Fire Brigade Union (FBU) members in London are to vote on whether to call for industrial action "up to and including strikes" by 24 June.
The FBU's London Regional Committee has called on members to unite in a campaign against proposed reforms.
The reforms would put an end to current working hours which unions claim could endanger public safety.
London Fire Brigade said that the changes were designed to allow officers to make better use of their time.
In an interview with the Politics Show London, London Fire Brigade Commissioner Ron Dobson said: "We need to change the shift pattern in order to drive more efficiency.
"It's all about going out and educating the public to prevent fires happening in the first place.
"We need more time to be able to do that and the current nine-hour day shift and 15-hour night shift is a very inefficient way of working."
However the FBU, which represents more than 5,000 members, said the reforms could also result in stations being closed at night and a reduction in staff levels.
The Politics Show broadcasts at 1200 GMT on BBC One and for seven days after on the BBC iPlayer