SINGAPORE - A small tear in the insulation of a live wire inside the lamp post that touched its metal casing is the probable cause of the electric shock that injured two teens on Sunday (June 13).

The tear would not be visible unless the junction box is removed, the Bishan Toa-Payoh Town Council said on Wednesday.

A junction box houses the connection between underground cables and cables within the lamp post, supplying power to the lamp.

The town council manages the estate where the incident happened, at the fitness corner near Block 63 Lorong 5 Toa Payoh.

The town council told The Straits Times that works were done to rectify the problem on Tuesday.

When ST visited the spot on Tuesday, a group of workers could be seen replacing all four lamp posts near the fitness corner with new ones. The four included the lamp post that injured the teens.

Responding to ST queries, the town council confirmed that similar issues were not observed in the other three lamp posts surrounding the fitness corner. But they were replaced as a preventive measure as the lamp posts run in a series under one circuit.

About the lamp post that caused the shock, it added: "The last check was carried out by a licensed electrical worker in January 2021, with no irregularities found."

ST reported on Tuesday that one of the teens, 14-year-old Muhammad Rifqy, remains hospitalised at KK Women's and Children's Hospital with electrical burns to his right hand and an elevated muscle enzyme count. The latter is an indicator of muscle injury, and can lead to heart and kidney problems.

The boy had held on to the lamp post while attempting to retrieve a football that had gone astray.

The town council said licensed electrical workers carry out six-monthly inspections to switch rooms and electrical installations to ensure that they are safe.

Its staff also inspect the exterior of outdoor fittings monthly to check for defects and promptly rectify them.

Responding to ST queries, Mr Chong Kee Hiong, an MP for Bishan-Toa Payoh GRC and the town council chairman, said the town council was saddened by the incident, and wished the boys a smooth and speedy recovery.

Mr Chong also said the town council had visited the families to offer them support and assistance. "We will continue to keep constant contact with the families," he said.

He added that the well-being and safety of residents are his top-most priorities as town council chairman.

"Following the incident, I had instructed (the town council) to immediately conduct a thorough check on the lamp posts within the same circuitry to ensure they are safe. This has since been completed."

He said the town council had started checks on all lamp posts in Bishan-Toa Payoh GRC and Marymount SMC.

"We take a serious view of this incident and will do our utmost to ensure that electrical installations in our town are safe and well-maintained," he said.

Electrical engineer Simon Lee said the junction box is a weatherproof box mounted on or adjacent to a lamp post, connecting underground cables to cables within the lamp post, thereby supplying power to the lamp.

In a picture provided to ST on Tuesday by Mr Muhammad Nazlan, father of Rifqy, a black wire could be seen dangling out of a white, round object near the foot of the lamp post that caused the shock.

Mr Lee, who is chairman of the mechanical and electrical engineering technical committee at The Institution of Engineers, Singapore, said the white, round object was likely the junction box, and the wire was possibly the live cable or earth cable.

"Usually, these cables do not hang outside the junction box, and are laid within the conduit connected to the junction box. In addition, the lamp post should be separately earthed internally."

He added that there would be no visual indication of whether live current was flowing through the metal casing of the lamp post.

"However, the cable supplying the lamp post with electric current should be protected by a circuit breaker. The circuit breaker can detect a fault current and automatically cut off the electrical supply if the current exceeds its preset threshold."

He also said routine inspections for electrical installations like lamp posts usually do not require the junction box to be removed for checks, only to see if the box is intact and not tampered with.

"The junction box, together with the cable termination, is normally opened and checked during the initial installation."

He added: "The small tear on the cable could be caused by incidental damage during installation work or external damage on the junction box.

"Natural deterioration is unlikely to cause physical tears on the cable."