(CNN) - A design flaw and human error caused the blackout at the Mercedes-Benz Superdome during Super Bowl XLVII, according to an independent analysis released by utility company Entergy New Orleans.
Officials say a recently installed relay had a "design defect" that caused it to trip in an unpredictable way.
Inadequate communication between the manufacturer and the utility company also played a role.
Power was cut off to half the arena early in the third quarter in the game between the Baltimore Ravens and San Francisco 49ers.
The game was delayed for 34 minutes.