Endeavour Energy says it has on Wednesday restored power supply to more than 11,000 customers affected by the South Coast bushfires.

This includes getting power back to community facilities such as Milton Hospital, the Ulladulla Civic Centre and local sewerage treatment plants.

According to Endeavour Energy, approximately 7000 customers are without power in Sussex Inlet and many of the isolated communities dotted along the South Coast.

They are advising that where possible, people currently without power from bushfires should consider making alternative accommodation arrangements until their supply is restored.

Aerial and ground patrols today identified extensive damage to the electricity network where at least 45 power poles have been destroyed and need to be replaced.

Due to active fires still burning, there are still extensive parts of the network yet to be patrolled which may reveal further damage to powerlines.

"Endeavour Energy's immediate priority is to support the broader recovery effort of the Rural Fire Service and other emergency services to keep people safe and return some semblance of normality to bushfire ravaged communities," a statement said.

"This includes restoring power supply, helping to recover the telecommunications network and making available fuel to support emergency services operations and assist holidaymakers leaving bushfire affected areas.

"To offer affected customers some relief, Endeavour Energy is currently scoping the deployment of generators to supply customers where repairs to the network will take some time. The supply of generators, however, will not be feasible for all customers due to the level of damage or ongoing fires in the area."

On Thursday, Endeavour Energy crews from Western Sydney, the Southern Highlands, Wollongong and Shellharbour will assist local crews at Nowra and Ulladulla with repairs to bushfire damage and the restoration of power to customers on the South Coast.

"Assuming there is no further damage from active bushfires, Endeavour Energy's plan to have power restored to the vast majority of customers on the South Coast by late Saturday, January 4," the statement said.

Earlier:

Power will be out to parts of the South Coast for at least another 24 hours and up to a week in some places, Endeavour Energy has said.

Power has been down since yesterday for a 180km stretch of coast from South Nowra to Moruya. In many cases, with the power goes phone and internet communication.

With the Rural Fire Service giving permission for aerial scoping to start today, Endeavour will soon be able to assess how much damage there is to the network of poles and wires.

Some would need to be rebuilt "from the ground up", Endeavour spokeswoman Janine Cullen told ABC Radio.

She said power would likely be out in fire-hit areas for at least 24 hours, and possibly for as long as a week in the worst-hit areas.

Ms Cullen said Endeavour's first priority was clearing fallen power poles and transmission lines from the Princes Hwy, to enable deliveries of essential supplies and evacuations where necessary.

Police have estimated the power outages are affecting 46,000 people but this could be more given the number of holidaymakers in the area.

There is no timeframe for when the Princes Highway would be able to be re-opened. It is likely to remain closed from Milton to Falls Creek for at least today.

Shoalhaven Mayor Amanda Findley said the power outage had caused some sewage overflows but these were receding now generators were in place.

People were still advised not to swim between Sussex Inlet and Lake Tabourie after the overflows.