Seismic Certifications – Changing the Face of Electrical Services?
Some areas of the country are more earthquake-prone than others, and this calls for different standards and regulations. Building codes have been tweaked to accommodate the needs of these locations, and it has even had an impact on electrical services. So what’s “shaking up” the industry? Read on to find out more thanks to EC&M magazine!
Seismic Certification Shakes Up Industry
Electrical contractors can minimize liability by installing only certified equipment
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.
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.
Real Life Risk
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. 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.
Shake, Rattle, and Roll
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. 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.
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.