26 August 2022
CLP Power Hong Kong Limited (CLP Power) today (26 August) made public the investigation report on the cable bridge fire incident in Yuen Long which occurred on 21 June 2022. According to the comprehensive investigation and analysis, it is highly possible that a fluorescent light installed below the cross beam within a section approximately four metres from the junction between the steel bridge and the concrete chamber at Kwong Yip Street caught fire and ignited the nearest pilot cable below, with the fire spreading to the adjacent pilot and power cables.
CLP Power is committed to providing customers with a highly reliable power supply. This cable bridge fire incident was extremely rare and affected the power supply to Yuen Long, Tin Shui Wai and part of Tuen Mun concurrently. CLP Power is deeply concerned about the incident and immediately set up an investigation panel comprising experts in power, civil, and fire engineering to find out what triggered the fire and make recommendations.
In the past weeks, CLP Power has been cooperating with relevant Government departments in their investigations, including having a joint inspection on 26 June with them to collect evidence and following up on the incident in accordance with the Electricity Ordinance. A preliminary report and a further report were submitted to the Government 3 days and 14 days after the incident respectively. The Investigation Panel submitted a final report to the Electrical and Mechanical Services Department on 22 August 2022, and the Government agrees in principle with the cause of fire and improvement proposals in the report.
CLP Power Managing Director Mr T K Chiang said, “CLP Power attaches great importance to all the recommendations put forward in the report. They will be followed through earnestly and thoroughly to prevent a recurrence of similar incidents in future and ensure a safe and reliable electricity supply. We would also like to thank relevant Government departments and community leaders for their assistance andvaluable advice, as well as technical teams and contractors for their tremendous efforts.”
“We appreciate the serious inconvenience caused to many citizens during the evening peak hours on a hot summer night and the disappointment it meant for our customers. We would like to sincerely apologise to the affected citizens and customers. We believe that there are important lessons we can learn for the future.”
At around 7:10pm on 21 June 2022, a CLP Power cable bridge spanning the nullah between Wang Lok Street and Kwong Yip Street in Yuen Long caught fire, affecting power supply to around 175,000 customers in Yuen Long, Tin Shui Wai and part of Tuen Mun. After tremendous efforts by our engineering staff in re-arranging emergency supply, CLP Power restored the power supply to some 90% of the affected customers around 7 hours after the incident, and the remaining 20,000 customers were notified that their supply was restored at around 8:00am on the next morning after the incident.
After the cable bridge caught fire, all cables inside the bridge were damaged. The engineering teams worked around the clock and made every effort to carry out new cable laying work. The 3 sets of 132kV high-voltage replacement cables were laid and energised within a week, fully restoring the power supply reliability of the grid in the affected districts. The damaged bridge was dismantled and removed.
Cause of the Fire
The intense fire which caused the bridge to collapse and seriously damaged the equipment inside the bridge made it very challenging to find out the actual cause of the fire.
According to laboratory test results and analyses conducted by the investigation panel, it has been confirmed that the fire was not caused by foul play. Neither power loading, the electrical protection system, hot weather nor high-voltage cables was a cause.
The fire expert considered that this fire incident was extremely rare. It is highly possible that a fluorescent light installed below the cross beam within a section approximately four metres from the junction between the steel bridge and the concrete chamber at Kwong Yip Street caught fire and ignited the nearest pilot cable below, with the fire spreading to the adjacent pilot and power cables. The fire then continued to spread from the Kwong Yip Street end to the Wang Lok Street end.
Power Grid Design and Power Restoration Challenge
According to the planning and design of the power grid, there are 3 sources supplying power to Yuen Long and Tin Shui Wai. They include the main source in the cable bridge and two other backup sources. As one of the backup sources had earlier been damaged, CLP Power had to make full use of the remaining backup source to supply power to affected customers.
The supply restoration process was full of challenges. Since the fire also damaged the communication cables inside the cable bridge, this affected the ability of System Control Centre to monitor the real-time status of the power systems in the affected area, making it difficult to immediately arrange other backup supplies through remote control. CLP Power urgently deployed 150 technical staff to different locations in the affected area to conduct load assessment and manual switching to facilitate the stepby-step re-arrangement of power supply to ensure that the backup supply was safe and reliable. In the process, priority was given to restoring essential services, including hospitals and railways.
Design of the Cable Bridge
The cable bridge located at Wang Lok Street in Yuen Long was commissioned in 1992. Its design complied with the relevant statutory requirements. It was constructed to support the development of Yuen Long and increase in electricity demand. Regular inspections and maintenance have been conducted after its commission. All the power and communication cables in the bridge operated normally before the fire broke out.
Risk Reduction Measures
To alleviate public concerns, CLP Power inspected the condition and equipment of 4 other cable bridges immediately and has completed a series of additional risk reduction measures to enhance the fire protection measures in these cable bridges. These measures include painting the cables with an appropriate fire-retardant coating, installation of heat detection systems and a wet-type fire suppression system, and replacing all fluorescent lights in the cable bridges.
The final report has recommended improvement measures in five areas, including management of low voltage installations, further enhancement of fire safety and security measures, emergency preparedness and communication, data communication enhancements within the power system and facility management. CLP Power will diligently follow through the recommendations made by the Panel.
1) Management of low voltage installations: Review the lifespan and maintenance of low voltage installations in common cable route infrastructure and establish an appropriate refurbishment / replacement programme.
2) Further enhancement of fire safety and security measures: Review the risk and reliability of the current high-voltage transmission circuits running through common cable route infrastructure, as well as the effectiveness and feasibility of the measures concerning security, fire protection and cable diversion. A fire hazard hunt on CLP operational facilities using a risk / probability matrix is also recommended.
3) Emergency preparedness and communication: Review emergency preparedness of key facilities coupled with joint exercises with the emergency services departments, and review the supply restoration process and stakeholders’ communication for major supply interruptions.
4) Data communication enhancements within the power system: Increase redundancy in communication cables along different routes to enhance the reliability of our remote-control capability.
5) Facility management: Good housekeeping with a focus on ensuring that excess materials used on site are stored properly.
To show care and express gratitude for the affected customers’ understanding, CLP Power will allocate HK$20 million to offer each affected residential customer Appreciation Vouchers worth HK$100 that can be used at the around 600 participating merchants in the three districts. The initiative also aims to boost economic activities in Yuen Long, Tin Shui Wai and Tuen Mun, bringing benefits to local businesses. The vouchers will be dispatched from mid-September.
About CLP Power Hong Kong Limited
CLP Power Hong Kong Limited (“CLP Power”) is the Hong Kong utility subsidiary wholly owned by CLP Holdings Limited, a company listed on the Hong Kong Stock Exchange and one of the largest investor-owned power businesses in Asia. CLP Power operates a vertically integrated electricity supply business in Hong Kong, and provides a highly reliable supply of electricity and excellent customer services to more than six million people in its supply area.
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