NCCER Mobile Crane Practice Exam

A signal person is required when crane operations take place within the boom's length of power lines because the proximity to power lines presents a significant risk of electrocution or electrical hazards. The National Institute for Occupational Safety and Health (NIOSH) and Occupational Safety and Health Administration (OSHA) guidelines mandate that when cranes operate near power lines, a trained signal person is necessary to help ensure that the crane does not come too close to these energized lines. This is crucial to maintaining safety for operators and crew, as they may not always be able to see the lines or accurately judge distances when the crane is in motion.

In contrast, the other scenarios do not inherently require a signal person under established safety protocols. Conditions such as gusting winds, load capacity percentages, or high-voltage specifics might increase risk but do not directly necessitate a signal person like proximity to power lines does. Hence, the requirement for a signal person stems specifically from the hazards related to working near power lines, emphasizing safety first in such operations.