A fall arrest system should include three main components:
Anchor point is first and at the same time essential component of whole fall arrest system. It is a point in the work area that is responsible for connecting the permanent rigid construction with the connecting and energy absorbing parts of fall protection system. The requirements for the anchor point are given in EN 795. One can divide the anchor points into few categories – permanent anchor points (fixed to the construction - examples are permanent systems with anchor line), movable anchor points (not fixed to construction – examples are tripods, adjustable anchor beams). Anchor points have to be connected with rigid construction which has proper strength and stability.
Energy absorbing and connecting components
Those are components of the system which link the anchor point with the attachment point in the harness. When a fall occurs those components have to stop the fall and at the same time limit the maximal force which occurs during breaking of the fall. The kinetic energy produced during the fall is absorber and the maximal force is limited to safe values (below 6kN). This eliminates the risk of suffering serious injuries during the fall. Products which can be used to meet those goals are for example: self-retracting fall arresters, energy absorbers with lanyards and other.
The basic task for the safety harness is to keep the human body during the fall and to distribute the forces which occur during stopping the fall. After arresting the fall next important point for the safety harness is keeping the body in a position that is safe and fairly comfortable during waiting for the help. The construction of the safety harness is strictly described in EN 361. All harnesses used as personal protection equipment against fall from height have to fulfill those requirements. Only full body harness with shoulder straps and leg straps can be considered as PPE. Usage of work positioning belts, waist belts or sit harnesses designed for sport applications is forbidden.
Well-designed full body harness should be ergonomic and offer comfort for the user. Depending on the type of harness there can be just one attachment point (usually dorsal) or there can be more attachment points to which connection can be done. Harness can additionally have a waist belt with attachment buckles for fork positioning. Number and location of attachment points influences the functionality of the harness.
Application of fall arrest system is recommended to use only if there is no other method to guarantee safety for the workers. The main role of the fall arrest system is to safely stop the fall and limit the risk of injuries during fast deceleration. The fall arrest system does not prevent the fall.
To ensure sufficient safety level, during configuration of fall arrest system, one has to consider following aspects:
Minimal free space
Safe arresting of a fall has to be done in the air. If contact with the surface, ground or some construction components will occur during the fall the consequences are usually serious injuries or even death. To avoid such risk a free space below the user has to be granted. As a free space we describe space that is without any objects that can be hit by a falling person. To define the space needed one has to take into consideration the energy-absorber, connection components and the location of anchor point in respect to location of the person.
Location of anchor point
The fall distance should be always as short as possible. Location of the anchor point in respect to the location of the user has significant meaning for the fall distance. If the anchor point If the anchor point is placed over the user than the fall distance will be limited. On the contrary if the anchor point is below the user the fall distance will be greatly extended what may lead to contact with surface which is below and can increase the forces during fall arrest. In a situation where the user has a choice of anchor points he should chose the one which is placed as high as possible.
This is a dangerous situation in which during a fall the movement has a pendulum character. It may result in contact of the user with objects which are placed not directly below the user (considering the start of the fall) but located on sides. The pendulum effect is greatly increased with the movement of the user from the vertical line lead from the anchor point. The pendulum effect can lead to improper work of some components of fall arrest system – ex. self-retracting fall arresters. When choosing the anchor point one has to take into consideration to limit the pendulum effect
As the risk evaluation has to take into consideration parameters of the fall arrest system component sit is highly recommended to read all manuals, attached to the safety system components, before the use.