Fall Factor & Fall Clearance

Heightsafe strive towards becoming the UK’s main company for Work at Height safety and education. We want to inform employers on the health and safety responsibilities attributed to their business and raise awareness of the importance of adequate height safety for their personnel. That is why it is important to learn about Fall Factor & Fall Clearance, and it is essential to consider this when selecting a Fall Protection solution.

Fall Factor & Fall Clearance

Contrary to popular belief, selecting the correct Fall Protection and the corresponding PPE for your operatives is a straight forward process, but it can be made even easier because of these three factors:

Fall Factor
Fall Clearance
The Risk of a Swing Fall

You must consider these three factors before choosing a Fall Protection System, as it could be the difference between your personnel being safe or at risk.

Fall Factor

A Fall Factor is defined as the ratio between the height of a fall and the length of the lanyard that is being utilised to absorb the shock of a fall. To calculate a Fall Factor, you must assess your Fall Protection equipment and then select a value that varies between 0 and 2. This is decided by dividing the height of the fall by the length of the lanyard. The measurement of the height is determined from where an operative falls to the point where the fall is either restrained or results in an impact.

If the Fall Factor is lower, there is less impact on the body of the operative using the system. In turn, this determines that the fall provides a minimal risk of injury. If the Fall Factor is higher, it means there is a greater impact on the body, which could result in serious injury or even death.

Note: the Fall Factor indicates the severity of the fall, not the measure of impact.

The Fall Factor score is determined below:

Fall Factor 0 – Overhead, the lanyard is pulled tight above the body.

Fall Factor 1 – Located at the height of the operative’s back. The lanyard is on the back of the body, or somewhat lower.

Fall Factor 2 –The lanyard is at waist height or as low as your feet.

Fall Clearance

The Fall Clearance is determined by the minimum vertical distance needed between the end-user’s feet and a lower level of the structure (or obstacle) to ensure the operative is prevented from an impact.

It is important to note that the calculated Fall Clearance of a Fall Protection System may never be equal or higher than the available clearance. For example, if the Fall Clearance is six metres, but the lower level is only a distance of five metres, this would mean an operative using the system will still impact with the solid ground below.

There is a formula to calculate the Fall Clearance of a system. This is:

Fall Clearance = Free Fall Distance + Arrest Distance + Harness Stretch + Safety Factor

Swing Fall or The Pendulum Effect

In addition to the above about the Fall Factor and Fall Clearance, Swing Falls (also known as the Pendulum Effect) must be taken into consideration by an employer.

The risk of a Swing Fall (or Pendulum Effect) occurs when the end-user of a Fall Protection System is a considerable distance apart from their Anchorage device. This is because the distance between the operative and their Anchorage device increases, meaning the length of their lanyard also increases. In the event of the operative falling from a height, the long lanyard can cause the operative to swing considerably, and in turn, they could strike a nearby surface.

The lanyard’s length also affects the swing’s speed. The longer the lanyard, the faster the speed of the swing. This speed, alongside a possible impact, can result in a significant injury or the death of the operative using the system.

Influence on Decisions

When deciding on what Fall Protection System you should use, the Fall Factor, Fall Clearance and the possibility of a swing fall can determine which solution is safest to apply.

If the fall is from a greater height, there is more chance of a swing fall, meaning there is a greater need to use a shock absorber. The Fall Clearance is variable and can always be determined by the Fall Factor, the situation and the type of Fall Arrest device that is used. When there is a greater risk of a swing fall, extra Fall Protection measures must be applied to minimise the danger for the user.

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