West Sussex firefighters will be among those taking part in an eight day period of strike action in August.
The further industrial action will take place due to the government failing to improve their pension proposals, the Fire Brigades Union (FBU) claimed.
It will take place from Saturday August 9 to Saturday August 16 between 12pm and 2pm and 11pm to 12am.
Matt Wrack, FBU general secretary, said: “It is absolutely ludicrous that a government can impose a scheme which means that firefighters will have to ride engines and rescue people from fires up to age 60.
“This is unsafe and unrealistic for both firefighters and the public.
“We know it, and the public know it, but the government will not listen to the evidence based case we have made to them.”
The FBU said proposals incorporating flexible retirement options should be included in an improved offer for its members to consider.
Sean Starbuck, FBU national officer, says: “It’s extremely disappointing that we have had to issue more strike dates but the government are simply not listening to our concerns.
“We have a new fire minister but to date she doesn’t appear to have listened to our case.
“The government still has an opportunity to improve their offer which could avoid the need for action.”
No industrial action is being taken in Scotland and Northern Ireland as improved pension proposals are being discussed.
Mr Starbuck added: “Firefighters are angry as the Westminster government claims we don’t want to resolve this dispute.
“This is absurd as the situation both in Scotland and N Ireland shows this is simply not the case.”