WASHINGTON - Shoddy electrical work by private contractors on U.S. military bases in Iraq is widespread and dangerous, causing more deaths and injuries from fires and shocks than the Pentagon has acknowledged, according to internal Army documents.

During just one six-month period -- August 2006 through January 2007 -- at least 283 electrical fires destroyed or damaged U.S. military facilities in Iraq, including the military's largest dining hall in the country, documents obtained by The New York Times show. Two soldiers died in an electrical fire at their base near Tikrit in 2006, the records note, while another was injured while jumping from a burning guard tower in May 2007.

And while the Pentagon has previously reported that 13 Americans have been electrocuted in Iraq, many more have been injured, some seriously, by shocks, according to the documents. A log compiled this year at one building complex in Baghdad disclosed that soldiers complained of receiving electrical shocks in their living quarters almost daily.

Electrical problems were the most urgent noncombat safety hazard for soldiers in Iraq, according to an Army survey issued in February 2007.

It noted "a safety threat theaterwide created by the poor-quality electrical fixtures procured and installed, sometimes incorrectly, thus resulting in a significant number of fires."

The Army report said KBR, the Houston company that is responsible for providing basic services for U.S. troops in Iraq, including housing, did its own study and found a "systemic problem" with electrical work.

But the Pentagon did little to address the issue until a Green Beret, Staff Sgt. Ryan D. Maseth, was electrocuted in January while showering. His death, caused by poor electrical grounding, drew the attention of lawmakers and Pentagon leaders after his family pushed for answers. Congress and the Pentagon's inspector general have begun investigations, and this month senior Army officials ordered electrical inspections of all buildings in Iraq maintained by KBR.

"We consider this to be a very serious issue," Chris Isleib, a Pentagon spokesman, said Thursday in an e-mail message, while declining to comment on the findings in the Army documents.

Heather Browne, a KBR spokeswoman, would not comment about a company safety study or the reports of electrical fires or shockings, but she said KBR had found no evidence of a link between its work and the electrocutions. She added, "KBR's commitment to the safety of all employees and those the company serves remains unwavering."