But a law firm says it will consider launching a class-action lawsuit if it emerges the government-owned company neglected its duties.

Essential Energy believes trees fell onto powerlines during extreme weather conditions, sparking the blaze that destroyed about 100 properties on Sunday.

A preliminary investigation by the Rural Fire Service found electrical infrastructure was the likely cause of the fire.

The Electrical Trades Union subsequently said the NSW government and Australian Energy Regulator had serious questions to answer over "massive maintenance funding cuts".

It will ask both the NSW Coroner and Mick Keelty, who is leading an independent investigation into the blaze, to consider if the regulator played a role in power companies cutting back on maintenance.

"Tathra is potentially the latest example in a long list of fires caused by cuts to maintenance by power network," assistant secretary Justin Page said in a statement on Friday.

But Essential Energy chief executive John Cleland said an initial review showed inspections and maintenance of the area around Reedy Swamp Road, just east of Bega, were "up to date and in accordance with prescribed standards".

"Preliminary internal enquiries indicate network protection equipment activated as it is designed," he said in a statement.

Law firm Slater and Gordon is investigating whether the blaze could have been prevented.

"We will be looking at whether Essential Energy adhered to stringent inspection and ongoing maintenance requirements and ultimately what could have been done to prevent this bushfire," lawyer Rory Walsh said in a statement.

The firm will closely watch a coronial inquest to determine the cause of the fire and an independent inquiry into the emergency response.

It will also hold community meetings with affected residents and property owners.

"This type of litigation tends to be fiercely contested by electrical infrastructure providers, but we have extensive experience and are well equipped to take on this legal battle for Tathra," Mr Walsh said.

Essential Energy's "preliminary understanding" is that trees fell onto powerlines during extreme weather conditions but no conclusive finding has been made.

Power was restored to all customers in Tathra on Thursday night, four days after the fire tore through the south coast town.

Recovery co-ordinator Euan Ferguson has warned it could take 12 to 18 months before some displaced residents can return home.

A recovery centre has opened at the Bega Civic Centre to help victims with a range of services including disaster welfare, insurance, providing access to counsellors, shire planning and legal aid.

In total 65 homes were destroyed along with 35 cabins and caravans.

Australian Associated Press