Excavator Operator Certification Exam Prep · Question
A trenching project requires the use of a trench box. The competent person has determined that due to the soil conditions, a 'modified' trench box setup is needed, allowing for limited excavation below the bottom of the box. According to safe work practices, what is the maximum depth below the bottom of a trench box that excavation is permitted to extend into stable soil conditions?
While trench boxes should ideally provide full depth protection, in specific stable soil conditions and with competent person approval, excavation up to 0.3 met
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Question: A trenching project requires the use of a trench box. The competent person has determined that due to the soil conditions, a 'modified' trench box setup is needed, allowing for limited excavation below the bottom of the box. According to safe work practices, what is the maximum depth below the bottom of a trench box that excavation is permitted to extend into stable soil conditions?
Answer options: ✅ 0.3 metres (12 inches)
- 0.6 metres (24 inches)
- 0.9 metres (36 inches)
- 1.2 metres (48 inches)
Correct answer: 0.3 metres (12 inches)
Explanation: While trench boxes should ideally provide full depth protection, in specific stable soil conditions and with competent person approval, excavation up to 0.3 metres (12 inches) below the bottom of the box is sometimes tolerated, as per CSA Z248 guidance and OHS safety notes, but never more due to risk of undermining.
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Question explanations
- During a final inspection of an excavator, prior to beginning work, an operator notices significant play in th
- An excavator operator is preparing to dig a trench in cohesive soil. To achieve maximum breakout force, what a
- Which control typically governs the arm (or dipper arm) movement for an excavator?
- What condition might require sloping or shoring of a trench less than 1.2 meters (4 feet) deep?
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