ve energy and power systems for data centers. A key task in designing data centers is determining which devices or elements represent single points of failure that have the potential to put the entire data center out of service. Power cuts and interruptions, fire, and natural disasters such as hurricanes all have the potential to shut down computer operations. Human error can also cause failures. Thus, in addition to saving energy costs, enterprises and carriers with mission- critical data centers must decide where to spend money on redundancy and protec- tion from catastrophic failures. Because loss of a UPS can bring down a data center, Data Centers and IP Private Branch Exchanges many organizations consider redundant UPS service, as well. This can mean two UPS devices connected to the same electrical feed or the more costly option of two electri- cal feeds, each with its own UPS device. If one electrical cable is cut, the data center will fail over to the other one. Taking Steps to Ensure Adequate, Lower-Cost Power In an effort to save money on electricity, some large enterprises have applied for and received permission from the United States Federal Energy Regulatory Commission (FERC) to become wholesale providers of electricity. By doing so, they can purchase bulk supplies of power at low rates. In addition to saving money on power purchases, this ensures that they have an adequate supply of electricity for their own power needs. Examples of companies that have been approved by FERC include Google, Safeway, Inc., Kimberly-Clark Corporation, Alcoa, and Wal-Mart. None of these companies have stated an interest in reselling electricity on a retail basis. While it's not expected that smaller organizations will follow this route, this does point out the efforts that large, multisite firms will take to ensure an adequate supply of electricity at the lowest possible rates. To further ensure a steady supply of power, companies also purchase power from multiple power generating companies over dif- ferent power feeds.