Police and Hydro One are investigating the theft of copper grounding material from one of the utility's distribution centres around 10am Friday.
Utility spokesperson Tiziana Baccega Rosa says the theft caused a power outage to about 1,800 customers in the Forest area.
She says it's extremely dangerous to be around their equipment.
"It puts a lot of people in danger. It's not just our workers, it could be the public who are passing by, it could be a kid that walks into the fence if it's cut," says Baccega Rosa. "We ask if you ever see suspicious behavior to report it to the police."
Baccega Rosa says they'll be replacing the copper with a composite product that is less valuable to thieves.
Service to all customers was expected to be back by 4:15pm.
