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Retractable fall arresters are commonly used with overhead anchorage lines. but nowadays, more and more models are suitable for horizontal use too.

This means those models can also be used on roofs, where anchor lines or anchor points are located at the height of the worker’s feet.

So what is the best connecting device for a work restraint system on a roof? In what situations can a retractable fall arrester be used? Here are a few difference between the various connecting devices.

Work restraint

Those who know a thing or two about fall protection may know that there are two different ways to use fall protection anchorage on a roof: for work restraint systems or for fall arrest.

From a safety point of view, work restraint should always be preferred over a fall arrest situation because the former is a preventative measure; the length of the connection prevents users from reaching a position from where a fall could occur. This is common practice for work on flat or near-flat roofs.

Lanyard and rope grab

When the distance between the anchor point and the work location varies or is more than two metres, a different kind of connection is needed. In these situations, the traditional method is to use a long lanyard (rope) with a rope grab and a personal energy absorber (PEA).

work-restraint-system-where-the-length-of-the-lanyard-connection-is-set-with-a-rope-grab

Work restraint system where the length of the lanyard connection is set with a rope grab.

A PEA is used to limit the fall arrest shock. But why is a PEA needed to absorb the fall arrest shock in a work restraint system that prevents a fall from happening in the first place?

Simple: because in these situations, the human factor is always a risk.

Using a rope with a rope grab requires a user to manually set the length of his connection. Of course, a work restraint system with an adjustable length entails a certain risk of misuse. This risk is covered by a PEA.

So except in situations where fixed-length lanyards are used, there is no physical difference between a rooftop personal fall protection system used for work restraint and one that is used for fall arrest.

In theory, this shouldn’t be a problem because personal fall protection may only be used by trained and qualified workers who know exactly what they’re doing. Still, the system should be capable to arrest their fall if they misuse the system or make a mistake.

Retractable fall arresters for horizontal work restraint

A personal fall protection system on a roof needs to provide users the possibility to set a limit for them, and to arrest their fall just in case.

Retractable fall arresters come in different lengths, so notwithstanding their name, they could just as well be used for work restraint purposes so long as the maximum length of the cable (or webbing in some cases) is equal or smaller than the distance to the edge. But why would you?

The main reason to consider using a retractable fall arrester for work restraint purposes is that a fall arrester ensures a taut connection. Users don’t have to adjust the length of their connection; the fall arrester unrolls as they move further away, and retracts as they move back.

construction

With a rope grab, users are required to perform a manual corrective action every time the rope becomes slack. Users would have to set the length of their connection by adjusting the rope grab which is attached to the back of their harness. Users also have to deal with the excess rope.

Although both solutions offer an equal level of safety (on non-fragile roof surfaces), one could argue that a retractable fall arrester is a more convenient solution.

The downside of a retractable fall arrester however, is that it can only restrain users at its maximum range; it cannot be set to restrain users at intermediate lengths. By contrast, a rope grab can be set at any point on the lanyard.

So, when does one opt for a retractable fall arrester with a permanent fall protection system?

When the permanent roof anchorage is at a fixed distance (more than two metres) from the edge, a retractable fall arrester is an excellent way to achieve maximum usability and to make sure workers cannot misuse the work restraint system. This is unquestionably a value-add.

However, if the work restraint range on your roof differs, then buying a retractable fall arrester is probably not worth it unless your roof contains a lot of fall-through hazards. A rope grab and lanyard is still a safe and cost-effective solution that can be used in almost any situation.

 
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