Electricity does not require contact. A crane boom brought close enough to a high voltage line can flash over through the air, and the first warning is the incident itself.

The boom is the hazard, not the load

Most planning attention goes to where the load will be, but the boom sweeps a far larger volume and reaches higher than the load does. A jib that clears a line comfortably when the load is at the pick can be much closer to it once the crane slews or the boom is raised. The zone that matters is the one the whole machine can occupy, including the hook block, any hanging slings and a swinging load.

Exclusion first, competence second

The reliable control is keeping the machine out of the area entirely, by isolating the line, by physically preventing the crane from reaching it, or by choosing a position from which it cannot. Barriers, goal posts and travel restrictions do this. Relying on the operator judging the distance by eye does not, because distance to an overhead line is very hard to judge from a cab, particularly against a plain sky and particularly when the operator is concentrating on the load.

If contact happens

The safest place is inside the cab, and the operator stays there. The ground around a machine in contact with a live conductor is energised, with the voltage falling away with distance, so a person standing near it can have a large difference in potential between their feet. Anyone approaching to help completes a path. If leaving the machine is unavoidable because of fire, the method is to jump clear without touching the machine and the ground at the same time, then to shuffle away with the feet together rather than to run.

Structures do not conduct but they do surprise

Buildings, other cranes, scaffolds and lighting columns present a different failure: the boom or the load contacts them during a slew that looked clear at the pick. Where two cranes have overlapping radii, the arrangement needs a rule about who has priority and a physical or procedural limit, not an assumption that the two operators will see each other. A load swinging on a long fall has a far larger reach than its static position suggests.

Underground and overhead are the same question

A crane set up beside a trench, over a buried service, or on a basement slab is loading something that may not carry it. The imposed load through an outrigger is concentrated and much higher than the machine’s weight suggests, and it is the reason outrigger pads exist. Checking what is beneath the setup position belongs in the same conversation as checking what is above it.

For the tree-work equivalent of this clearance problem, see working near overhead lines during tree work. For what is buried under the setup, see locating and avoiding buried services.

Related standards

The standards below set the safety requirements, marking and discard criteria behind the equipment used for this work.

• EN 397 — Industrial Safety Helmets
• EN ISO 20471 — High-Visibility Clothing

Frequently asked questions