Ausgrid has confirmed that a 132,000 volt underground power line was struck by a contractor who was working on a new stormwater drain, curbs and guttering on Pittwater Road in East Ryde at about 3pm on Thursday, cutting power to parts of Ryde, West Ryde, Meadowbank, Eastwood, Putney, Denistone and Rhodes.

The energy supplier will meet with Ryde council on Monday as part of an investigation that has been launched into the accident that caused a loss of power to thousands of families, Ryde Hospital and 20 sets of traffic lights across six suburbs, leading to peak hour traffic chaos and inconvenience to commuters, residents and businesses in the area.

"There will be a formal investigation to establish the exact circumstances of the cable strike," an Ausgrid spokesperson told Fairfax Media. "This is a major power line that feeds Meadowbank zone substation."

City of Ryde staff remained at the site until power had been fully restored, said a council spokesperson, who confirmed that the construction team had followed Ausgrid's "dial before you dig" guidelines before carrying out the work.

"In preparation for these works, Ausgrid together with the appointed contractor had several on-site visits in confirming the location of the high voltage cables prior to excavations commencing on the site. Confirmation was also made with the Dial a Dig service in confirming the location of the cables."

Given any contact with the major power line is "extremely dangerous", Ausgrid added it was "very fortunate to not have any injuries on this site. It could have easily been a different story."

"We need to make sure we can learn from what's gone wrong and work with the parties involved to take steps to prevent it from happening again. All underground work must be done very carefully, there is enormous risk to safety, to workers, to the public and also to the supplier," they said.

Residents in the area have reported concerns over spoiled frozen food and at least one has reported a minor injury from losing footing on a dark pavement.

"If there are customers who want to contact us about compensation, they are welcome to call our claims line," said Ausgrid. "We understand it was very inconvenient timing for people who work, live and travel in this area."