Blame a simple water leak for July 7’s massive MRT breakdown

It led to systemwide power tripping.

If you were among the thousands of commuters who arrived home late when MRT services broke down on July 7, then you have a water leak to blame for stealing your dinner.

A joint release by SMRT and the Land Transport Authority said that water was found to be dripping onto the third rail cover near an insulator in the stretch of tunnel between Tanjong Pagar and Raffles Place.

Test results on the sample residue from the third rail cover, and on water collected from the tunnel leak, found mineral deposits with high chloride content.

The insulator's weak resistance allowed electricity to flow through the insulator to the ground, which resulted in the activation of the 64P safety mechanism at multiple locations in the network.

The activation of the 64P safety mechanism is what tripped the power system.

"To better monitor the condition of the insulators, SMRT will be installing data loggers at all 47 traction power substations on the NSEWL within the next two months. The 64P setting will also be raised from the current 136V to 200V which will make the network less susceptible to such power trips. The 200V setting is in line with international standards, and the setting on our newer MRT lines like the Circle and Downtown Lines. Commuter safety is not compromised," the statement said.