(CNN) -- Improper wiring by military contractor KBR at U.S. bases in Iraq led to electrical shocks about once every three days for nearly two years, according to Defense Department documents obtained by CNN.

Sgt. Ryan Maseth, a 24-year-old Green Beret, died in a shower at his base in Iraq in January 2008.

Houston, Texas-based KBR, the military contractor responsible for maintaining and providing services at most of U.S. bases across Iraq, had "systemic failures" in its electrical work that threatened the life, health and safety of people inside the bases, according to the documents, from a violation report obtained by CNN.

There were 231 electrical shocks of personnel in Iraq from September 2006 through July 2008 in facilities maintained by KBR, the documents state.

KBR has been at the center of controversy surrounding the electrocution of soldiers on bases in Iraq. Much of the controversy has surrounded the electrocution of Sgt. Ryan Maseth, a highly decorated 24-year old Green Beret from Pittsburgh, Pennsylvania.

Maseth was electrocuted in a shower on a U.S. base in Baghdad, Iraq, on January 2, 2008.

At least 18 troops have been electrocuted in Iraq since 2003, and many of the electrocutions have been attributed to shoddy electrical work done on U.S. bases -- work managed by U.S. contractors -- according to Pentagon sources. Each of the electrocutions has occurred in different locations and under various circumstances.

The violation report shows that electrical shocks and problems with wiring and grounding continued for much of last year, long after Maseth's electrocution.

Heather Browne, a KBR spokesperson, said the company could not comment on the specific language in the document obtained by CNN because KBR had not seen it.

But the company has previously said that "KBR found no link between work it's been asked to perform and the reported electrocutions" and that "KBR remains committed to the safety and security of all employees and those the company serves. We have fully cooperated with the government when issues have been raised about work in Iraq and we will continue to do so."

On the death of Maseth, the company has said, "KBR's investigation has produced no evidence that KBR was responsible for Sgt. Maseth's death. We have cooperated fully with all government agencies investigating this matter and will do so in the future."

Last week, CNN obtained other documents that show the Army investigator assigned to look into Maseth's electrocution blamed KBR for the death, stating that she believed the cause was "negligent homicide" and that there is "credible information that KBR's negligence led to Maseth's death."

The revelations about the frequency of shocks on bases are found in the complete and detailed report that led to KBR's citation for being in serious violation of its contract several months ago.

At that time, the Pentagon's Defense Contract Management Agency gave KBR what is known as a "Level III Corrective Action Request." That is issued only when a contractor is found in "serious non-compliance" and is just one step below the possibility of suspending or terminating a contract, Pentagon officials said.

While that violation citation was previously known, the report's precise language and details of KBR's alleged "failures" were not known until now.

The 45-page report alleges KBR had improper electrical wiring, grounding and overall electrical problems across Iraq.

"The government found systemic KBR failures to properly ground and bond facilities -- failures that contributed to theater personnel receiving shocks in KBR maintained facilities on average once every three days" between September 2006 and July 31, 2008, the detailed report says.

That information, the report says, came from KBR's own statistical records.

"The conditions of these facilities created Life, Health, Safety (LHS) conditions for the occupants. The lack of grounding and bonding, among other electrical deficiencies" were "identified and confirmed by three separate independent inspection teams" from the U.S. Army Corps of Engineers, the U.S. Army Combat Safety Center and a multinational force working with fire and electricity, the report states.

"Most facilities inspected had electrical deficiencies because KBR failed to consistently follow contract standards every time it constructed or emplaced a facility, inspected a facility, responded to a service order request, or performed maintenance and/or repairs on facilities, generators and utilities," the report says.

Also, the report says, "the Government is unaware of any efforts undertaken by KBR to independently identify, assess, and implement corrective actions to its electrical support services or quality control inspection program as a result of the extensive number of electrical shock incidents. ... "

Sen. Robert Casey, D-Pennsylvania, said his office has received numerous anecdotal reports of U.S. military personnel continuing to receive electric shocks.

"While KBR continues to assure the American people that it has completed its own investigations and has found no evidence of corporate wrongdoing, the emerging facts prove otherwise," Casey said. "According to an internal investigation led by the Pentagon's contract auditors, we now know that KBR failed to comply with basic contractual requirements even while being rewarded with billions of dollars by U.S. taxpayers."

Casey called on the Pentagon "to treat this issue for the danger it represents." The Defense Department, he said, "has taken some encouraging actions [but] it needs to do much more."

"And it is high time that KBR begin to suffer real consequences for what I consider to be blatant contractual noncompliance," Casey said.

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