OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 9 Fall Protection

Section 144 Fall arresters

Fall arresters, commonly referred to as rope grabs or cable grabs, are used when workers need to move vertically, normally over substantial distances (see Figure 9.8) Typical users include window washers suspended from swingstages and in growing numbers, workers climbing tall ladders (see Figure 9.9). A fall arrester travels along a life safety rope or rail, following the worker’s movements. The friction created between the device and the life safety rope or rail during a fall arrests the fall. A sliding hitch knot or other system incorporating a knot is not a fall arrester.

It is important to recognize that no fall arrester can safely be used on every life safety rope. For this reason, fall arresters must only be used on compatible ropes as described in the manufacturer’s instructions. In general, there are two classes of fall arrester.

(1) Manual Fall Arresters are the simplest type. They are well suited to positioning systems on sloped roofs or travel restraint and may also be used for fall arrest systems. In positioning systems on sloped surfaces, the worker’s weight may be supported some of the time. In travel restraint, the worker needs to correctly position the device on the life safety rope so that it is impossible to reach an unprotected edge.

Manual fall arresters must be continually manually repositioned on the life safety rope as the worker moves. There is a danger that if a worker falls while manipulating the device, the worker may panic and squeeze the device – “Panic Grab” – holding it open and preventing it from locking onto the rope. To protect against “Panic Grab”, it is recommended that manual fall arresters be selected that have integral panic hardware that prevents this from happening.

Workers should be reminded to reposition their fall arrester frequently to eliminate unnecessary slack which increases fall distance, clearance requirements, and impact forces.

(2) Automatic Fall Arresters trail up and down the life safety rope as workers move vertically providing “automatic” protection. Workers do not need to manipulate these devices while moving up and down, so there is a reduced danger that the worker will “Panic Grab” the device.

The disadvantage of automatic fall arresters is that the free fall distance is increased. The standards permit the lock-off distance of the device to be up to 1 metre in the case of the referenced CSA standard and 1.4 metres for the referenced ANSI standard. In addition, when automatically trailing the worker’s movements, the device will sometimes be a lanyard length below the worker at the start of the fall, creating a free fall of twice the lanyard length plus the lock off distance of the device.

For compliance purposes, fall arresters must bear the mark or label of a nationally accredited testing organization such as CSA, UL, SEI, etc. as evidence that the fall arrester has been approved to the requirements of the Standards. Products bearing a CE mark also comply with this section. The CE mark – Conformité Européenne – indicates that the company manufacturing the product has met the requirements of one or more European directives. The product also complies with the listed CEN European standard.

The 2009 edition of the OHS Code marks the first time that Part 9 accepts fall protection equipment approved to standards from the U.S. and Europe. Fall protection equipment approved to any one of these standards is considered to offer an equivalent level of worker protection. Employers and workers in Alberta now have access to a broader range of equipment to safely meet their fall protection needs. Readers are referred to section 3.1 for information about previous editions of the standards.

Figure 9.8 Example of a fall arrester in use

Figure 9.9 Example of a fall arrester in use on a vertical structure