In which situation is a safety harness and belt mandatory?

A safety harness and belt are mandatory when on scaffolding or elevated surfaces because these environments present significant fall hazards. Scaffolding allows workers to perform tasks at heights that exceed typical floor levels, often several stories above the ground, where the risk of falling is heightened. The use of safety harnesses and belts is critical in preventing serious injuries or fatalities resulting from falls.

In contrast, while working near electrical lines, transporting heavy loads, or operating machinery can be hazardous in their own right, they do not inherently require a safety harness and belt in the same way that working at elevation does. Each of those situations has its own safety measures and requirements, but the immediate need for personal fall protection is most relevant in the context of scaffolding or elevated surfaces.