Some of the BBC's radio and television services, including Radio 4, Five Live and News 24, were forced off air by a power cut and a fire alert on Friday.
BBC News 24 moved to an alternative studio
Radio 4's Today programme was off air for 16 minutes from 0753 GMT.
News 24 had to broadcast from the BBC One Breakfast sofas before moving to different studios in London.
An electrical problem in BBC Television Centre, west London, caused the power cut, BBC Director of News Richard Sambrook said.
The fault caused equipment to overheat, setting off the fire alarm - but there was no fire, Mr Sambrook said.
"I am told the cause of the problem was an electrical fault... which took out all technical power and also prevented the diesel back-up generators from working.
"The problem generated the smoke that was encountered in some areas, but there was no fire."
He also praised staff who made sure normal service was resumed as quickly as possible.
Philip Hayton earlier hosted News 24 from the Breakfast studio
The power cut and fire alarm forced parts of TV Centre to be evacuated twice.
BBC One's One O'Clock News was broadcast from alternative studios but the Six and Ten O'Clock bulletins are expected to come as normal from TV Centre.
Other services, such as Five Live, Radio 4 and News 24, also returned during the afternoon.
News 24 was expected to re-launch with a new look and agenda from 1 December but that has now been put back to the 8 December so that any power problems can be fully fixed.
When the problem occurred, the Today programme was interrupted during an interview with Culture Secretary Tessa Jowell, with music played in the show's place during the stoppage.
When the programme returned, Foreign Secretary Jack Straw, who was being interviewed, joked: "It takes me back to the 1950s when they used to put the scorecard on the television.
"Maybe it's a not-so-subtle bid by the BBC for an increase in the licence fee."
BBC World had to play recorded news packages for a time.
And BBC One's Breakfast presenters had to keep broadcasting on News 24 for an extra half hour, until 0930.
After a pre-recorded edition of Hard Talk, News 24's Philip Hayton then took over presenting duties from the Breakfast studio before handing over to colleagues based elsewhere.