Which fire stage does not contain an active fire but shows signs of combustion?

The incipient stage is the earliest phase of a fire's development. During this stage, combustion is just beginning, and while there may be signs of fire, such as smoke or heat, there is not yet an active flame. The materials in this stage are starting to reach their ignition temperature, which means they are undergoing a chemical reaction that could lead to a fire if conditions allow.

This stage is critical because it is when the fire is most manageable and can often be extinguished with minimal intervention. Understanding this stage helps firefighters and safety personnel identify the potential for fire development before it escalates into a fully active state.

In contrast, the growth stage involves an increase in flame production as the fire spreads, the decay stage represents a reduction in fire activity as fuel sources are consumed, and the fully developed stage is characterized by a sustained, active fire that is consuming a large amount of fuel. Thus, these stages are associated with visible flames and more significant fire activity, differentiating them distinctly from the incipient stage where combustion signs may be present but not fully developed into an active fire.