The matter was heard in the commission on Monday.

Essential Energy acting chief executive officer Gary Humphreys said the decision means ETU members are required to be available for work duties as normal.

The energy supplier successfully argued that the proposed work stoppages would threaten public safety and network reliability.

The six hour hearing was heard before Senior Deputy President Hamberger in the Fair Work Commission.

"Essential Energy will always put the safety of our employees, contractors and the public above anything else so we are pleased that the Fair Work Commission has shut down the protected industrial action proposed by the ETU," Mr Humphreys said.

But ETU secretary Steve Butler said Mr Humphreys was perfectly content to sack 800 workers - many of them from the Port Macquarie area.

"He is concerned about one job and one job only and that is his," Mr Butler said.

"We have been arguing with the organisation for over 12 months about what this new enterprise agreement will look like.

"And for them to do something on the last day ... their statements about looking after the public are rubbish."

The Fair Work Commission now requires both parties to enter a 21 day bargaining period.

The matter will return to the commission for arbitration after that time frame if no agreement is reached.

The ETU had also issued notices proposing a further 30 day protected industrial action period in June.

Essential Energy has been in negotiations with unions since April 2015 for a replacement Enterprise Agreement that meets the needs of employees, safeguards safety performance, is modern and flexible, contains costs to customers, and supports the business' objectives of running a safe, reliable, affordable network.

"Essential Energy will now consider the implications and most appropriate next steps in these long-running negotiations," Mr Humphreys said.

Mr Butler said the energy supplier's claims that the new agreement was necessary to help reduce power bills is unfounded.

"Our information is that electricity bills in Port Macquarie will not come down," he said.

"These savings go to the retailer and the retailer does not reduce the price of electricity."

peter.daniels@fairfaxmedia.com.au