An operator is securing a 15-tonne mini-excavator to a flat deck trailer using chain binders. The recommended WLL (Working Load Limit) for each chain is 6,670 kg (14,700 lb). How many chains are minimally required to secure this excavator according to CSA Standard Z150, assuming the chains are applied at an angle of 45 degrees or less to the deck and provide direct securement?

Question: An operator is securing a 15-tonne mini-excavator to a flat deck trailer using chain binders. The recommended WLL (Working Load Limit) for each chain is 6,670 kg (14,700 lb). How many chains are minimally required to secure this excavator according to CSA Standard Z150, assuming the chains are applied at an angle of 45 degrees or less to the deck and provide direct securement?

Answer options:

• 2 chains
• 3 chains ✅ 4 chains
• 5 chains

Correct answer: 4 chains

Explanation: According to CSA Z150 (and other similar standards), the aggregate WLL of all tie-downs combined must be at least 50% of the article's weight. For a 15-tonne (15,000 kg) excavator, 50% is 7,500 kg. With chains rated at 6,670 kg WLL, two chains provide 13,340 kg, exceeding the minimum requirement. However, best practice (often referencing provincial regulations derived from NSC Standard 10) dictates a minimum of four tie-downs for heavy equipment to address acceleration, deceleration, and lateral movement. Given the options, 4 chains is the most robust and generally accepted minimum for proper securement.