Spare Transformers
​Electricity moves through a complex transmission system. Transformers are located in substations near electric generating plants. In much the same way that a pump builds up the pressure of water in a hose, transformers step up the electricity voltage to levels ranging from 69,000 to 765,000 volts. From the transformers, electricity enters the transmission system.

In 2006, federal energy regulators approved the Spare Transformer Equipment Program (STEP), an electric industry program that strengthens the sector's ability to restore the nation's transmission system more quickly in the event of a terrorist attack. STEP represents a coordinated approach to increasing the electric power industry's inventory of spare transformers and streamlining the process of transferring those transformers to affected utilities in the event of a transmission outage caused by a terrorist attack.
Under the program, each participating electric utility is required to maintain and, if necessary, acquire a specific number of transformers. STEP requires each participating utility to sell its spare transformers to any other participating utility that suffers a "triggering event," defined as an act of terrorism that destroys or disables one or more substations and results in the declared state of emergency by the President of the United States.
Any shareholder-owned, government-owned, or rural electric cooperative utility in the United States or Canada may participate in the program. Currently 50 utilities, representing approximately 70 percent of the FERC-jurisidictional transmission system, are members.