Sydney: 50,000 premises without power as second cable fails

Parts of Sydney were without power again this morning, following the second cable failure in a week. Photo / Supplied

About 50,000 homes and businesses in parts of Sydney's CBD and the eastern suburbs are without power after a major cable failed.

The power outage, which occurred about 10.30am (12.30pm NZST), affected the northern part of the city centre, parts of the eastern and inner city suburbs, EnergyAustralia spokeswoman Kylie Yates told AAP.

Ms Yates said it was not the same cable which failed last Monday, throwing the city into chaos, but a second one.

"EnergyAustralia is working to reroute power to these areas to get the power back on as soon as possible," she said.

On initial reports, police believe about 50 sets of traffic lights are out of action.

There are four major power cables that supply two substations in central Sydney.

It is the second time this week that a major power cable has failed. The first is still out of action as it is being repaired.

Sydney's CBD was thrown into chaos on Monday when a massive peak-hour power outage forced the closure of major road links, blacked out traffic lights, and left dozens of people stranded in lifts.

The problem was caused by the failure of one of the four cables that supply two major substations in central Sydney.

About 70,000 homes and businesses, mostly in the city's north and surrounding suburbs were affected, plus inner eastern suburbs including Paddington, Rose Bay and Darlinghurst, were affected in that outage.

Some 140 sets of traffic lights were blacked out, with police directing traffic at 40 of them.

Power was restored within two hours, but not before the Roads and Traffic Authority (RTA) was forced to close two of the busiest roads out of the city - the Harbour Tunnel and Eastern Distributor - around 5.45pm (AEDT).

- AAP