South Yorkshire fire crews are accusing their managers of multiple breaches of health and safety legislation over what they say is the imposed introduction of small vans to replace fire engines.
The Fire Brigades Union has served a Safety Critical Notice warning them of their liability if a member of the public or a firefighter is injured or killed.
But the fire service says Small Incident Units have been in service for two years, with no reported accidents or near misses.
The units are commercial vans painted fire service red with blue lights and high-visibility stripes.
They have limited water capacity and are operated by a crew of three firefighters.
Firefighters are unhappy about plans to introduce a unit at Sheffield’s Elm Lane station in Sheffield Lane Top.
John Gilliver, FBU brigade secretary, said: “Fire professionals know every large fire starts as a small fire and we don’t always know what we will find when we arrive. Firefighters will be put at intolerable risk at incidents if they are deployed in these vans.
“If a small fire has spread to a building with people inside, then two or three firefighters are not enough to deal with that safely.
“Everything that makes you a firefighter will push you to enter the building, even with the greatly-heightened risk you will face.
“We face risks in the hostile environments in which we work, but we know how to limit the risks to us when there are enough personnel, equipment, proper procedures and training.
“These small fire units will not provide that.
“It places intolerable pressure on the officers in command at the scene and leaves them vulnerable if anything goes wrong.
“Firefighters have been killed in situations where there is a lack of personnel, equipment and training. This is all entirely foreseeable and the introduction of these vans is reckless and totally unacceptable.”
But a fire service spokesman said: “We are extremely disappointed the FBU will still not allow its members to carry out the necessary training for the Small Incidents Unit, which has passed a series of rigorous and independent safety examinations and has responded to more than 700 fires successfully since August 2009.
“We are keen to introduce the SIU to Elm Lane station in full accordance with the Fire Authority’s decision following a full public consultation.
“It will respond to small incidents in the Sheffield area, keeping rescue pumps free to attend life-risk incidents.
“We have always stated the SIU will not be mobilised to any type of premise fire or vehicle fire.
“We remain committed to the introduction of the SIU to enhance fire cover in the Sheffield area and strongly urge the FBU to allow its members to begin training for the vehicle.”