A crane operator is conducting a critical tandem lift involving two mobile cranes. According to industry best practices and CSA Z150, what is the minimum percentage of the critical lift capacity that should be allocated to each crane?

Question: A crane operator is conducting a critical tandem lift involving two mobile cranes. According to industry best practices and CSA Z150, what is the minimum percentage of the critical lift capacity that should be allocated to each crane?

Answer options:

• 50% of the total load.
• At least 75% of each crane's rated capacity at the determined radius. ✅ At least 60% of each crane's rated capacity at the determined radius.
• At least 85% of each crane's rated capacity for the shared portion.

Correct answer: At least 60% of each crane's rated capacity at the determined radius.

Explanation: CSA Z150 (Ch. 6.3.2.1) and industry best practices for tandem lifts generally recommend that each crane should not be loaded in excess of 75% to 80% of its rated capacity for the specific radius and configuration. However, for a critical lift where the load is shared, ensuring each crane handles at least 60% of its individual rated capacity for its portion provides a sufficient margin of safety for potential uneven load sharing or minor boom deflections.