Entering Rover Station is like stepping into a different ecosystem — and into a piece of Winnipeg's past.

Inside, the air is warm and stale. Sunlight shines through broken windows and a blackish-grey dust coats every surface, even the walls. Pigeons fly near signs warning of electrocution and asbestos.

The building smells like a place long neglected.

It's musty, just like "grandpa's cellar," says Manitoba Hydro spokesperson Bruce Owen. "Our new buildings don't have this smell."

Rover Station, a three-storey red brick building, sits on the bank of the Red River in Winnipeg's North Point Douglas neighbourhood. From the outside, it could be mistaken for a school, with its stone front steps and oversized windows.

Owen says sometimes, it's used as a stand-in for prisons in movie shoots. The substation is surrounded by concrete walls and barbed wire.

Manitoba Hydro gives CBC a rare look inside one of its oldest buildings. 1:59

Inside Rover, transformers hum away as they have for 107 years.

The equipment takes power from the Pointe du Bois Generating Station on the Winnipeg River, about 160 kilometres northeast of Winnipeg, and feeds it out, at a lower voltage, to Winnipeg's inner city.

If Rover Station suddenly went offline, customers in Point Douglas and across the river in Elmwood could be in the dark for hours, if not days, depending on the time of year.

Growing demand for power downtown, especially since the construction of the Bell MTS Centre and the RBC Convention Centre, means Hydro is unable to take Rover offline until the Crown utility can build capacity at other substations, like Adelaide Station downtown and Martin Avenue in the Chalmers neighbourhood.

But Rover is crumbling.

Manitoba Hydro is gambling it will hold on until 2020, when they hope to finally deem it surplus.

A costly inheritance

Like many electricity utilities in Canada, Manitoba Hydro has amassed a huge liability in the form of old, broken stuff.

Hydro estimates what it calls "system renewal" will cost $7.3 billion over the next 20 years.

"Much has been discussed about the large capital projects like the Bipole III transmission line and the Keeyask Generating Station," Owen says.

"Somewhat overlooked in the discussion is the challenge facing us of not only replacing aging assets like Rover, but modernizing and expanding our system."

That work includes replacing aging buildings like Rover, along with hydro poles, manholes, spillways, transmission lines and other infrastructure long past, or approaching, its best-before date.

Rover Station was built in 1911 at the height of Winnipeg's economic boom. The Exchange District was bustling, Winnipeg's economy was breeding millionaires and citizens were demanding the new, brighter electric lights they saw popping up in other cities.

Rover Station was built in 1911 and brought electric street lights to Winnipeg. (Manitoba Hydro)

The main hydro company at the time, the Winnipeg Electric Street Railway Company (which ran the streetcar line and powered downtown elevators), quoted the city too hefty a price to electrify street lights. So city council created the Winnipeg Hydro-Electric System to do it themselves.

In less than five years, the city had 35,000 customers connected to the public power grid. The utility would eventually become Winnipeg Hydro, which was bought by Manitoba Hydro in 2002.

Rover Station remained important in Winnipeg for decades. After the 1950 flood, the city built the prison-like concrete wall around it as a defence against the sometimes capricious Red River.

Hard hats required

There are ground rules for tours at Rover Station.

Visitors must wear hard hats and safety glasses. People must walk slowly inside yellow painted lines and avoid touching anything that's not a doorknob or railing.

"In a station like Rover you can reach out and touch live voltage in many areas. In the new stations you can't do that. There are barricades in place to keep everybody safe," said Manitoba Hydro electrical technician Al Dacombe.

A stumble or a misplaced hand, and a person could be burned from the inside out in an instant.

The largest room in Rover is the high-tension, or high-voltage, area. The space is about the size of a school gym. It's filled with transformers, cables and what look like oversized spark plugs.

On the wall above, Dacombe points out two small orange lights, flickering like narrow flames. They indicate two live 66-kilovolt transmission lines are still in service.

Two other transmission lines taken offline in recent years and rerouted to transformers housed in green hydro boxes outside.

Up a wrought iron staircase, Dacombe shows CBC the control room. When Rover Station was first built, and for decades following, the room was staffed 24 hours a day, seven days a week. Today, a Hydro worker stops in once a month.

The room is a living museum of hydro technology from the last 100 years.

On one wall, black plastic boxes contain Rover's modern, solid-state digital protective relays — machines that can switch off power or trip a line in milliseconds. Across a large desk, ammeters — meters that measure current flow in an electrical circuit — are stamped with brass plaques indicating they were patented by the Westinghouse Electric Company in October 1897.

"It is a beautiful piece of equipment that would most likely still function very accurately," said Dacombe.

A 4,000-volt circuit breaker in the basement of Rover Station exploded in2016 sending a Hydro worker flying into the air. He survived because he was wearing a mandatory bomb suit. 1:03

In the corner of the control room there's a trap door in the floor. The escape is just big enough to fit one person at a time. There are signs throughout Rover warning employees to leave the station immediately if the alarm system goes off.

Now disabled, Rover's old emergency system gave workers just 30 seconds to escape before they would risk suffocation from the release of carbon dioxide gas.

Unlike water, the gas could safely extinguish a fire near electrical equipment by displacing oxygen — but it could kill anyone left inside.

A confusing labyrinth

Much of Rover is a confusing labyrinth of hallways, staircases and poky, small rooms. Disconnected toilets sit on their side. There are piles of forgotten fuses and yellowed typewriter paper.

In the basement, joists hold up a floor no longer strong enough to support the weight of equipment.

Cracks appear in the ceilings, floors and across walls. Parts of the building, CBC was told, are so structurally unsound people are barred from going inside.

Paint above is flaking — a worrisome indication of moisture in a building buzzing with enough electricity to power whole neighbourhoods.

"This building should have been replaced a long time ago," Owen says looking at the pigeon droppings and paint chips inside Rover.

"It's not immediately dire but the potential is there for it to be."

That potential is very real.

About five years ago, Dacombe told CBC News a current transformer blew up in the high-voltage room, sending shards of porcelain in every direction and blackening the ceiling.

No one was inside the building at the time, which was lucky.

"It can be very dangerous," said Dacombe, who once responded to a flood at Rover in the middle of the night when the building's water-cooling system was still in use. Hydro has since switched to fans to cool the equipment.

"With aging infrastructure, you just never know when it can blow."

Before it was disabled, Rover Station had a fire suppression system that pumped carbon dioxide gas throughout the building. It displaced the oxygen and put out any fires, but if workers did not escape in time they could suffocate and die. 0:35

In 2016, a 4,000-volt circuit breaker in the basement exploded, sending a Hydro worker flying into the air. Walls around the explosion are still black with ash.

The worker survived because he was wearing the 40-calibre bomb suit required to work on the equipment, said Dacombe.

"He had a couple singed boot laces but other than that he was physically OK."

A time bomb and a juggling act

There are rooms so crammed with live equipment they require workers to put on a bomb suit just to step inside.

That includes the building's local service room. All of Rover's power, lighting and heating comes through a system that looks like a smaller version of Dr. Frankenstein's lab.

Dacombe calls the four-kilovolt equipment inside a "ticking time bomb."

Its breaker (kind of like the fuse box in your house) is insulated with oil, but workers have no safe way of knowing how much oil is left. The only way they could check would be to completely de-energize Rover.

"We don't go in here if we don't have to," he said from the doorway.

The plan for now, Dacombe said, is to hope the breaker holds until Hydro is ready to decommission the building.

He shrugs at the prospect. The breaker just one of the building's many flaws out of his control.

Owen acknowledges the unpredictability and hazards of equipment at Rover.

"When we talk about replacing this building the paramount issue is the safety of our employees," he says.

But, aside from Rover, there are many other environments that pose safety risks to hydro workers — hence the $7.3-billion price tag to fix it all.

"It's a juggling act," said Owen. "There is so much that we need to do, not only from this building but from unsafe manholes. We have a lot of underground equipment in the downtown area we need to repair because our employees are also in there."

In the end, Hydro expects it will cost $12.7 million to decommission Rover Station.

The Crown corporation will save any usable equipment left inside and then it plans to demolish Rover. Hopefully that will happen by 2020 but Owen resists giving an absolute deadline.

"It would be a shame to see it in rubble on the ground," says Dacombe. "But it's definitely overdue."