What is in this article?:
- The Latest Trends in Emergency Lighting
- SIDEBAR: Considering ALCRs in Your Design
Designing emergency lighting systems for efficient and safe operations
Emergency preparedness is an aspect of building operations that is often overlooked until an imminent situation is looming. In the aftermath of Hurricane Sandy in the Northeast and similar natural/physical security concerns across the United States, newfound attention will inevitably be placed upon preparing for the unexpected. Now is the time to revisit updates for emergency lighting needed to ensure safety in your facilities.
However, recent advances in technology have created confusion in some cases related to installation and maintenance best practices. With a variety of new products entering the market that use different wiring techniques and operation means, how do facility personnel understand how their egress lighting system should operate to meet NEC compliance? This article provides an explanation of several sections of Art. 700 in the 2011 NEC and offers tips on developing a cost-effective and efficient emergency lighting control strategy.
2011 NEC requirements
Various wiring methods, the lack of common layout practices, and confusion on how devices should operate have complicated testing requirements and caused increasing numbers of delays in electrical inspections nationwide. Created in response to this confusion and rising demand for UL compliance and energy-efficient operations, Art. 700 outlines the safe electrical operation of emergency lighting and control systems — and describes how a facility should operate when normal electrical supply is interrupted.
While numerous changes have been adopted, three significant amendments deserve extra attention to ensure proper usage:
1. Definition of automatic load control relay (700.2): “A device used to energize switched or normally off lighting equipment from an emergency supply in the event of loss of the normal supply and to de-energize or return the equipment to normal status when the normal supply is restored.”
This section provides an introduction to and market definition of automatic load control relays (ALCRs), also known as shunt relays or emergency relays. See SIDEBAR: Considering ALCRs in Your Design.
2. Description of branch circuits for emergency lighting (700.17): “Branch circuits that supply emergency lighting shall be installed to provide service from a source complying with 700.12 when the normal supply for lighting is interrupted. Such installations shall provide either of the following:
a. An emergency lighting supply, independent of the normal lighting supply, with provisions for automatically transferring the emergency lights upon the event of failure of the normal lighting branch circuit.
b. Two or more branch circuits supplied from separate and complete systems with independent power sources. One of the two power sources and systems shall be part of the emergency system, and the other shall be permitted to be part of the normal power source and system. Each system shall provide sufficient power for emergency lighting purposes. Unless both systems are used for regular lighting purposes and are both kept lighted, means shall be provided for automatically energizing either system upon failure of the other. Either or both systems shall be permitted to be a part of the general lighting of the protected occupancy if circuits supplying lights for emergency illumination are installed in accordance with other sections of this article.”
This section provides an explanation of how power is fed to the ALCR through two different panelboards. Depending on user need, ALCRs can be stand-alone devices or integrated directly into the electrical panel. The Figure illustrates a typical stand-alone ALCR arrangement.
3. Explanation of use of ALCR (700.24): “If an emergency lighting load is automatically energized upon loss of the normal supply, a listed automatic load control relay shall be permitted to energize the load. The load control relay shall not be used as transfer equipment.”
This section defines and limits how an ALCR works.
Considering these three parts of the 2011 NEC, electricians are facing new design challenges when it comes to wiring and operation. With the variety of egress lighting products currently on the market, electricians must now understand how to organize cabinet wiring for each individual product — creating an obstacle that had never before existed.
When determining the appropriate emergency lighting control strategy for their needs, facility personnel should consider a number of factors related to costs, codes, standards, and equipment.
Assessment plan — As an initial step, facility personnel should determine their operational and financial goals. This means not only establishing a feasible budget for a potential upgrade or retrofit, but also understanding the project’s potential return on investment and total cost of ownership — from initial equipment purchase to installation to everyday upkeep.
Sustainability and efficiency objectives should also be considered. Sustainable or energy-efficient solutions will help facilities meet desired “green” standards as well as reduce overall costs. Additionally, many local, state, and federal governments provide assistance, grants, and tax breaks for facilities that meet certain sustainability criteria.
A third factor to consider is Code compliance. All equipment and installation procedures should be designed and installed according to adopted NEC standards. Facility personnel should also evaluate how state and local regulations will affect the specific goals laid out in step one.
Implementing and maintaining technology — Commercial buildings using the 2011 Code have more options and flexible design considerations to factor in to greatly reduce maintenance time and help streamline operations.
• Fixture-level ALCRs, while a less costly alternative to battery-backed egress lighting, still require time-intensive testing requirements, as each relay must be tested at the individual device level.
• Emergency lighting panels are centralized, self-contained solutions designed to be mounted between emergency and regular circuit breaker
panelboards. With ALCRs integrated directly into the panel, devices are no longer scattered throughout the facility, with testing and maintenance able to be completed at a single location.
• Similar to the stand-alone panel, emergency lighting panelboards speed installation and inspection by requiring less wiring.
The first priority for emergency lighting is to ensure safety. With advances in codes and standards, cost savings and streamlined operations can easily be integrated into an emergency lighting strategy, allowing for easier installation and maintenance by facility personnel. With many manufacturers now designing products that are installed, operated, and maintained differently, new obstacles for electricians and inspectors have been created. By understanding changes to the 2011 NEC, learning more about available technology, and following simple planning steps, you can ensure efficient and safe operations of your emergency lighting system.
Eidson is a certified energy manager for the North American LifeSpace business of Schneider Electric in LaVergne, Tenn. Eidson can be contacted at Kelly.Eidson@Schneider-Electric.com.