NEW ORLEANS (February 8, 2013)—Entergy New Orleans says the cause of the Super Bowl blackout was a faulty device that had been installed to prevent a failure of electric cables leading to the Superdome.

Entergy officials said the device, called a relay, had been installed to protect the stadium from a cable failure between the company's incoming power line and lines that run into the stadium.

Company officials said the device performed without problem during January's Sugar Bowl and other earlier events.

They said the device has been removed and replacement equipment will be installed.

The power failure cut lights to about half of the stadium for 34 minutes, halting play between the Baltimore ravens and San Francisco 49ers.

Earlier, the utility and the company that manages the stadium said they would hire a third-party investigator to pinpoint the cause of the blackout and the head of the utility told New Orleans City Council members Friday the investigator might still be hired.

An electrical engineering professor at Louisiana State said the relay device is common at massive facilities like the Superdome.

"It's not unusual for them to have problems," he said.

The manufacturer of the device said Friday a low trip setting caused the partial blackout.

The statement from S&C Electric Co. of Chicago said the outage could have been avoided if the operator of the relay device had set the trip threshold higher.