OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 9 Fall Protection

Sections 152 to 152.4 General comments about anchors

Parts of structures located in the vicinity of where a worker is working are often used as improvised anchors (as opposed to engineered anchors) for travel restraint and fall arrest systems (see Figure 9.16). Improvised anchors are not manufactured to any technical standard. Improvised anchors may include a beam, struts of a communication tower, a concrete Jersey barrier, a sizeable tree, a locked out and chocked vehicle, or other similar, robust structures.

Workers required to use fall protection equipment must be trained to understand how to safely protect themselves. These workers must be able to assess an anchor’s strength, stability and location.

Figure 9.16 Example of I-beam used as an anchor point with sling specifically designed for this purpose

Workers may tug or reef on a potential anchor as a test to see if it will hold. This “test” is completely inadequate as the force generated during a tug rarely approaches even half the worker’s body weight. A better approach might be to imagine a passenger vehicle being supported from the anchor by a lanyard. If the vehicle, having a weight approaching 1600 kilograms (3600 pounds) can be held, then the anchor is a good one. The anchor must be “bomber” or “bomb-proof”.

If an anchor is located on a mobile or erected structure such as a bucket truck, manlift or scaffold, the stability of the structure needs to be considered in the event of a fall. The structure must not topple over and create more safety problems.

Swing fall hazards must be considered when selecting an anchor. Ideally, work should be performed directly below the anchor. The further a worker is away from this ideal position, the greater the potential for the worker to swing like a pendulum into objects if the worker falls (see Figure 9.14). In situations where swinging cannot be avoided, but where several equally good anchors are available, the anchor selected should direct the swing fall away from objects rather than into them. Where there is a choice among anchors, the one offering the least amount of swing should be selected.

A drop during a swing may result in the worker impacting the ground or other obstructions. Furthermore, the horizontal speed at the bottom of the swinging arc is exactly the same as the vertical speed if the worker had fallen the height dropped during the swing. For this reason, the CSA Standard Z259.16 recommends establishing anchorage locations so that the swing-drop distance is limited to 1.2 m or less.

Table 9.1 summarizes the strength requirements of anchors as required by sections 152 and 152.1

Table 9.1 Summary of anchor strengths required by section 152 and 152.1

Fall Arrest
Anchor Strength
(temporary or permanent)

Travel Restraint Anchor Strength

Temporary

Permanent

16 kN
or 2 x Maximum Arresting Force
(MAF)

3.5 kN

16 kN
or 2 x MAF
 
Since there is no category for “permanent travel restraint anchor”, these anchors default to being fall arrest anchors.