[caption id="attachment_12979" align="aligncenter" width="400"] Arc flashes cause more than 2,000 industrial injury accidents per year: U.S. MSHA[/caption] The massive, state-of-the-art NSA datacenter in Bluffdale, Utah has been shut down just prior to its official opening following the latest in a 13-month series of explosive failures in its backup-generator system. Those issues have caused hundreds of thousands of dollars in damage. The failures have delayed the opening of the controversial datacenter for at least a year, according to an Oct. 7 Wall Street Journal story that cited project documents and unnamed officials as its primary sources. Electrical problems have caused 10 "meltdowns" during the past 13 months, primarily due to arc fault failures in the backup generators, which the Journal had one official describing as "a flash of lightning inside a 2-foot box" that lead to "fiery explosions, melt metal and cause circuits to fail." The problems were discovered as part of the inspections and testing required before the building could be accepted as completed by Federal authorities. "During the testing and commissioning of the Utah Data Center, problems were discovered with certain parts of the electrical system," according to a report from the Army Corps of Engineers, which conducted the inspection. "The Corps is ensuring [the Utah Data Center] functions as required and that it will be completely reliable prior to releasing the project to the customer," according to Norbert Suter, Corps's chief of construction operations, in a project document quoted in an Oct. 8 WSJ blog. Some engineers have suggested replacing the problematic portions of the backup network, but that "gained little traction when project officials realized it would cost hundreds of millions of dollars," the Journal reported today. Arc faults are a form of electrical short circuit in which the flow of power leaves low-resistance wiring and arcs through a less-conductive medium, usually air or air mixed with vaporized particles of the short-circuited terminal, according to according to a 2005 white paper from Glenn Walls of Professional Power Systems, PLC. The resulting "arc flash" can pull hundreds or thousands of times the current normally flowing through the connection, causing a "ball of fire and molten metal as well as a pressure force or blast" at temperatures as high as 16,000 degrees Fahrenheit, Walls wrote. Arc flashes make up "a substantial portion of the injuries form electrical malfunctions," according to a 1981 IEEE primer on the phenomenon written by Ralph H. Lee. "The extremely high temperature of these arcs, about four times as high as that of the sun's surface can cause fatal burns at up to about five feet and major burns up to a 10 foot distance." Arc faults can be prevented using Arc Fault Circuit Interrupters (ACFI) – circuit breakers whose circuitry is designed to identify problematic arc conditions and cut power to the circuit. ACFIs are not able to detect all conditions that could lead to arc faults, however, and are relatively poor defense in high-voltage environments that use relative high-resistance terminals. The Journal wasn't specific about what parts of the back-up generator systems were causing the problems, but did say the generators had failed several times and the cooling systems on the server floors had not yet been tested. An NSA spokesperson told the Journal "the failures that occurred during testing have been mitigated," but other sources said there were disagreements about the source of the problems and whether repairs were sufficient. The datacenters in the $1.4 billion facility south of Salt Lake City are designed to pull 65 megawatts of electricity for normal operation – about the same as a small city. The Journal implied the problems were related to sloppy design or materials, however, caused by the short construction deadlines and scale of the design.   Image: U.S. DoL Mine Safety and Health Administration