Residents of one block in the 50-storey Pinnacle@Duxton in Tanjong Pagar were stranded yesterday, with some climbing as many as 20 flights of stairs, when their lifts failed to work for two sustained periods.

Account manager Aisyah A.R., 37, had to carry her four-year-old daughter down 19 flights of stairs at Block 1E to the 26th floor's skybridge, where she found a set of working lifts in a different block.

"My daughter thought it was an adventure, but I saw an elderly man in his 70s having to make his way down slowly with a cane."

Pinnacle@Duxton has seven blocks with six units on each floor. Each block is serviced by five lifts.

However, from about 9.10am to 10am, and from around 5.30pm to 7.15pm, residents at Block 1E were left without any lift access at all.

They had been told last Saturday there would be a power shutdown from 9am to 6pm yesterday to service the block's electric switchboards, but that there would be two lifts running during that time.

The Tanjong Pagar Town Council, which manages the estate, said the lift operations were affected as it took about 45 minutes to get the generator - an alternative power source for the lifts -running in the morning.

Similarly, in the evening, workers had to switch off the generator, reconnect the lifts to the block's power source, and ensure these were working. The test took about an hour, a spokesman said, during which residents had to wait.

The town council had been replacing Block 1E's air circuit breaker, which protects an electrical circuit from damage caused by excess current. Despite the component being less than 10 years old , it was in critical condition, which could cause power failure.

Most air circuit breakers last at least 15 to 20 years, several engineers told The Straits Times.

Some residents said other lifts had stopped working previously - Block 1D suffered the same fate about two months ago.

The spokesman confirmed this, and said both Block 1D's and 1E's failing circuit breakers were from L&T India. They have since been replaced with Mitsubishi ones.

"The newer model should be able to last for a minimum of 10 years," said the town council.

Retiree Ng Kim Leng, 65, who relies on a personal mobility device, was upset that he could not return to his home on the 33rd floor immediately after finishing a tiring dialysis session earlier in the evening.

"If the town council had given accurate information, I would have gone to my daughter's house instead of waiting here," he said.