Which type of fire is not adequately dealt with by portable fire extinguishers?

Portable fire extinguishers are designed for tackling smaller fires that can be contained quickly and safely. They are effective for class A fires (ordinary combustibles), class B fires (flammable liquids), and class C fires (electrical). However, when it comes to large or spreading fires, portable extinguishers are generally insufficient.

The capacity of a portable extinguisher is limited; it usually contains a small amount of extinguishing agent, which may not be enough to effectively combat a large fire. A large or spreading fire poses several challenges, such as the rapid escalation of flames, the potential for structural collapse, and the difficulty in targeting the fire effectively with a portable extinguisher. Therefore, using these extinguishers on extensive fires can be dangerous and ineffective. In contrast to smaller fires, where a quick application might be effective, large fires require more comprehensive firefighting resources and strategies, such as fire trucks and trained personnel, to manage effectively.