Which of the following is a critical safety measure regarding crane operations near power lines?

The critical safety measure concerning crane operations near power lines is to never assume power lines are safe to contact. This principle is essential because overhead power lines carry high voltage electricity, which can pose a severe risk of electrocution or injury if approached too closely. Operators must maintain a high level of caution and awareness around power lines and understand that even electrical insulation or nearby clearance can be deceptive.

This rule emphasizes the importance of a proactive approach to safety by requiring operators to remain vigilant and follow established guidelines regarding distances and precautions. By adhering to this safety measure, workers can effectively prevent accidents and ensure a safer working environment. The other options, while related to power line safety, do not capture the fundamental principle of cautious awareness and the necessity of assuming potential risk at all times when working near electrical power sources.