Elevating Emergency Power Requirements for Elevators

There are many items in the International Building Code that are different from the Uniform Building Code and can affect the electrical distribution system in commercial buildings.

By Keith Lane, P.E., RCDD/NTS Specialist, LC, LEED AP, Vice President, Engineering, SASCO, Seattle March 8, 2005

The IBC (International Building Code) is coming. In the State of Washington, all projects that obtain a building permit after July 1, 2004 will have to follow the International Building Code. Prior to July 1, 2004, all projects followed the UBC (Uniform Building Code).

There are many items in the International Building Code that are different from the Uniform Building Code and can affect the electrical distribution system in commercial buildings. This article will focus on three of these issues, buildings with four or more stories, exterior egress lighting to the public right of way and air conditioning load in the elevator room now required to be on the standby generator set.

The International Building Code requires buildings that are four or more stories to have the elevator to be part of the standby power system. Potentially, many new projects would now be required to implement a standby generator into the electrical distribution system.

IBC 2003 Section 1007.2.1 Buildings with four or more stories : indicates that, “In buildings where a required accessible floor is four or more stories above or below a level of exit discharge , at least one required accessible means of egress shall be an elevator complying with Section 1007.4.”

IBC 2003 Section 1007.4 Elevators : indicates, “An elevator to be considered part of an accessible means of egress shall comply with the emergency operation and signaling device requirements of Section 2.27 of ASME A17.1 Standby power shall be provided in accordance with section 2702 and 3003. The elevator shall be accessed from either an area of refuge complying with Section 1007.6 or a horizontal exit.”

IBC 2003 Section 2702.1 Where required : indicates, “Emergency and standby power systems shall be installed in accordance with the ICC Electrical Code*, NFPA 110 and NFPA 111.”

*The International Electrical Code has not been adopted in our area; in this case we have completed building installations in accordance with the 2002 National Electrical Code. In July of this year, the 2005 National Electrical Code will be enforced.

IBC 2003 Section 2702.2 Where required : indicates, “Emergency and standby power systems shall be provided where required by Sections 2702.2.1 through 2702.2.19.”

IBC 2003 Section 2702.2.5 Accessible means of egress elevators : indicates, “Standby power shall be provided for elevators that are part of an accessible means of egress in accordance with Section 1007.4”

IBC 2003 Section 3003.1 Standby Power: Indicates, “In buildings and structures where standby power is required or furnished to operate an elevator, the operation shall be in accordance with Section 3003.1.1 through 3003.1.4.”

These referenced requirements in Section 3003.1 refer to the transfer of all the elevators in the bank and details the requirements for the automatic transfer to standby power within 60 seconds after failure of normal power. In addition, this section allows for the standby generator to be sized for only one elevator in a multi elevator operation when the elevators can be sequenced to operate only one elevator at a time under generator power and require any machine room venting or air conditioning to be connected to the standby power source.

This requirement first came out in the 2000 edition of the International Building Code. At this time, there was some confusion about what constituted a four story building. The International Building Code came out with an Interpretation number 27-03 issued on 03/08/04 to clarify this issue. This interpretation indicates, “A “level” is a horizontal plane that is part of a story, not the entire story height. A story is the vertical space between the upper surface of one floor level and the upper surface of the floor level next above or below.” This interpretation essentially indicates that the first story of the building is indeed the first story above the level of exit discharge. Before this interpretation, one could potentially conclude that this 2003 IBC code would only apply to five story buildings, four stories above the level of egress, the first floor.

The electrical engineer or electrical distribution system designer should coordinate with the Authority Having Jurisdiction (AHJ) to verify what their specific interpretations and requirements are on this IBC Code issue.Based on the 2002 NEC Section 701.11(E), if the Authority Having Jurisdiction approves, a connection ahead of service disconnecting means can be utilized as the legally required standby power source in lieu of a standby generator for an elevator. In addition, there are some exemptions noted in Section 1007.2.1. As with the basic code interpretation, all exemptions should be pre approved by the AHJ prior to completion of the electrical distribution system design.

Another significant portion of the International Building Code that differs from the Uniform Building Code and impacts the electrical distribution system is section 1006, “Means of Egress Illumination”. More specifically, 1006.3 Illumination emergency power; “The power supply for means of egress illumination shall normally be provided by the premise’s electrical supply. In the event of power supply failure, an emergency electrical system shall automatically illuminate the following areas”:

(5): The portion of the exterior exit discharge immediately adjacent to the exit discharge doorway in buildings required to have two or more exists. *

* (1) through (4) are not covered in the scope of this article.

* Exit Discharge: The portion of the means of egress system between the termination of the exit and a public way.

The 2003 edition of the Life Safety Code, Section 3.3.175 defines a public right of way as “A street, alley or other similar parcel of land essentially open to the outside air, deeded, dedicated, or otherwise permanently appropriated to the public for public use and having a clear width and height of not less than 30 feet and 6 feet.”

This section noted above illustrates the requirement for emergency lighting from an exit discharge to the public right of way. The typical wall mounted egress light over an exit doorway will now have to provide emergency illumination to the public right of way, which could be a significant distance away from the building. The typical wall mounted egress light is provided with a metal halide light source. In this situation, if a generator is installed with the building an arc maintenance device would be required to ensure proper light levels within the 10 seconds as prescribed by Section 700 of the National Electrical Code. If there is no emergency standby generator in the electrical distribution system, a fluorescent light fixture with an integral battery or a metal halide light fixture fed from a “fast transfer” centralized lighting inverter would be required. In either case, per Section 700 of the National Electrical Code, 90 minutes of backup would be mandatory. Another issue with this section of the International Building Code is that the public right of way could potentially be quite some distance away from the building. If this is the case, additional light fixtures on the exterior of the building and/or along walkways with emergency lighting provisions may be required to obtain the minimum average foot candles and uniformity ratios from the building to the public right of way.

3) Air conditioning load in the elevator room is required to be on the generator set
IBC Section 3003.1.4 Venting: Indicates, “Where standby power is connected to elevators, the machine room ventilation or air conditioning shall be connected to the standby power source.”

These HVAC loads must be coordinated with the building team mechanical engineer. The electrical engineer must ensure that the emergency standby generator has enough capacity to feed this additional air conditioning load.

It is important to understand the International Building Code change with respect to the Uniform Building code. Especially as it relates to the electrical distribution system. These changes can be expensive and must be implemented from the very beginning of the design phase. Not understanding these International Building Code requirements will only create more pain and expense during the plan review and construction phase of the project.