council chiefs today admitted they could not guarantee there will not be a repeat of the power blackout which forced the cancellation of a showpiece Festival concert at the Usher Hall.
Electrical engineers called in to find out what caused the power failure on Tuesday night have still not traced the fault, raising fears of further disruption to the programme at the prestigious venue.
The hall has a packed Festival schedule with high-profile concerts every night.
Power was restored to the council-owned venue after Tuesday night’s cancellation, which saw more than 1200 disappointed concert-goers sent home.
Engineers, however, have so far been unable to find what went wrong and sort it, prompting concerns that there could be another power failure.
Council chiefs are now expected to bring in specialists to identify the problem and provide a long-term solution.
A spokesman said: “We still don’t know exactly what caused this incident. There is nothing apparent they can just fix.
“We have stand-by arrangements in place should there be a recurrence of the issue.”
Around 1250 concert-goers who were due to hear a performance by the London Philharmonic Orchestra were left outside the Usher Hall on Tuesday until learning about 20 minutes after the starting time that it had been cancelled.
Tory councillor Jason Rust said: “It is very concerning they have not yet located the source of the problem because it means there is no guarantee it won’t recur.
“It is especially worrying at such a busy time with so many people visiting Edinburgh for the Festival, as well as local people going to the Usher Hall.
“And there is the potential for serious reputational damage if it is does recur.”
A £37.5 million refurbishment of the Usher Hall was completed in October 2010, but council officials said the electrics had been renewed as part of the first phase of the revamp back in 1999/2000.
The council’s culture and leisure leader Richard Lewis said: “It is a concern but staff have been working hard to resolve this so that we can be confident there won’t be a recurrence.”
A spokeswoman for the Festival: “Huge efforts are being made to fix the issue permanently. In the meantime, the power system is currently working and concerts are going ahead as scheduled.”