Half of the stadium lights went out with 13:28 to go in the third quarter and the Baltimore Ravens holding a 28-6 lead over the San Francisco 49ers, leading to a 34-minute delay in Sunday's NFL championship tilt.
The Ravens held on for a 34-31 victory over San Francisco after the power was restored.
Entergy and Superdome management company SMG said in a joint statement the cause of an "abnormality" in the power flow remained unclear Monday, but it was determined it originated where the Superdome equipment intersects with Entergy's feed into the facility.
"A piece of equipment that is designed to monitor electrical load sensed an abnormality in the system," the statement indicated. "Once the issue was detected, the sensing equipment operated as designed and opened a breaker, causing power to be partially cut to the Superdome in order to isolate the issue."
Entergy and SMG said they will "continue to investigate the root cause of the abnormality."
NFL Commissioner Roger Goodell told reporters the outage was not related to the halftime show staged by pop singer Beyonce.