North East Line & Sengkang-Punggol LRT Power Fault (Aug 2025)

On Tuesday, 12 August 2025, a power fault caused a significant disruption to train services along the North East Line (NEL) and the entire Sengkang–Punggol Light Rail Transit (SPLRT) network. Train services stalled for three hours, and blackouts were reported across many stations.

No train service was available on the NEL between NE8 Farrer Park – NE18 Punggol Coast and the entire SPLRT system, affecting the journeys of northeast commuters who had few alternative train lines or bus routes. This is one of the longest train disruptions in 2025.

On Friday, 15 August 2025, yet another power fault caused a four-hour outage of the entire SPLRT network. The incidents on both days necessitated the detrainment of passengers from trains that had stalled between stations.

12 Aug – Cause & Recovery

The power fault was traced to a power trip at the Sengkang Rail Depot substation, which supports both NEL and SPLRT. Based on SBS Transit’s preliminary investigations, a failure of the power switchboard caused a flashover in one of the voltage transformers used to regulate the power supply. This resulted in a trip in both the main and backup power supplies as part of the power protection mechanism.

The faulty voltage transformer could not be repaired immediately, and a decision was made to bypass the depot substation and draw power from another substation at Dhoby Ghaut so that train services could resume. SBS Transit engineers also carried out extensive checks to ensure that the fault would not impact operational stations. Power was progressively restored to the affected stations, and NEL service fully resumed at 2:10 PM.

The power fault also disrupted services on the entire Sengkang-Punggol LRT. Recovery works for the SPLRT had to be carried out in stages to ensure a steady increase in the electrical load and prevent another power trip, as both NEL and SPLRT are now relying on a shared substation.

To ensure the safe operation of SPLRT services, a complete restart and checks of the signalling, power systems, and LRT vehicles had to be carried out. This took additional time, and power to the Sengkang LRT was restored at 3:34 pm, while service on the Punggol LRT resumed at 4:04 pm. However, to avoid stressing the power supply from the single substation, a decision was made to operate SPLRT services on a single track for both the East and West loops during the evening peak periods.

During engineering hours on the night of 12 August 2025, SBS Transit engineers worked with LTA engineers to restore power supply to the NEL depot substation.

15 Aug – Cause & Recovery

The power fault on 15 August occurred at around 8.40 am, disrupting services across the entire Sengkang-Punggol LRT network for over two hours.

Preliminary findings by SBS Transit identified a cable fault between two stations that tripped the LRT network. Following the earlier incident on 12 August 2025, which damaged the backup switchboard of the power system, the LRT network had been operating from power supplied via the main and single switchboard. Without the availability of the backup switchboard, this cable fault caused a long service disruption and increased service recovery time.

The power fault also resulted in 10 trains stalling on the tracks, all of which required passengers to be detrained. Services were recovered since 11.05 am for the Sengkang LRT and at 11.20 am for the Punggol LRT.

In the afternoon from 3.15 pm to 5.00 pm, Sengkang LRT services were reduced to single-direction operations on both the East and West Loops to facilitate cable inspections, such that repairs could be undertaken more efficiently during engineering hours. On the West loop, only the Outer loop was operated (Sengkang towards Renjong), while on the East loop, only the Inner loop was operated (Sengkang towards Ranggung). Full services resumed at 5.15 pm.

Rail Bridging Services

Free regular bus services and bridging bus services were made available at all affected stations during the disruption.

Preliminary Findings (16 Aug)

In a joint statement on August 16, LTA and SBS Transit provided an update on the investigations into the power fault incidents along the NEL and SPLRT on Aug 12 and Aug 15.

12 August 2025 Incident

The incident involved a fault within the 22 kV power supply system located at the Sengkang Depot Substation, which supplies power to the NEL and SPLRT. The 22 kV power supply system has two interconnected switchboards (see diagram), which serve as backups for each other.

On 12 August, two faults were encountered at the voltage transformer for Switchboard 2. The first involved a high current surge due to a fault in the voltage transformer. The second was a dislodged cable connecting to the voltage transformer.

In a normal situation, the first fault would have triggered the fuse in the voltage transformer, cutting off the electric current. However, on the incident date, the dislodged cable came into contact with the metallic surface of the voltage transformer panel, allowing electric current to continue flowing, despite the fuse having blown. The high current surge damaged Switchboard 2. As the two switchboards were connected, the high current surge from the fault caused Switchboard 1 to disconnect from the system to avoid damage. With Switchboard 2 damaged and Switchboard 1 disconnected, the power supply to parts of the NEL and the SPLRT was cut off. LTA and SBS Transit claim the above “double fault” scenario is rare, and they are working to eliminate a recurrence in the future.

The NEL and SPLRT services were progressively restored on the same day using a backup power supply. Due to the extensive damage, Switchboard 2 could not be repaired immediately. As Switchboard 1 was protected from damage, it was reconnected to allow normal service to resume the next morning.

LTA and SBST worked together with their contractors to ensure that repairs to the voltage transformer and Switchboard 2 were carried out expeditiously and safely. These were completed on 16 August.

15 August 2025 Incident

On 15 August, a power cable fault occurred between Farmway and Kupang stations on the Sengkang LRT. In normal circumstances, Switchboard 2 at Sengkang Depot Substation could have been used to provide backup power, but since it was still out of service from the incident on 12 August, the power cable fault caused the entire network to lose power. Service progressively resumed during the afternoon after power was restored. Some time was required as we had to complete the safe detraining of all passengers first.

LTA and SBST are still investigating the cause of the cable fault. Engineers from LTA and SBST are also testing the cables along the entire SPLRT network to assess their condition. These tests on around 28km of cables is expected to be completed by 23 August, as they can only be carried out during engineering hours.

Future

As part of the Sengkang Depot expansion works, LTA will be implementing a secondary power supply source directly from the SP Power Grid, which will be completed by 4Q2025.

Sequence of Events (12 Aug):

Summarised from SBS Transit’s X (formerly Twitter) account posts:

Sequence of Events (15 Aug):

References

• Train Services Resumed on North East Line and Sengkang-Punggol LRT – SBS Transit
• SBS Transit X (Formerly Twitter)