Discebo

Introduction

A lift affects a larger area than just the load's path from A to B. The load can swing the crane turns and in case of failure the load falls straight down. That is why safety is thought in zones: where may people be and where may they not. Managing the zones is just as important as the lift itself.

Hazard zone under and around the load

The area under a suspended load is always a danger zone — if the rigging fails, the load falls straight down. But the zone is wider than that: the load can swing or rotate, and there must be space for it to move without hitting anyone. The danger zone is kept clear of people throughout the lift, and the path of the load is planned so it is not led over people.

The swing area behind the crane

On mobile cranes and many truck cranes, the counterweight and rear swing out when the crane rotates. A person standing close to the side or behind can be pinched between the crane's rotating part and a fixed object — even if the load is somewhere else entirely. Therefore, the swing area is cordoned off so no one can get caught in the space the crane rotates into.

Why overhead lines are particularly dangerous

Electric overhead lines and railway catenary are one of the most serious hazards when working with cranes in the open. Current can jump over an air gap so you don't need to touch the wire to get a shock — if boom, cable or load gets too close, current can flow through the crane and on to the person standing by it. The consequences can be fatal.

Safety distances — the figures

The executive order on non-electrical work near electrical installations (BEK no. 1112 of 18/08/2016) sets fixed distances to overhead lines. They are called safety distances, and they must not be crossed (§ 5). Low voltage is up to and including 1,000 volts AC; anything above is high voltage (§ 2).

What	Distance	Rule
Horizontal, measured from the ground	3 m	§ 5, subsection 2
Vertical, low-voltage overhead line and overhead cable	1.5 m from the outermost conductor	§ 5, subsection 3, no. 1
Vertical, high-voltage overhead line of 10-40 kV	6 m from the outermost conductor	§ 5, subsection 3, no. 2
Vertical, high-voltage overhead line over 40 kV	15 m from the outermost conductor	§ 5, subsection 3, no. 3

Keep the whole crane — boom, wire rope, hook and load — outside the safety distance, also when the crane slews. Other distances apply to railway overhead contact lines. They are in the safety instructions from the railway infrastructure manager (§ 2, no. 11).

When the distance cannot be kept

01Clarify whether there are air lines or overhead power lines in and over the work area before the crane is set up
02If the work cannot be done without coming within the safety distance, you must obtain instructions from the owner of the electrical installation before you start (§ 6).
03You may work above a low-voltage overhead line or low-voltage overhead cable when there is at least 1.5 m down to the line at all times (§ 7).
04Never touch a faucet that has come into contact with a wire — keep distance and warn others

If the crane hits a conductor

An electrical installation must be regarded as live until the owner has declared it dead. If the crane, the wire rope or the load has touched the line, or there has been a flashover, the crane is also regarded as live (§ 14). The voltage can spread in the ground around the crane. That is why it is dangerous both to touch the crane and to walk close to it.

01Stay on the machine until the voltage has been removed from the line. BFA Bygge & Anlæg writes this about excavators, and it also applies to the crane.
02Keep everyone away: at least 10 m from live objects and fallen lines at high voltage and 2 m at low voltage (§ 15).
03Notify the owner of the installation as soon as possible: where it happened and what happened (§ 16). Call 112 if necessary.
04Stand guard and warn others of the danger until the owner, the owner's representative or the police have arrived (§ 16, subsection 2).