The man was standing on a ladder and performing an electrical test when he touched the power line, said Neal Strasser, a battalion chief with the Arlington Fire Department.
The man became wedged between the ladder and the stadium wall. A co-worker carried him to the ground and tried to revive him, Strasser said.
The Tarrant County Medical Examiner's Web site identified the man as Timothy Mackinnon, 45, of Arlington. He worked for JMEG Electric, a subcontractor hired by the stadium's general contractor, Manhattan Construction.
The accident happened around 11 a.m. The fire department received an emergency call at 11:05 a.m. and arrived within five minutes, but revival attempts at the scene were unsuccessful. Mackinnon was pronounced dead at Arlington Memorial Hospital.
"The workers were visibly upset," Strasser said.
Work on the stadium in suburban Arlington stopped within an hour of the accident, and the job site will remain closed the following day, Cowboys spokesman Brett Daniels said.
JMEG didn't immediately respond to a phone message left by The Associated Press. In a statement from Manhattan Construction, the company described Mackinnon as a journeyman electrician and said its employees were "deeply saddened."
"Our focus right now is with the family and friends of this individual as well as on the investigation of the incident," the statement said.
The cause of the accident is unknown, but the construction companies are cooperating with investigations being conducted by police and the Occupational Safety and Health Administration, according to a statement from Manhattan that was released by the Cowboys.
The death comes two days after a crane accident at the construction site sent three workers to the hospital. Two were treated and released, while the third, Wesley Harlow, was in serious condition Saturday, said a spokeswoman at Baylor University Medical Center.
OSHA officials were at the site at the time of the incident, still investigating the Thursday crane accident, Daniels said.
"They were able to immediately start checking things out," Daniels said. "But the actual cause is still to be determined."
There have been at least two other accidents at the stadium site that left workers hospitalized.
In August, a crane hook hit a worker in the back. He was sent to the hospital and released the next day. In January 2007, a stadium worker fell 20 feet through a hole between stadium levels. He was hospitalized in critical condition but recovered and later returned to work.
The more than $1 billion retractable-roof stadium has been under construction for two years and is scheduled to open for the 2009 season and host the 2011 Super Bowl. The 80,000-seat stadium is expected to be the world's largest column-free room, with retractable panels.