Emergency lighting: What’s required, and how it’s designed

Understanding Emergency Lighting Requirements

Code officials place great emphasis on ensuring that emergency lighting is designed and installed in strict compliance with safety regulations. Any discrepancies or misinterpretations of these requirements can result in costly delays. To avoid these issues, it is crucial to have a clear understanding of the specific code requirements and the authorities' interpretation of ambiguous or conflicting regulations.

While the term "emergency lighting" is frequently mentioned in codes, it is not explicitly defined. For the purposes of this article, emergency lighting refers to lighting equipment specifically identified as such in the relevant codes, with a few exceptions. It is important to familiarize yourself with the codes applicable to your jurisdiction, including:

International Building Code (IBC), 2015 edition.
NFPA 70: National Electrical Code (NEC), 2017 edition.
NFPA 99: Health Care Facilities Code, 2015 edition.
NFPA 101: Life Safety Code, 2015 edition.
NFPA 110: Standard for Emergency and Standby Power Systems, 2016 edition.
NFPA 111: Standard on Stored Electrical Energy Emergency and Standby Power Systems, 2016 edition.

Different code-enforcement agencies may adopt various editions of these codes, so it is essential to verify the codes in force and consult with the authorities having jurisdiction (AHJ) for accurate interpretations.

Emergency Egress Lighting and Other Requirements

Emergency egress lighting is a fundamental aspect of emergency lighting and is addressed in both the IBC and NFPA 101. IBC Section 1008, which covers the means of egress illumination, mandates lighting for exit routes in most occupancies, with a few exceptions. The lighting must remain active whenever the building is occupied.

Under normal conditions, egress lighting is powered by the building's primary electrical supply. However, in the event of a power failure, an emergency power supply must illuminate specific areas, particularly the pathways to exits, the exits themselves, and exit discharges. The IBC provides several options for the form of the emergency power system, including onsite generators, battery-powered systems, or distributed batteries attached to individual luminaires.

NFPA 101 contains similar egress lighting requirements for all occupancies covered by the code, with a few exceptions. Compared to the IBC, NFPA 101 offers more specific guidelines for emergency lighting.

It is important to note that the IBC generally applies to new construction and renovation projects, whereas NFPA 101 is enforceable on both existing and new buildings. Designers should be aware of the separate requirements for existing and new facilities addressed by NFPA 101 for each occupancy type.

Key Locations for Emergency Lighting

NFPA 101 specifies that emergency egress lighting must be present in exit accesses, exits, and exit discharges. In the context of emergency lighting, "exit access" refers to designated stairs, corridors, ramps, escalators, and passageways leading to an exit. "Exit discharge" refers to similar designated building components leading to a public way. In most design projects, architects indicate these components in the life safety plans, but when such plans are not available, emergency lighting should be provided in corridors, stairways, exits, and areas immediately outside exits to ensure compliance.

The IBC also requires emergency lighting in spaces that are not used for egress, such as electrical rooms, fire command centers, fire pump rooms, and generator rooms. While the IBC is ambiguous about the specific performance characteristics required for these areas, it is advisable to provide adequate lighting on both the normal and emergency power systems to ensure safety.

Additionally, exit signs are essential along the egress path, at doorways leading to an egress path, and at exits. These signs must be placed to ensure visibility within a specified distance, typically no more than 100 feet or the listed viewing distance of the exit sign.

Performance Requirements for Emergency Lighting

Both the IBC and NFPA 101 outline general performance requirements for emergency egress illumination. These requirements ensure adequate lighting levels and duration during emergencies. The key provisions include:

Illumination levels of at least 1 foot-candle (fc) on average, with a minimum of 0.1 fc.
A maximum-to-minimum illumination level ratio of 40:1 or less.
Emergency lighting must remain illuminated for a minimum of 90 minutes.
At the end of the 90-minute period, illumination levels may decline to an average of 0.6 fc, with a minimum of 0.06 fc.

In addition, NFPA 101 requires that new emergency lighting power systems meet at least Type 10, Class 1.5, Level 1 requirements as defined in NFPA 110. This means that power restoration to emergency lighting should occur within 10 seconds after the normal power loss and last for a duration of 1.5 hours. These requirements ensure the reliability of the emergency power system, minimizing the risk of life-threatening situations.

It is worth noting that emergency illumination requirements for stairways can be subject to interpretation under NFPA 101. While detailed requirements for the illumination of egress paths exist, there are no specific requirements for stairways. Some authorities have enforced stricter rules regarding emergency lighting in stairways, which may require additional batteries or lighting units to meet the specified illumination levels.

Testing and Maintenance

Regular testing of emergency lighting systems is vital to ensure their proper functioning during emergencies. NFPA 101 mandates that lamps and power sources undergo periodic testing to verify compliance with code requirements. Monthly testing is required for all emergency lighting systems, regardless of the power source, and typically involves a short test of the battery and lamp.

For storage-battery and generator systems, testing involves de-energizing the normal power source serving emergency lighting and observing the illumination of the lamps. Generator systems must be tested monthly by initiation at a transfer switch and run under load for at least 30 minutes. Emergency lighting tests are typically performed in conjunction with monthly standby power system tests.

Storage-battery systems and unit equipment must undergo annual testing for a duration of 90 minutes. It is important to follow the manufacturer's recommendations for testing storage-battery systems, as the testing schedule may vary.

Electrical System Considerations

The installation requirements for power systems serving emergency loads, including emergency lighting, can be found in NEC Article 700, Emergency Systems. The IBC permits several power sources for emergency lighting, including storage-battery systems, onsite generators, and unit equipment. These power sources are also permitted under NEC Article 700, along with fuel cell systems and separate utility services, subject to compliance with specific regulations.

Key considerations for electrical systems serving emergency loads include:

Power restoration within 10 seconds of normal power failure.
Surge protection devices on emergency system switchboards and panelboards.
Strict separation of emergency system wiring from other wiring.
Adequate capacity to serve all loads connected to the system.
Selective coordination of overcurrent devices.
Fire protection for equipment serving emergency feeders.

Emergency Lighting in Health Care Facilities

Health care facilities have specific requirements for emergency systems, as outlined in NFPA 99 and NEC Article 517. Instead of defining an emergency electrical system, these documents define an essential electrical system, which includes a life safety branch, critical branch, and equipment branch. The life safety branch is responsible for emergency egress lighting, while the critical branch serves other lighting necessary for patient care and support.

The requirements for emergency systems in health care facilities differ from those in other occupancies. For instance, standby system capacity requirements are abrogated for health care facilities, allowing the system to be sized based on the maximum demand of the load. Additionally, selective coordination requirements are limited to faults lasting more than 0.1 second.

The applicability of fire-rating requirements for health care facilities can be subject to interpretation. While NFPA 99 exempts the life safety branch from compliance with fire-rating requirements, NEC Article 517 does not provide such an exemption. The AHJ should be consulted regarding the enforcement of fire-rating requirements during the design phase.

Hardware Options: Internally Illuminated Exit Signs and Unit Equipment

Both NFPA 101 and the IBC allow the use of internally illuminated exit signs, provided that they are listed for the purpose and approved by the AHJ. These signs utilize photoluminescence and radioluminescence technologies.

Photoluminescent exit signs absorb energy from incident light and release it slowly as visible light. They have a long usable life and require minimal maintenance, primarily consisting of cleaning the sign's face. However, their effectiveness can be affected by factors such as lighting control requirements and the compatibility with LED illumination.

Radioluminescent exit signs contain a small amount of radioactive material, typically tritium, which emits high-speed electrons that cause a phosphor to glow. While the tritium poses minimal health hazards, the signs require proper disposal and additional compliance measures.

Unit equipment, also known as battery-powered lighting, consists of rechargeable batteries, a battery charger, and provisions for connecting lamps. These units can be permanently installed or connected via flexible cord-and-plug connections of 3 feet or less. Unit equipment must be powered from the same lighting circuit that supplies normal lighting in the area.

Frequently Asked Questions

1. What is emergency lighting?

Emergency lighting refers to lighting equipment specifically identified in the codes for use during emergencies, such as power outages or fires. It is designed to provide illumination in key areas to enable safe evacuation and reduce panic during emergencies.

2. What are the requirements for emergency lighting?

The requirements for emergency lighting vary depending on the applicable codes and regulations. Generally, emergency lighting must provide adequate illumination levels for a minimum of 90 minutes. The lighting should be distributed along egress paths, exits, and other designated areas. Additionally, regular testing and maintenance are necessary to ensure the proper functioning of emergency lighting systems.

3. Can emergency lighting be powered by batteries?

Yes, emergency lighting can be powered by batteries. Battery-powered emergency lighting systems, such as storage-battery systems and unit equipment, are commonly used to provide illumination during power outages.

4. Are there specific requirements for emergency lighting in health care facilities?

Yes, health care facilities have specific requirements for emergency lighting outlined in NFPA 99 and NEC Article 517. These requirements differ from those in other occupancies and include provisions for essential electrical systems, emergency egress lighting, and critical lighting for patient care.

5. What are the options for exit signs in emergency lighting?

Internally illuminated exit signs, utilizing photoluminescence or radioluminescence technologies, are commonly used in emergency lighting. These signs eliminate the need for annual battery-duration testing and periodic battery replacement. However, they must be listed for the purpose and approved by the authorities having jurisdiction.

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