Hong Kong MTR blames insulation failure and wear for Lam Tin station incidents
MTR Corporation told the Legislative Council that two incidents at Lam Tin station on 13 and 14 October were caused by failed insulation and wear at a ground busbar connection. The first involved a short circuit from an unexpected conductive path; the second saw overheating after a portable earthing
MTR Corporation has told Hong Kong's Legislative Council that two incidents at Lam Tin station on the afternoon of 13 October and the morning of 14 October were caused by failed insulation and wear at the connection point of a ground busbar, according to a document submitted by the rail operator.
In its submission, MTR said a preliminary investigation into the 13 October incident, in which track equipment caught fire, found that a piece of insulation between switch point components near Lam Tin station had failed. This created an unintended conductive path between the train traction return circuit and the station's earthing system, causing a short circuit that produced a high current, sparks and fire.
Regarding the 14 October incident, MTR said its initial investigation found that a portable earthing switch in the affected electrical room had remained closed as a safety measure following the previous day's incident. As a result, electrical current did not travel entirely through its intended path to the earthing grid but instead flowed through other earthing routes. The sustained higher current caused related cable earthing components to overheat and emit smoke.