Twin faults led to boy's fatal electrocution while showering
Faulty electrical installation and failed circuit breaker in Bukit Batok flat led to his death by electrocution
Faulty electrical installations done during a Housing Board upgrading programme led to the fatal electrocution of a 15-year-old boy who was showering, a coroner's inquiry has found.
Since the 2016 incident, HDB has advised contractors carrying out works for the Home Improvement Programme (HIP) to alert residents to any irregularities in water heater wiring .
Home owners have also been advised to test their circuit breakers monthly by pushing its test button and seeing if it trips.
In her report on the death of Tan Yao Bin, State Coroner Kamala Ponnampalam found that the electric shock that killed the boy was caused by a faulty switch socket outlet wired to a water heater and a faulty residual current circuit breaker (RCCB).
Yao Bin's mother, Madam Zhang Aiyan, had decided in 2015 to get a new water heater installed after renovation works at their Bukit Batok flat under the HIP were completed.
She asked a worker from JL Engineering Construction, the electrical sub-contractor for the project, to install the heater using the existing wiring and a three-pin plug.
The worker's supervisor, Mr Ooi Kah Heong, tested the wiring and the circuit breaker and found them to be in order.
However, three-pin plugs are not designed to support the current drawn by water heaters.
Neither Mr Ooi nor his worker are licensed electrical workers.
Coroner Kamala found that while Mr Ooi was aware that it was unsafe for a water heater to be wired to a three-pin plug, he did so as he thought his job was to "reinstate what was formerly in the toilet".
Mr Ooi testified that he would inform the owner of a unit undergoing HIP that a three-pin plug was unsafe for a water heater and offer to change it. But he said he did not have the chance to tell Tan's family.
During investigations, it was found that the plug's cable connection to the neutral and earth terminals were loose, and the neutral and earth cables had melted and fused together.
The earth cable was found to be connected to the casing of the heating tank, which was connected to the shower head by a metallic hose.
Said Coroner Kamala: "It is likely that the current flowing from the water heater in the neutral cable could have flowed into the earth cable due to the fusing of the two cables.
"As the cable connection to both the neutral and earth terminals were loose, the current could have flowed back to the heating tank of the water heater instead."
This, she added, would mean that the current would have completed its path by flowing into the tank's casing, through the metallic hose, and into Tan's body, then the wet floor.
At the same time, the circuit breaker did not trip.
An RCCB detects residual current which has been diverted from a circuit and breaks it should a significant residual current be detected.
The RCCB at the flat was later tested and found to be faulty.
Coroner Kamala found that the current flowing was enough to deliver a fatal electric shock.
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