Rooftop Microwave Install with Corroded Battery
A crew is installing a rooftop pole for a point-to-point microwave link on a six-storey building. The roof has an existing lightning rod, but the new pole is 4 m from it. Wind is 30 km/h gusting 45 km/h, and the roof edge has no parapet. The crew has a 6 m fibre-glass ladder, full-body harnesses, and a work permit that expires at 16:00; it is 15:30. The customer wants the link aligned before a 17:00 event. In the equipment room, a 48 V string of 24 VRLA blocks has two blocks with white powder at the terminals. The crew also plans to drill into the wall for cable entry while the equipment is live.
1. Identify the stop-work triggers and explain which one is most immediate.
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Stop-work triggers: wind gusting to 45 km/h against a climb limit, a roof edge without a parapet, a permit expiring in 30 minutes, live-equipment drilling, and battery corrosion. The most immediate is the wind and fall hazard: a gust can destabilise a ladder or climber, and a 6 m ladder on a six-storey roof may not be the right access for the pole. The permit expiry also means there is no valid window to complete the task. The customer's 17:00 event does not override the safety controls. The crew should secure the area, stop drilling, and report the delay. If any work can be done safely at ground level, such as isolating power or inspecting the battery, do that; do not climb or drill live.
2. Set out the correct sequence for the rooftop work, including RF, fall protection, and permit controls.
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First, re-plan and reschedule with a valid permit, a weather window below the tower/ladder limit, and a rescue plan. Isolate and lock off the microwave transmit power before anyone enters the antenna near field, and verify with an RF monitor. Establish fall protection: full-body harness with twin lanyard to a rated anchor, edge protection, and a trained spotter; use a suitable MEWP or scaffold rather than a loose ladder where possible. Bond the new pole to the building's lightning protection and earthing system with the correct conductor and clamps, maintaining separation from the existing rod. Only then install, align, and torque connectors. Restore power and test after everyone is clear.
3. What should be done about the two corroded VRLA blocks and the wall drilling?
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Treat the white powder as lead/acid contamination, not ordinary dust. Wear acid-resistant gloves, goggles, and a respirator if dust is disturbed; do not dry-sweep. Isolate the battery string, remove the affected blocks with insulated tools, bag them, and label them as hazardous/e-waste for authorised recycling. Do not mix old and new blocks in the same string without manufacturer approval; replace the string or matched blocks and retest. For the wall, stop drilling until the wall is assessed for asbestos and hidden services; use a permit and isolation for any live equipment. If asbestos is suspected, a competent person must sample it and a licensed contractor must handle it.