Services at the Prince of Wales Hospital were interrupted by a power blackout yesterday, caused by damage to two underground high-voltage cables. The blackout occurred at 3:20pm when construction workers, who were doing renovation work for the hospital, accidentally damaged the cables, a spokesman for the hospital said. Power was restored two hours later. Patient visits were not allowed during the blackout. The hospital spokesman stressed that all medical facilities, including operating theatres, casualty wards and the intensive care unit had not been affected as backup electricity sources were activated 10 seconds after the blackout hit the hospital. He added that the hospital had already asked the construction company to compile a report explain what happened. A CLP Power spokeswoman said two mobile power generators and maintenance workers had immediately been despatched to the hospital, once they were informed of the blackout.