In which situation is using a fall arrest system mandatory?

Using a fall arrest system is mandatory when working from a scaffold that is 10 feet high because regulations and safety standards dictate that any work performed at heights of six feet or more in the construction industry requires specific safety measures to protect workers from fall hazards. Scaffolding poses a significant risk of falls due to the elevated work surface, and the use of a fall arrest system, which may include harnesses, lanyards, and anchor points, ensures that workers have a safety mechanism in place should they lose their footing or experience a mishap. This requirement is aligned with guidelines set forth by agencies such as OSHA, reinforcing the importance of safety gear in elevated work environments to prevent serious injury or fatality from falls.

The other situations listed do not inherently involve fall risks that necessitate the use of a fall arrest system according to common safety protocols. Working in a confined space, maintaining equipment, or being near open flames emphasizes different safety precautions, such as ventilation or fire safety measures.