dedicated emergency fixtures provide backup illumination during a power outage. When the generator activates, it supplies power to these emergency fixtures, which are designed to be both functional and aesthetically pleasing, blending seamlessly with the corridor’s architectural features. This approach ensures that adequate egress lighting is provided without the complexity of integrating it into the main control system. Although this method involves a higher initial cost, it simplifies the overall system and ensures reliable emergency lighting.

Ultimately, the choice between integrating egress lighting with existing control systems or using dedicated fixtures depends on the preferences of the designer or building operator. Some may prefer to keep egress lighting separate to avoid the added complexity of modern technologies and control systems. On the other hand, utilizing existing systems and saving the cost of dedicated fixtures can be advantageous from a startup perspective. This approach can be more cost-effective while still meeting egress lighting requirements.

Integral Battery Drivers

Another solution is to use integral battery drivers for LED lighting. This approach is less common in hospital settings, where leveraging existing generator systems is preferred. However, it is more suitable for outpatient facilities. In these environments, a battery backup can be integrated directly into each fixture or provided from a centralized source. If an outpatient facility lacks a generator or prefers to rely on battery backup for life safety needs, designers can opt for fixtures with either integral or remote battery backup capabilities. This allows for flexibility in maintaining emergency lighting, whether on a per-fixture basis or through a centralized system.

Power Distribution

Another key aspect is the distribution of life safety power, which varies based on the facility’s size. For large buildings like hospitals, generators must provide backup power for life safety systems, including egress lighting, along with other critical patient care functions. To comply with code requirements, transfer switch(es) will need to be installed to establish a life safety branch. The transfer switch needs to have the capability to start and transfer power to genset in less than 10 seconds.

Distributing power from the life safety transfer switch to branch panels must be isolated from the normal power and non-critical backup power to ensure reliability. When designing the distribution of egress lighting and deciding on branch panel locations, it’s crucial to consider the facility’s layout. The initial step is to identify specific areas, pods and floors, aiming for a distribution radius of approximately 277 feet around each life safety panel. This distance helps manage voltage drops effectively. The choice of voltage—whether 120V or 277V—will influence this radius. Egress lighting often operates at 277V, whereas other life safety systems typically use 120V. For 120V systems, a 120 foot radius is recommended for the life safety panel. While matching the radius to the voltage is a good rule of thumb, detailed calculations are needed to ensure that voltage drop and other factors are properly addressed.

With the critical nature of the role egress lighting plays, it is important to have a comprehensive understanding of the different approaches to achieving it. There are pros and cons to each, and each setting should be thoroughly studied to guide the best strategy. Egress lighting is part of the life-saving system and should be treated as such.