Transfer Switches Exceed Seismic Requirements

By Consulting Specifying Engineer Staff April 23, 2007

Independent tests show that transfer switches from ASCO , Florham Park, N.J., exceed the International Building Code requirement by operating during a simulated severe seismic event. The significance of this test is that the requirement only requires the transfer switch to operate before and after an event. IBC 2003 certification for severe seismic events is critical for states such as California, Washington, Nevada, Idaho and Colorado.

ASCO had its transfer switches tested because IBC requirements now demand that transfer switches be subjected to simulated seismic events, rather than an engineering analysis. The IBC 2003 edition states “every manufacturer providing a piece of

The company’s

Transfer switch mounting bolts and enclosures took the brunt of the force. They are a critical factor in withstanding a seismic occurrence. Test results show the equipment’s mounting bolts remained seated, doors remained shut and the system remained operational during and after the test. The design of mechanically locked critical components, such as main contacts, prevents jamming. The new requirements required bracing and other reinforcement to the enclosure, which is available as an option, Accessory 125.

The certificate of conformance from the testing lab states that the ASCO Power transfer switch “meets or exceeds the requirements of the 2003 International Building Code for Importance Factor 1.5 Electrical Equipment, for use in Zone 4 or less severe seismic regions.”

It is critical for the power transfer switch—the “brains” of any emergency power system—to not only to immediately sense loss of utility power, but to start the engine-generator and feed electrical power to its loads as soon as possible. For example, emergency power for a hospital power needs to be restored to critical loads within 10 seconds after loss of utility power. Failure to restore power could produce life-threatening consequences.

Besides hospitals and other healthcare facilities, the IBC designates a number of specific buildings and structures as essential facilities. They include but are not limited to fire, rescue, and police stations, designated earthquake and hurricane shelters (i.e. public schools), power generating stations,