The Louisiana Superdome is powered off the city's-grid (AC current), which fuels: stadium-lighting, radio/t.v. outlets, etc. The Superbowl-Halftime show (special-effects) however, should of been switch onto a separate : DC-power-supply (generators)- to prevent 'electrical-backdrafts'(blowing circuits/transformers) < which caused the stadium-blackout' ten-minutes later...