Working at Height on a Roof-Mounted Unit
Your team must service a ventilation unit mounted on a flat roof 6.5 m above ground. Access is via a fixed internal ladder through a roof hatch. The roof has no parapet; the edge is 3 m from the unit. Weather forecast shows gusts of 55 km/h in the afternoon. The team consists of one experienced technician and one apprentice in the second month of training. The customer wants the job done today because the unit serves a production hall. The only fall-protection equipment on the van is two harnesses with lanyards and one 10 m lifeline; the anchor points on the roof have not been inspected since last year.
1. Decide whether the job can proceed today. Structure your answer around the hierarchy of control measures for work at height.
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The hierarchy for work at height is: avoid work at height where possible, prevent falls using collective measures, then mitigate residual risk with personal protection. Applying it:
Avoid: can the service be done from below, or can the unit be lowered or a remote inspection used? If the manufacturer allows servicing from an internal access panel, do that. This should be checked first.
Prevent: collective measures such as a temporary guardrail or platform around the unit and along the edge would be the correct solution, but none is on site and none is planned.
Mitigate: personal fall protection only as a last resort, and only with inspected anchors, a rescue plan and trained users. Here the anchors are uninspected, there is one lifeline for two people, and no rescue concept exists. That fails the requirement.
Additional factors: gusts of 55 km/h make roof work unsafe and can make lanyard use unpredictable; the apprentice is not trained or competent for fall protection.
Decision: do not proceed today. Postpone, arrange collective edge protection and anchor inspection, and reschedule for calm weather. Inform the customer in writing of the safety reason and offer a temporary alternative for the production hall.
2. The customer insists the unit must run today. What can you lawfully offer, and how do you handle the apprentice?
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You cannot trade safety for production pressure. The employer's duty to protect employees is not waivable by customer instruction, and the technician has a right and duty to refuse unsafe work.
Lawful options to offer: (1) a temporary measure that keeps the hall running without roof access, e.g. operating the unit at reduced setpoint, using a mobile stand-by ventilation unit, or adjusting controls from the safe internal panel; (2) an emergency call-out by a contractor equipped with a mobile elevating work platform and certified fall protection, at the customer's cost, if the risk justifies it; (3) a documented appointment within 24–48 hours once edge protection and anchor inspection are in place.
The apprentice must not be deployed on the roof at all. Second-month apprentices may only work under continuous supervision on tasks appropriate to their training; fall-protection work on an unprotected roof is outside that. Keep the apprentice on ground-level tasks, e.g. preparing tools and documenting.
Finally, record the refusal and the reason in the job file, notify the customer in writing, and report the missing equipment and uninspected anchors to your supervisor so the gap is corrected before the next job.