The hugely popular attraction had to ask shoppers and visitors to leave at around 3pm today (Saturday) because it had no electricity.
It is understood to have re-opened, following a health and safety check, at 5pm
Chief Executive of The Piece Hall Trust Nicky Chance-Thompson said the power cut was down to a National Grid outage.
Punk legends Buzzcocks are due to play at The Spiegeltent in The Piece Hall tonight.