Rigging a Load Near a Live Conductor
A crew must set a 4,200 lb pre-cast panel on a building's third floor. The crane's boom will swing within 18 ft of an energized 13.8 kV overhead line. The site supervisor says the utility has been contacted and the line 'should be de-energized by noon.' It is now 10:15 a.m. The rigger has a tag line ready, the load is rigged with a four-leg bridle, and wind is steady at 12 mph with gusts to 20 mph. The operator has a spotter but no dedicated signal person on the far side of the building. The panel must be up before the concrete pour at 1:00 p.m.
1. What should the rigger do about the proximity to the energized line before any lift begins?
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The rigger must treat the line as energized until the utility confirms de-energization in writing or the line is visibly grounded. A verbal 'should be' from a supervisor is not confirmation. Under OSHA 1926.1408, the minimum approach distance for lines over 50 kV up to 200 kV is 15 ft, but for lines under 50 kV it is 10 ft for equipment; however, the 13.8 kV line here requires the crane to maintain the Table A distance and, if that cannot be assured, the line must be de-energized or a dedicated spotter/insulating link used per the standard. Because the boom will swing within 18 ft, the rigger should stop the lift, request written confirmation from the utility, and if not received, establish a plan with the operator that keeps the boom outside the minimum approach distance or uses a spotter whose sole job is to watch the line. The 1:00 p.m. pour is a schedule pressure, not a safety justification.
2. How does the wind condition affect the rigging plan?
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Steady 12 mph with gusts to 20 mph increases the sail area of a pre-cast panel and can cause the load to swing or rotate, which changes sling tension and can shock-load the bridle. The rigger should check the crane manufacturer's wind rating and the panel's sail area, add tag lines on two sides to control rotation, and consider whether the panel's surface area makes the lift unsafe at 20 mph gusts. If the manufacturer's limit or the site's lift plan sets a lower threshold, the lift should be postponed. The rigger should also account for the fact that gusts are unpredictable and that the far side of the building has no signal person, so the operator's visibility of the load is reduced.
3. What communication gap exists, and how should it be resolved?
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There is no dedicated signal person on the far side of the building, so the operator cannot see the load's landing point or the tag line handler. The rigger should assign a qualified signal person with a clear line of sight to both the operator and the load, using hand signals, radio, or both. If radio is used, a dedicated channel and a test before the lift are required. The rigger should not begin the lift until two-way communication is confirmed, because the operator is relying on signals to stop the load before it contacts the building or the line.