Climbing the Mast Beside a Live Feeder
A hammerhead crane is being climbed from 60 m to 72 m using a hydraulic climbing frame. The mast is 2.0 m square, and the next six standard sections are staged on the deck below. A site survey drawing shows an 11 kV overhead line running parallel to the site boundary, with the nearest phase conductor 14 m horizontally from the mast centre at the climb height. The manufacturer's minimum approach distance for the crane structure is 6 m for lines up to 33 kV, but the electricity operator's safe clearance for plant is 9 m. The wind forecast is 9 m/s gusting 15 m/s; the climbing procedure states climbing must stop if wind exceeds 10 m/s. The climbing crew of three includes one banksman. The crane's slew is locked and the jib is parked over the site, not over the line.
1. Identify the controlling clearance figure and state whether the climb can proceed today.
Read the worked answer
Two clearance figures apply: the manufacturer's 6 m minimum approach and the electricity operator's 9 m safe clearance for plant. The higher, more restrictive figure governs - 9 m. The actual horizontal separation is 14 m, so the structure remains outside the operator's clearance even at full climb height, provided the jib and any suspended equipment stay on the site side and the slew lock holds. However, the climb should not proceed today on wind grounds: the gust of 15 m/s exceeds the procedure's 10 m/s stop limit. The climb should be deferred until gusts are forecast below 10 m/s. The 14 m clearance is a margin to be confirmed by the operator in writing, not assumed from a survey drawing.
2. What controls should be in place before the climb restarts?
Read the worked answer
Confirm in writing with the electricity operator that 14 m is acceptable and whether any isolation or diversion is required; do not rely on a drawing alone. Re-brief the crew on the 9 m controlling distance and the exclusion zone, and confirm the banksman has an unobstructed view of the line and the climbing frame. Verify the slew lock, the climbing frame pins and the hydraulic system per the procedure, and check that no tools or sections can be dropped toward the line. Re-check the wind at the start and throughout, with a stop-work trigger at 10 m/s gust. Record the climb, the wind readings and the clearance confirmation.