Home Prove Your Know How Last line of defence

Issue 50 – March 2016

Last line of defence

16 Feb 2016, Prove Your Know How, Safety

Falls from three metres or less off roofs and ladders account for a large number of the construction sector’s serious harm accidents. Harness systems are an effective way to minimise these falls, but should be used as a last resort

Employers must take all practicable steps to ensure their workers are safe, and residential building sites account for more injuries in the industry than any other worksite.

It’s important that a full evaluation of the job takes place before beginning work at height. Go through the ‘hierarchy of controls’ (eliminate – isolate – minimise) and work out the best possible option to control the height risk.

The ‘Task Analysis’ worksheet is a planning tool which requires workers to specify the step-by-step activities that will occur and how they can be done as safely as possible. Opt for safe working at height equipment systems, such as scaffolding, edge protection or mobile elevated working platforms.

Harness safety systems should be a last possible option because they are a form of injury minimisation.

Fall Restraint: The preferred harness system

A fall restraint system prevents workers from reaching the edge. Falls are prevented by having the worker restrained through a full-body harness, which is connected to an energy-absorbing lanyard and suitable anchor point. Restraint systems require less training and competency than other harness systems, but restrict a worker’s movement.

Fall Arrest: The last line of defence

A fall arrest harness provides more movement and allows the worker to reach the roof edge. A shock-absorbing lanyard will break any fall and allow the person to either self-rescue or be rescued.

Additionally, consider the ‘swing fall’ effect. Fixed lanyard anchors need to be at least 6m above the ground to eliminate the potential of hitting the ground or objects if a worker does fall.

It’s vital that a rescue plan be put in place before using a fall arrest system. The harness puts pressure on the fallen worker’s circulation, so a quick and efficient rescue is needed.

Work positioning systems

A work positioning system is often used when there is no solid surface to stand on and a worker is suspended at height. A lanyard is attached to both the worker’s harness and their place of work, so that the worker can lean back and have the lanyard support their weight. This system allows its user to have their hands free to focus on the task, such as line-work. A fall arrest system should be used in conjunction with work positioning systems.

Assess your team, your plan and the worksite

Before commencing work with a harness system, ensure that training, anchors, lanyards, harnesses and rescue plan is current, relevant to the specific job, and compliant with standard AS/NZS 1891.4:2009.

Other important factors to consider when selecting the appropriate harness systems are the competence of your workers (a combination of their training, knowledge and experience); and rescue planning, which is based on your site-specific capability.

It’s vital to supervise workers using harness systems until deemed competent. When considering whether a worker is competent or not, think about whether the worker can confidently demonstrate and understand:

  • How to correctly fit and attach safety harnesses.
  • The danger of using incompatible hardware (for example, harnesses and lanyards from different systems).
  • How to inspect, maintain and store the equipment.
  • How to correctly anchor, install and use the total restraint system.

Always work in teams when using harness safety systems, and implement a rescue plan before starting work. Assign responsibilities to everyone on site, so they know what to do in case of a fallen worker.

Also complete a ‘Notification of Particular Hazardous Work’ with WorkSafe New Zealand when carrying out work above 5m and ensure you notify them 24 hours before starting the job. Remember, these systems are the last option if you cannot use another method of working at height like scaffolding or edge protection.

Site Safe offers a height and harness course, which covers the unit standard 23229 ‘Use a safety harness for personal fall prevention when working at height’ and discusses the use of these height and harness systems and others.

Site Safe’s ‘Site Specific Safety Plan’ includes a ‘Task Analysis’ worksheet and is free to download from sitesafe.org.nz/sssp


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