339B Tower Crane Operator Practice Quiz
Free · 150 Questions.

Question 1

A climbing tower crane is being erected beside a street. The counter-jib could swing within reach of an energized overhead line with a nominal phase-to-phase rating of 27,600 volts. What is the minimum distance that no part of the crane or its load may be brought closer than?

• A. 1.5 m
• B. 3 m
• C. 4.5 m
• D. 6 m

Explanation: Section 188(2) sets 3 m for conductors rated 750 V or more but no more than 150,000 V. 4.5 m applies only above 150,000 V up to 250,000 V, and 6 m only above 250,000 V.

Question 2

Wind speeds are rising during a morning of lifting formwork panels, and the site foreman says the crew has always finished these lifts in worse conditions. Whose limits does the tower crane operator work within for weather conditions such as wind, lightning or hoar frost?

• A. The manufacturer's specifications, CSA Z248 and jurisdictional requirements
• B. The foreman's experience and the conditions the crew has worked in before
• C. The limits the rigger sets for the particular load and sling arrangement
• D. The weather limits published for the mobile crane working on the same site

Explanation: The Red Seal standard has operators follow limits with due caution in weather according to the manufacturer's specifications, CSA Z248 and jurisdictional requirements. Neither a foreman's habits nor another machine's limits replace those.

Question 3

A precast concrete block measures 2.5 m long, 1.2 m wide and 0.8 m high. Concrete has a unit weight of 2,400 kg/m3. Using the cube formula L x w x H x U.W., what is the weight of the block?

• A. 4,800 kg
• B. 5,760 kg
• C. 2,400 kg
• D. 7,200 kg

Explanation: Volume = 2.5 x 1.2 x 0.8 = 2.4 m3, and 2.4 x 2,400 = 5,760 kg. 7,200 kg leaves out the height and 4,800 kg uses a wrong volume.

Question 4

A precast wall panel weighing 12,000 kg is lifted by a tower crane with a symmetrical two-leg bridle. Each leg makes an angle of 60 degrees with the horizontal (sin 60 = 0.866). What is the tension in each leg, to the nearest kilogram?

• A. 6,000 kg
• B. 6,928 kg
• C. 8,485 kg
• D. 12,000 kg

Explanation: Leg tension = W / (2 x sin angle) = 12,000 / (2 x 0.8660) = 12,000 / 1.7321 = 6,928 kg. 6,000 kg ignores the angle, and 8,485 kg is the value for 45 degrees.

Question 5

A long load has an off-centre centre of gravity (CoG) that the rigger has marked. Where should the operator position the hook block before the slings are tensioned?

• A. Over the geometric centre of the load's plan, whatever the CoG
• B. Over the nearest rigging attachment point
• C. Slightly toward the mast so the load swings in when lifted
• D. Directly over the CoG of the load

Explanation: The hook is centred over the CoG of the load (E-12.03 and E-12.04). If it is offset, the load tilts or swings horizontally when picked, creating an uncontrolled movement.