Electrical Design Challenges in High-Rise Buildings

There are many unique challenges in the design and construction of high-rise buildings. The electrical design in these facilities is no exception, particularly regarding the emergency systems required to allow people to safely exit the building during a fire or emergency event.

A ‘high-rise building” is defined in the International Building Code (IBC) as “a building with an occupied floor located more than 75 feet above the lowest level of fire department vehicle access.” Code requirements in the IBC, National Electrical Code (NEC), and other standards include special provisions for these buildings to ensure occupant safety and maintain system integrity during rescue operations.  

IBC Chapter 4 describes specific requirements for high-rises, which include standby and emergency power requirements, as well as requirements for rooms housing indoor generators and protection for any associated fuel line piping.

Chapter 9 of the IBC outlines special requirements for fire alarm systems in high-rise buildings, which include special smoke detection requirements, wired firefighter phone locations, and voice alarm communications. Chapter 9 also outlines requirements for a dedicated fire command center to centrally locate and protect system annunciators, fire alarm components, elevator controls, and emergency communications systems.

In buildings where an accessible floor is four or more stories above the level of exit discharge, at least one accessible means of egress must include an elevator, which means the elevator must be supplied by the building emergency power system.  For buildings with “an occupied floor more than 120 feet above the lowest level of fire department vehicle access”, the IBC also requires two designated fire service access elevators.  These fire service elevators have additional requirements which include 2-hour protection ratings for elevator power and control cables and additional lighting requirements for the elevator hoistway, as defined in IBC Chapter 30.

General requirements for emergency two-way communications systems also apply here – stations are required at all areas of refuge locations and at all landings for elevators designated as a means of egress. Elevator landings serving floors above and below the level of exit discharge also must have two-way communication systems unless it is already provided at an area of refuge on the floor.

In addition to special IBC requirements, the NEC’s most significant “high-rise specific” section is found in NEC 700.10, which dictates that all feeder conductors for emergency wiring in a high-rise facility be fully protected by means of one of the following: automatic sprinkler protection, a dedicated fire-rated assembly, 2-inch concrete encasement, or listed circuit protective or thermal barrier systems.   

Close attention and appropriate application of these codes is necessary to ensure that your facility emergency systems remain operational if possible, during an emergency or fire event, giving first responders a chance to communicate with building occupants and those occupants a chance to safely exit the building. If you have any questions, please do not hesitate to contact Matthew A. Bergey, PE at (717) 845-7654 or mab@ba-inc.com.

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