KBR itself told the Pentagon in early 2007 about unsafe electrical wiring at a base near the Baghdad airport, but no repairs were made. Less than a year later, a soldier was electrocuted in a shower there.

“I don’t feel like they did their job,” Carmen Nolasco Duran of La Puente, Calif., said of Pentagon officials. Her brother, Specialist Marcos O. Nolasco, was electrocuted at a base in Baiji in May 2004 while showering. “They hired these contractors and yet they didn’t go and double-check that the work was fine.”

The Defense Contract Management Agency, which is responsible for supervising maintenance work by contractors at American bases in Iraq, defended its performance. In a written statement, the agency said it had no information that staff members “were aware” of the Army alert or “failed to take appropriate action in response to unsafe conditions brought to our attention.”

Keith Ernst, who stepped down Wednesday as the agency’s director, said, though, that the agency was “stretched too thin” in Iraq and that the small number of contract officers did not have expertise in dealing with so-called life support contracts, like that awarded to KBR to provide food, shelter and building maintenance. “We don’t have the technical capability for overseeing life support systems,” he said.

For its part, KBR, which until last year was known as Kellogg, Brown and Root and was a subsidiary of Halliburton, denied that any lapses by the company had led to the electrocutions of American soldiers. “KBR’s commitment to employee safety and the safety of those the company serves is unwavering,” said a spokeswoman, Heather Browne. “KBR has found no evidence of a link between the work it has been tasked to perform and the reported electrocutions.”

Image Jeffrey Bliss, an electrician who worked for KBR, the military contractor.

Ms. Browne declined to respond to the specific accounts of former KBR electricians.

Those electricians have a ready response to anyone who suggests that poor electrical work might be considered an unavoidable cost of war. “The excuse KBR always used was, ‘This is a war zone  what do you expect?’ ” recalled Jeffrey Bliss, an Ohio electrician who worked for the company in Afghanistan in 2005 and 2006. “But if you are going to do the work, you have got to do it safe.”