3.6 Fall arrest systems

A fall arrest system is used where there is a risk of a free fall and the system must catch, decelerate and stop the fall.

Unlike a restraint system, it does not necessarily prevent the user from falling.

Its purpose is instead to limit the consequences when a fall occurs.

The arrest force must be limited

A fall arrest system must limit the force transferred to the user when the fall is stopped.

In a personal fall protection system for fall arrest, the force on the body must be limited to a maximum of 6 kN.

This is achieved by a component or function that absorbs energy during the arrest.

Products and standards

A fall arrest system may, for example, include:

Anchorage An anchorage point, anchorage device or structure that meets the requirements for the selected connection.

Harness Full body harness – EN 361.

Coupling For example:

energy absorber – EN 355,
retractable type fall arrester – EN 360,
guided type fall arrester including a rigid anchor line – EN 353-1,
guided type fall arrester including a flexible anchor line – EN 353-2,
connector – EN 362.

The manufacturer's instructions define which products may be used together and under which conditions.

Clearance must be verified

A fall arrest system needs sufficient space to stop the user before the person strikes the ground, a structure or another obstacle.

The required clearance depends on factors including:

the product or system being used,
the length of the connection,
deployment of any energy absorber,
the position of the anchorage,
the user's position,
system elongation and movement,
the safety margin specified in the manufacturer's instructions.

Clearance must therefore be verified using the instructions for the actual product or system – not estimated.

Anchorage position affects the fall

The greater the free-fall distance before the system begins to arrest the user, the greater the load on the system and the longer the total fall distance.

The anchorage should therefore be positioned to minimise the free-fall distance and reduce the risk of a swing fall.

Remember

A fall arrest system does not prevent the fall – it catches, decelerates and stops it.