Bonnie Horton knew right away that something was wrong.

“We heard ‘pop pop pop pop pop’, and all of a sudden, up by the roof, there was smoke,” she says.

What she heard was a power surge caused by an electrical overload at her Cambridge housing complex.

Workers had arrived at Robert Kerr Manor on Thursday to do scheduled maintenance work.

Realizing that the work was going to take longer than the eight hours they’d told the community’s residents it would, they brought in a generator to keep the lights on.

When they went to fire that generator up, it created a power surge – frying appliances across the 42-unit complex.

“What we’ve been told is that it wasn’t the appropriate generator for that building,” says Deb Schlichter, the Region of Waterloo’s director of housing.

Horton’s stove and microwave stopped working. So did most of her lights.

In another unit of the Concession Street complex, Jeremy Do Couto has two working light fixtures – but his appliances are toast.

He recalls being frightened when the surge hit.

“I didn’t know if it was gunshots or natural sparks from the wiring,” he says.

A second generator was brought in later in the night, and the workers returned Friday.

Also at Robert Kerr Manor on Friday were regional housing staff, visiting each unit to get a clearer sense of how many appliances are no longer working.

While the region owns the building’s refrigerators and stoves, smaller appliances like microwaves and TV sets are owned by the tenants.

Representatives of the region and Selectra Contracting, the electrical company that was doing the work and brought in the generator, say all affected tenants will eventually be compensated for their losses.