Meanwhile, energy to the area continued to be supplied by another 11kV cable until it too suffered a fault at around 8pm, cutting off power for 2,250 households.
“CLP Power conducted an investigation into the faulty cables and confirmed that each cable had a joint that had previously been interfered with by external factors, which gradually degraded the insulation and led to the two sequential faults on that day,” the company said.
The disruption affected four residential buildings including Lions Rise, Mei Tak House in Mei Tung Estate, Lung Kwong House in Lower Wong Tai Sin Estate and some neighbourhood shops, with at least four reports of people trapped in lifts.
The company said power for all affected areas was restored past midnight on June 13 following urgent repairs.
“To alleviate concerns about power supply in [the] Wong Tai Sin area, CLP Power has taken additional measures to enhance patrols of cable routes and power equipment in the district,” the company said, adding that it would complete inspections for all customer substations in the area by mid-July.
“We will also increase inspections of third-party construction sites to remind workers to avoid disrupting underground cables to prevent damage.”
CLP Power, which supplies Kowloon, the New Territories and most outlying islands, logged five supply disruptions in the first four months of this year, including three voltage dip incidents that left more than 200 residents trapped in lifts.
An existing penalty mechanism for outages requires electricity providers to pay fines based on the duration of the incident and the number of people affected.
The policy was among measures announced in December following the government’s interim review of its “scheme of control” agreements with the city’s two suppliers, CLP Power and HK Electric.
Under the mechanism, CLP Power must pay a fine of HK$20 million (US$2.56 million) or a deduction of 0.015 per cent from its permitted return if it records 15 million minutes of power disruptions in a year.
HK Electric, which supplies Hong Kong and Lamma islands, also faces a fine of HK$20 million if it has 10 million minutes of outages in a year.
Both companies can receive a 0.015 per cent incentive if they restore the supply within 65 minutes of an outage and maintain a yearly average reliability rate of 99.996 per cent or above.
The next interim review for the two energy firms will take place in 2028.