In which scenario is it not advisable to use a fire extinguisher?

Using a fire extinguisher is not advisable when the fire is large or spreading rapidly because such situations often exceed the effectiveness of portable extinguishers. A small, contained fire can generally be managed with an extinguisher, especially if the person operating it has been properly trained. In an open area, there's typically less risk of the fire spreading uncontrollably, making extinguishers a potentially viable option. When an individual has received training on how to use an extinguisher, they are better equipped to handle smaller, contained situations effectively. In contrast, large or rapidly spreading fires pose severe risks not only to the user’s safety but also to those around them, as they may require more substantial firefighting resources than a portable extinguisher can provide. Therefore, in such cases, prioritizing personal safety and evacuating the area while calling for professional help is essential.