Ten thousand people are said to have been affected by the power outage there.
There have been no mentions of injuries, though a crew was reportedly inside the substation when the explosion happened.
BC Hydro officials said power was back online in Kamloops the following day.
In Vancouver, BC Hydro scrambled to get the power restored to dozens of skyscrapers and businesses that were evacuated after a Monday morning fire caused a blackout.
Police had been concerned that the blackout would cause overnight threats to "people and property" in the darkened city. However Const.Tim Fanning, with the Vancouver police, said Tuesday there had been no incidents.
"We had extra officers patrolling the streets and many businesses hired extra security guards," said Fanning. "We will continue to have extra officers until the power is back on."
BC Hydro spokeswoman Susan Danard said it could be some time before power is restored. Crews have to pull 14 damaged cables out of a manhole, flush out the underground vault thoroughly, then bring in new cables and splice them before power can be reconnected.
"Unfortunately, we are looking at a fairly extensive repair job," Danard said. "It could be a couple of days before we've completed all the splicing of all the new cable."
Crews were having difficulty accessing the manhole where the fire started because of smoke and heat. BC Hydro said the damage will likely be "significant."
Police said many traffic lights are operating but some businesses remain closed.
About 2,200 customers were without power overnight in downtown Vancouver Internet services for many companies also blacked out July 14 when one of seven backup generators at Harbour Centre, a major telecommunications and Internet hub in Vancouver, conked out. Robson Communications Inc. said several hundred Internet servers lost power. Many of those organizations affected weren't even in Vancouver.