Heathlands Jewish Care Village in north Manchester was without power for three hours on Tuesday while essential electrical repairs were carried out.
Emergency measures were in place for a six-hour power outage at the Prestwich buildings housing close to 200 residents and the Federation of Jewish Services' offices.
But engineers were able to halve the blackout period.
Eighteen months' rewiring work has been part of a £7.5 million revamp of the care campus. The FJS anticipates £60,000 in annual energy savings.
In preparation for the shut-off, 50 battery lanterns were positioned in key areas. Electric hoists and air pressure beds were fully charged in advance. With elevators not functioning, residents were given the option of staying in their rooms or in a communal area. Senior staff were given mobile phones to replace landlines.
"We have to upgrade and update the standard of the environment," explained Joyce Khan of the FJS. "It is about looking after the residents and staff and having a building that is fit for purpose. More visible work to the surroundings will be seen from here on and we have appointed a project manager to oversee developments."