Building code standards for seismic certification require that critical electrical equipment, such as automatic transfer switches, transformers, motor control centers, and other on-site power gear, must endure expected ground acceleration levels or risk being red tagged during inspection — or worse. Who assigns these ground acceleration levels? The U.S. Geological Survey does. More broadly applied today than in the past, these International Building Code (IBC) standards could have important consequences for electrical contractors who buy, install, test, and maintain on-site power equipment. A basic understanding of seismic design requirements and your responsibility/potential liability as a project team member is critical for you to protect your business interests.
IBC 2009 and CBC 2010 refer to ASCE 7-05 as the performance benchmarks for seismic criteria. An important element in designing power systems to resist seismic events is seismic demand spectrum. SDS represents the base acceleration forces for a specific site, which can range from 0 to 2.48. Equipment must be certified to the SDS values for both the site at which it will be installed and the location in the building where it will operate. For example, power systems installed on rooftops in California must be certified for rooftop applications at the SDS value for the project. A typical value might be 1.93.
With the well-populated West Coast particularly vulnerable to seismic events, California’s Office of Statewide Health Planning and Development (OSHPD) has taken the lead and essentially become the de facto national approval agency with its pre-certification program. Specifically, for hospitals and other California health facilities, pre-certified manufacturer listings are available at: http://www.oshpd.ca.gov/fdd/Pre-Approval/special_seismic_cert_pre-approval.html. If the manufacturer’s product is on the list, you may use it.
These IBC and OSHPD requirements for seismic certification and pre-approval of electrical equipment can be game changers, raising the level of “proof” that design, construction, and equipment specification as well as installation and operation will enable essential facilities to continue their intended function after a severe seismic event.
Special inspectors — not building code officials — evaluate facilities for compliance. If a facility does not comply, then the inspector has a legal right to withdraw the certificate of occupancy, even though the building may already be occupied.
Demonstrating the ramifications of failing to comply with current standards, engine-generator equipment installed in a new hospital constructed in St. Louis two years ago was red tagged for not being seismically qualified. St. Louis is located near the New Madrid fault area, which has generated the most severe ground acceleration during a seismic event in the United States (click here to see Map). In this particular example, the engine-generator manufacturer had to send a retrofit kit to the site that was field installed to bring the equipment into compliance.
In addition to dealing with the hassles of a red tagged job, the building owner and other plaintiffs, in turn, could sue project team members, including electrical contractors, for improperly designed and installed systems. As of May 2010, for example, Richard Berger, chairman of The VMC Group, Bloomingdale, N.J., said 38 lawsuits related to seismic design had been filed as a result of these new requirements. Project team members can minimize their exposure by ensuring critical equipment is specified and installed according to current standards.
It seems simple enough, but it isn’t always. Team members may believe they are protected by the master specification. However, if it isn’t written properly, it can be of little comfort when litigation arises. The bottom line is that project team members are joined at the hip, regardless of their role. The IBC’s Consequential Damage clause makes clear that the work of one is also the responsibility of others.
One reason contractors and other project team members may be unaware or confused about changes in the building codes — especially for seismic events — is that the handbook is for structural engineers, not electrical engineers. Seismic certification requirements for electrical equipment are not included in electrical handbooks.
All states have adopted one version of the IBC code or another. Nevertheless, many earthquake-prone communities in the country still do not have up-to-date building codes with seismic provisions.
One way to ensure properly written specifications is to review the structural engineer’s notes on a project. These notes will typically cover data on building type and its seismic design category, estimated required ground acceleration SDS, soil conditions, and other seismic design forces that the building and its critical equipment must withstand.
To qualify for seismic certification, critical systems and components must be subjected to simulated seismic events on a shake table, rather than just an engineering analysis. Compliance no longer can be achieved with engineering analysis alone. When qualifying on a shake table, testing must adhere strictly to AC156 criteria for non-structural systems and components.
The VMC Group, for example, certifies equipment on a tri-axial seismic simulator that punishes it with thousands of pounds of force. During such tests, mounting bolts take the brunt of the force. They are a critical factor in withstanding a seismic event, considering enclosures may sway 3 inches in all three axes (see Photo below). The top of the enclosure may move up to 4 inches. Test results should show the equipment’s ruggedness — mounting bolts remain seated, doors remain closed, and mechanically locked critical components, such as electrical contacts, do not jam.
This stop-action image shows a 4,000A bypass-isolation
automatic transfer switch being shake table tested. The
enclosure can move as much as 3 inches to 4 inches
during this type of test.
Bolts and braces also are important for another reason — to protect against consequential damage and the potential liability that could result. This type of damage occurs when non-essential equipment breaks loose during a seismic event and causes essential equipment to fail.
Chapter 17, Sec. 1708.4 of the IBC describes seismic qualification of non-structural components (i.e., mechanical and electrical equipment). Such systems encompass open gen-sets, enclosures, sub-base fuel tanks, remote radiators, automatic transfer switches and switchgear, batteries and battery racks, battery chargers, and day tanks. Depending on the equipment, some components may require isolation mounting as per Sec. 1708.5.
If the equipment is required to function to keep an essential facility online during a seismic event, is a life-safety component, or contains hazardous material, it’s assigned a seismic component Importance Factor (Ip) of 1.5. Section 13.1.3 of ASCE 7-05 acts as the guide for this rating. As noted earlier, Chapter 13 of ASCE 7-05 is the performance benchmark added in the IBC 2006 and 2009 building codes.
The Ip also applies to components in or attached to an Occupancy Category IV structure (IBC 2003/2006) or Category III structure (IBC 2000), which are essential to the continued operation of designated facilities. Occupancy Category is the new term for Seismic Use Group that was used in previous versions of the IBC. Category IV is essential facilities, such as hospitals, airports, and emergency services. Category III facilities are those that represent a substantial hazard to human life if they should fail. Examples are schools, day care facilities, power plants, and facilities with occupancy capacities exceeding 5,000. Categories II and I facilities and their equipment need to comply with seismic standards when the Ip is 1.5 due to life safety or hazardous material.
There are instances when an existing building could change categories. Berger recounted an experience by Goldman-Sachs with a 35-story building it owns in Jersey City, N.J. Because the brokerage house leased space to a 911 call response center, the category for the entire building changed to Occupancy Category IV. That made it an essential facility and subject to Category IV standards. In another instance, if a school’s gymnasium is designated as an “emergency shelter,” the gym can’t be considered an “island.” The entire school must then be categorized as Occupancy Category IV.
Equipment that needs to meet standards, however, must carry a certificate of compliance (C of C) that is submitted to the specifying engineer during submittal review and also submitted to the building official for approval. In addition, a label, mark, or other identification on the system or component must be affixed to determine compliance. This identification is proof to the inspector that the equipment that arrived on site is the same as what was submitted and approved during the submittal process. The C of C and the equipment label must contain the name of the certifying agency (or manufacturer may self-certify), the name of the manufacturer, the model designation of the equipment, and the performance criteria of the equipment (i.e., the seismic capacity of the equipment).
For his part, the building owner or his professional engineering representative must submit a statement of inspections identifying the building’s seismic-force-resisting systems, seismic systems, and architectural/electrical components requiring special inspections.
The key to satisfying the local inspectors or other Authorities Having Jurisdiction (AHJs) is to provide the exact conditions of the tested equipment. In fact, it is common for the AHJ to ask for the electrical product’s Seismic Test Report.
Increasingly demanding seismic standards and broader application of these rules add another dimension to the responsibilities of electrical contractors. The good news is they can minimize their exposure to risk and liability by familiarizing themselves with evolving seismic code standards, knowing whether or not project specifications account for ground acceleration and other seismic data for a site, working with project team members on a quality assurance program, and ensuring only properly certified equipment is installed.
Weber is a divisional engineer with ASCO Power Technologies in Florham Park, N.J. He can be reached at: Joe.Weber@emerson.com.