Half of Peninsular Malaysia was without power for several hours today causing massive traffic jams in major cities and leaving thousands of commuters stuck in trains.

Electricity went out at 12.15pm in the central and southern power grids affecting Klang Valley, Putrajaya, Seremban, Malacca and Johor Baru. However, power came back at 1.25pm in some areas.

During the blackout, Light Rail Transit personnel in all LRT stations evacuated passengers before completely shutting down the stations. According to Putra LRT, its train services were resumed at 4.45pm.

Meanwhile, KTM's inter-city train services were disrupted for almost three hours, bringing a total of 24 trains to a standstill. Normal services resumed at 3pm and no passengers have been reported to be injured.

The Express Rail Link to the Kuala Lumpur International Airport was also hit by the power failure but services have since resumed.

However, the airport, major ports, stock exchange Bursa Malaysia and hospitals were not affected as they have their own power back-up systems.

National news agency Bernama also reported that a number of people were trapped in lifts around Kuala Lumpur including in government and private sector offices.

Caught by surprise

The sudden power failure caught many by surprise and a lack of any clear information resulted in both land and mobile phone lines being clogged.

National power utility Tenaga Nasional Berhad's breakdown centre, when contacted, said that the power supply to all affected areas would be back by 4.30pm. They did not identify the cause of the blackout.

Areas in the north of the peninsular, including Ipoh and Penang, were however unaffected by the power outage.

The last time a power outage of this magnitude occurred was in Aug 3, 1996 when the entire Peninsular Malaysia was crippled by grid failure. The 14-hour blackout caused billions in losses.

Two years ago, power failure also hit five northern states resulting in between RM20 million and RM30 million in losses.

In September 1992, nine out of 13 states were without power for up to two days as Tenaga was unable to meet a surge in demand. Since then, a number of independent power producers were enlisted to help supplement demand for electricity.

Tripping at station

At a media conference held later in the afternoon, TNB deputy chief executive officer Abdul Hadi Mohd Deros told reporters that power supply had been restored to all affected areas as at 2.50pm.

However, a check by malaysiakini revealed that some residential areas in Subang Jaya and Bandar Sunway - both in Selangor - have yet to have supply restored as at 4.20pm.

Complainants told malaysiakini that they have checked their individual power fuse boxes to ensure it was switched on.

Hadi had earlier said that the interruption began at 12.16pm and was restored over two and a half hours later.

"The power outage was due to a tripping at the Sultan Salahuddin Abdul Aziz station in Kapar, Selangor. The station's operational busbar (power conduit of an electrical power plant) as well as the standby busbar failed," he added.

"There was a shortage of 1700 megawatts of electricity resulting in low voltage and frequency. We had to conduct a load shedding operation for the southern region".

Hadi promised the public that a thorough investigation would be conducted into the incident but could not reveal the exact cause of the tripping.

The same busbar - the starting point of the electric transmission system - is being used now, he added.

Compensation

The Tenaga deputy CEO refused to comment on how much losses TNB may have incurred from the disruption. Hadi had restricted himself to answering "technical questions" only.

He also refused to say if TNB will be paying out compensations to companies, industries or individuals who may have incurred losses from the mishap.

However, he said that there will be another press conference held in KLIA tonight at 11.30pm on the return of TNB CEO Che Khalib Mohamad Noh from China.

"What happened was of national importance and the prime minster as well as the energy, water and communication minister have been briefed," said Hadi, who answered a phone call from the deputy prime minister during the press conference.

Asked why the public were not being told the reasons for the power outage, he said TNB was not hiding any information and merely wanted to conduct a detailed check before revealing more information.

"We tried to get to the national radio stations to air reports (during the blackout) but the phone lines and air-waves were congested," he added.

A "third party" will be engaged - just like it was after the 1996 nationwide blackout - to improve the current system and to ensure a repeat will not occur, Hadi added.