BC Hydro says extreme June heat may be to blame for damage to three submarine cables that provide power to Vancouver Island from the mainland.
The provincial Crown corporation said in a news release Monday that its monitoring system first detected a bulge and oil leak on July 8 in a cable that runs underwater from the Sunshine Coast to the island. After that initial discovery, two other cables were discovered over the weekend that are also bulging.
BC Hydro said the leaking cable was taken out of service, and the leak, which consisted of non-toxic mineral oil, has been contained. The load on the other two cables has been reduced, and they are being closely monitored.
The cables that were affected run from the Sunshine Coast, over Texada Island, then travel underwater to Nile Creek, near Qualicum Bay on Vancouver Island, where they connect above ground with the Dunsmuir Substation that then sends power up and down the island.
The cables, which are manufactured in Norway, each measure 15.24 centimetres in diameter. Inside is mineral oil that acts as a coolant surrounded by copper pipe that conducts electricity. The copper pipe is covered in lead, which is covered in plastic and the entire cable is then sheathed in concrete.
Ted Olynyk, BC Hydro's community relations manager for Vancouver Island and the Sunshine Coast, told CBC News Tuesday morning that the cable leak happened above water close to a terminal point on Texada Island, so repairs on that cable can be done above ground.
He said fixing the cables is complicated work, but islanders should not worry about losing power.
"We have enough to meet our load," said Olynyk, which he said is roughly 1,000 megawatts at this time of year.
He said the island is still receiving sufficient power from another set of cables that runs from Tsawwassen to Duncan, can produce its own on-island power and can rely on independent power producers on the island to help fill any gaps.
However, as a precaution, BC Hydro has told its largest industrial customers on the island they may need to reduce their power use.
"We are just advising that it may come to that," said Olynyk.
While an investigation is underway to determine what caused the damage, Olynyk said the cables were inspected in May and again in mid-June just before the recent heat wave blanketed B.C.
When last inspected, Olynyk said there were no "abnormalities" seen on the cables.
Temperatures in late June shattered previous heat records this year — with the mercury hitting 40 C in Vancouver and substantially higher in the Interior.
"I think it's pointing to that direction [the heat wave] at this point," said Olynyk, adding he does have concerns for the future of the infrastructure if such heat events become more common.
According to Olynyk, about 70 per cent of the island's electricity is supplied by cables coming from the mainland.
B.C.'s high-voltage transmission system consists of more than 18,000 kilometres of power lines and underwater cables. Seventy to 80 per cent of the province's electricity is consumed in the Lower Mainland and on Vancouver Island.
Electricity is supplied to the Lower Mainland and Vancouver Island from the Peace River hydroelectric system through Kelly Lake Substation, and from the Columbia River system through Nicola Substation.