Fires occur when a competent ignition source comes into contact with fuel. What additional condition must be met?

For a fire to occur, the ignition source must not only be in contact with the fuel but must also remain in contact long enough to raise the fuel's temperature to its ignition point. This is crucial because even if a competent ignition source is present, if it does not remain in contact with the fuel long enough, the fuel may not reach the necessary temperature to ignite.

This principle plays a critical role in fire dynamics and prevention strategies, as it highlights the importance of the duration of contact between the ignition source and the fuel. The other conditions, such as the presence of oxygen or the characteristics of the space, can enhance or affect the fire's development but are not strictly necessary for the ignition process itself to take place. Thus, the duration of contact is a fundamental factor in the ignition and subsequent development of a fire.