The Land Transport Authority (LTA) and SBS Transit are undertaking comprehensive investigations and system tests after a rare “double fault” disrupted rail services on the North-East Line (NEL) and the Sengkang-Punggol Light Rail Transit (LRT).
In a joint statement issued on 16 August 2025, the two agencies confirmed that both incidents—on 12 August and 15 August—stemmed from electrical faults affecting the Sengkang Depot Substation, leading to major service disruptions.
The first incident on Tuesday, 12 August, caused a near three-hour service halt on the NEL and a five-hour disruption on the Sengkang-Punggol LRT. A second incident on Friday, 15 August, resulted in another four-hour disruption to the LRT network.
Repairs to the damaged substation equipment were completed by Saturday, 16 August, while investigations into the root causes continue.
Double fault explained
The Sengkang Depot Substation features two interconnected switchboards designed to back each other up in case of faults. However, both systems were compromised during the 12 August incident.
The sequence began with a fault in the voltage transformer for Switchboard 2, resulting in a high current surge. This should have triggered the fuse, cutting power flow. However, a dislodged cable made contact with a metallic surface on the transformer panel, allowing current to continue despite the fuse being blown.
This rare and unexpected scenario damaged Switchboard 2.
Because the two switchboards are connected, the surge prompted Switchboard 1 to disconnect automatically to protect itself. With Switchboard 2 damaged and Switchboard 1 offline, power was cut to parts of the NEL and Sengkang-Punggol LRT.
Services were progressively restored later on 12 August using a backup supply, though Switchboard 2 remained inoperative due to the extent of the damage.
By the following morning, Switchboard 1 was safely reconnected, allowing full service to resume.
Cable fault worsens situation
On 15 August, just days after the initial incident, a separate power cable fault occurred between Farmway and Kupang stations on the Sengkang LRT.
This incident resulted in a network-wide power loss. Since Switchboard 2 was still under repair, there was no secondary backup available.
Power was restored later that afternoon, and LRT services resumed progressively.
LTA and SBS Transit confirmed that they are still investigating the cable fault and assessing its implications for the broader power system.
Network-wide testing underway
To prevent recurrence, engineers are currently testing all cables along the Sengkang-Punggol LRT system, covering approximately 28km of track.
These tests are being conducted during engineering hours and are expected to conclude by 23 August.
The agencies reiterated that the scenario involving simultaneous transformer fault and cable displacement is “rare”, but measures are being taken to eliminate the risk of recurrence.
Longer-term system upgrades
In response to the vulnerabilities exposed, LTA announced it would implement a secondary power supply connection directly from the SP Power Grid. This system is expected to be completed in the fourth quarter of 2025 as part of ongoing Sengkang Depot expansion works.
Additionally, LTA is working with SBS Transit on a broader upgrade of the power supply infrastructure for both the NEL and the Sengkang-Punggol LRT.
These efforts are aimed at enhancing system resilience and ensuring backup systems remain robust under a variety of fault conditions.
LTA and SBS Transit concluded their statement by affirming their commitment to passenger safety and minimising service disruption across Singapore’s rail network.
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