Concrete Pour at the Boundary Fence
You are the crane operator on a 55 m jib tower crane at a residential site. The pour is running late and the concrete crew is impatient. The pump has moved to the far corner, so the kibble must be flown over a 2.4 m boundary fence to reach the last slab panel. Beyond that fence is a public footpath, a bus stop and a 11 kV overhead line running parallel to the fence at about 6 m above ground, roughly 9 m from your slew centreline. The rigger asks you to 'just swing it over quickly between buses'. Wind is 14 km/h gusting to 22 km/h from the direction of the line. Your load chart for the working radius gives 3.2 t capacity; kibble plus concrete is 2.6 t. The lift plan on site does not address the line.
1. What is your immediate decision and what is the reasoning behind it?
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Refuse the lift as proposed and stop work in that area until the hazard is controlled.
The reasoning is not simply 'powerlines are dangerous'. Three things combine here:
- No control for the line. An 11 kV line within the slewing arc requires a documented control: de-energisation and isolation with a permit, or exclusion zones established by a competent person, with the crane's slew limit set so no part of the jib, rope or load can enter the zone. None of that exists. The absence of a lift plan covering the line is itself a compliance failure, not a personal preference.
- The public footpath and bus stop. Even if the electrical risk were managed, the load would pass over members of the public. That is a separate unacceptable risk that the site has not assessed or controlled with an agreed diversion and marshalling.
- Capacity margin is irrelevant to the real hazard. 2.6 t against 3.2 t is a comfortable static margin, but wind acting on a kibble and the dynamic effects of a quick swing reduce effective control. A 'quick swing between buses' is precisely the kind of task where the operator loses the ability to stop the load where they intended.
Correct sequence: lower the load to a safe landing area, inform the supervisor and the crane coordinator, request that the line be de-energised or the slew limited, and require a revised lift plan for the boundary panel. The pour can continue on panels that do not require the boundary swing.
2. The site supervisor tells you the line is 'only 11 kV, low voltage' and to proceed. How do you handle this, and what does the legislation expect of you?
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'Only 11 kV' is a misunderstanding: 11 kV is a high-voltage distribution system and is lethal at any realistic contact distance, and arcing can occur without direct contact.
My response is procedural, not argumentative:
- State clearly that I am not proceeding, and record the refusal with the time, the reason and who gave the instruction.
- Escalate to the principal contractor's crane coordinator or safety representative, and to the person with control of the site. The duty to provide a safe system of work sits with the person conducting the business or undertaking; the operator's duty is not to operate plant in an unsafe manner.
- Ask for the control in writing: either the isolation permit from the network operator, or the documented exclusion zone and slew limitation signed off by a competent person.
- If the instruction is repeated, I stop the crane, secure it and leave the controls. An operator cannot be directed to perform an unsafe lift; the instruction is not a lawful direction.
The exam point is that a supervisor's assurance does not transfer the risk. The operator remains accountable for the lift they choose to make.