A harness system enables a person to be positioned and safely supported at a work location for the duration of the task being undertaken at height. Harness systems are used for gaining access to, and working at, a workplace where there is a risk of a fall. The most common harness systems include:
- total restraint systems
- fall arrest systems
- work positioning systems
- industrial rope access systems (see page 25 for relevant information sources)
- safety lines, lifelines, prescribed or proprietary (engineered) systems.
Total restraint system
The preferred harness system for working at height is the total restraint system (sometimes referred to as a travel restraint system). This system protects a user from approaching an unprotected edge, thereby preventing a free fall from occurring.
The system consists of equipment rated for a fall—such as a full body harness that is connected by a lanyard or safety line to a suitable anchorage point or horizontal lifeline.
Fall arrest system
A fall arrest system is designed to support and hold a person in the event of a fall. It is not a work positioning system as they are not designed to support a person while working.
Only when total restraint is impractical, should a fall arrest system be considered. Fall arrest is a minimisation measure as it does not prevent the fall from occurring. These systems require a higher level of operator competency and supervision.
A fall arrest system is an assembly of interconnected components consisting of a harness which is connected to an anchorage point by means of a lanyard incorporating an energy absorber. They can be used where workers are required to carry out their work near an unprotected edge.
When fall arrest systems are used an appropriate safety helmet shall be worn to protect the worker from head injury during an uncontrolled fall.
Work positioning systems
Work positioning systems enable a person to work supported in a harness under tension in a way that a fall is prevented. Generally the arrangement allows for the worker to maintain a stable position and to work hands-free while completing a task. The harness arrangement should not allow a fall of more than 600 mm. This is generally achieved through the use of short lanyards of 300 mm.
Minor roof repairs can be undertaken with work positioning
A permanent anchor point should be designed by a chartered professional engineer. The manufacturer and designer should ensure that each permanent anchor is uniquely identified so that its installation, testing and maintenance can be tracked during its lifetime.
Permanent anchor systems are exposed to environmental and other working stressors during their lives. They are also reliant on the condition and strength of the material they are installed into. Therefore, anchor testing and inspection regimes should consider all these factors.
The expected design life of the anchor and the required maintenance should be specified by the designer.
Anchors should have a rated load of 15 kN. All fall arrest and abseil anchors should be tagged and recertified annually to remain compliant with AS/NZS 1891.4.
A temporary anchor can include proprietary fittings or an appropriate arrangement of strops and ropes. All temporary anchors shall be set up by a competent person. Where a proprietary temporary system is used, it shall be installed in accordance with the manufacturer’s or designer’s instructions and specifications.
The roof or other building component to which an anchor is to be attached shall be checked by a competent person to verify that it is suitable for supporting the anchor.
Anchor points should ideally be positioned above head height of the worker to limit the free-fall distance. This is particularly important when using an inertia reel, as this will prevent the line making contact with an obstruction and to limit the freefall distance to that recommended by the designer/manufacturer.
All harness work requires training and competence and only trained and competent personnel can install and use harness systems on site. Persons not trained should be inducted by the system installer or other qualified persons before they are permitted to use the system. They should also be supervised at all times by another person who is also trained and competent.
For workers who are to complete basic work while under total restraint, a recommended means of achieving competence is NZQA Unit Standard 23229 – Use a safety harness for personal fall prevention when working at height, or an equivalent or higher qualification.
A recommended means of obtaining competence for workers who are involved in planning, installing, operating fall arrest systems and supervising staff is NZQA Unit Standard 15757 – Use, install and disestablish proprietary fall arrest systems when working at height or an equivalent or higher level of qualification. NZQA Unit Standard 23229 is a prerequisite for achieving NZQA Unit Standard 15757.
Minimising the potential fall distance
When a fall arrest system is being used, the potential free-fall distance should be less than two metres. Energy-absorbing lanyards should not be used in conjunction with inertia reels as this can result in an excessive distance of fall prior to the fall being arrested.
There should be sufficient distance between the work surface and any surface below to enable the system, including the action of any shock absorber, to deploy fully.
Required minimum clearance below the level of the line anchorages
Maintain minimum of slack in fall arrest line
There should not be excessive slack in the fall arrest line between the user and the attachment. The anchorage point should be as high as the equipment allows. Never work above the anchor point, as this will increase the free-fall distance in the event of a fall, resulting in higher forces on the body and greater likelihood of the arrest line snagging on obstructions.
Positioning the inertia reel anchor points
Inertia reels should be anchored above head height to prevent the line making contact with an obstruction and to limit the free-fall distance to that recommended by the designer/manufacturer. The user should work within an arc of up to 30 degrees below the inertia reel unless otherwise specified by the manufacturer.
The pendulum effect is a potential hazard with the use of harness systems. It can occur in two situations, swing down and swing back.
To prevent the pendulum effect from occurring:
- place the anchorage point at a right angle to the position of the line at the perimeter edge; a mobile anchorage is of assistance here
- use secondary anchor points and/or anchor lines
- use a perimeter guardrail to prevent any fall over the perimeter edge.
Where the pendulum effect is possible, it is better to use a work positioning system or another means of access such as an elevating work platform.
Example of a poorly placed anchor point and rope that is too long.
Example of a poorly placed anchor point that leads to swing back.
A rescue plan should be developed before installing the harness system. It is critical that a suspended worker can be promptly rescued.
A worker suspended in a harness can develop suspension intolerance. This is a condition in which blood pooling in the legs can lead to loss of consciousness, renal failure and, in extreme cases, death.
A pre-rigged retrieval system is a good way of ensuring prompt rescue. A rescue plan should consider:
- the rescue method, ie, use of a crane or elevating work platform
- available equipment
- responsibilities and training
- medical requirements
- involving the emergency service.
Workers using fall arrest systems must never work alone.
A recommended means of achieving competency for rescue planning is NZQA Unit Standard 23232 – Develop a rescue plan for recovery of a suspended individual after a fall or equivalent or higher standard. NZQA Unit Standard 23229 is a prerequisite for achieving NZQA Unit Standard 23232.
Industrial rope access
Industrial rope access is a highly specialised work method. For further guidance see:
- AS/NZS 1891 Industrial Fall Arrest Systems and Devices Series (Parts 1–4)
- Industrial Rope Access in New Zealand Best Practice Guidelines
- AS/NZS 4488.1 Industrial rope access systems – Specifications
- AS/NZS 4488.2 Industrial rope access systems – Selection, use and maintenance
- The Approved Code of Practice for Arboriculture
- IRAANZ Best Practice Guidelines Industrial Rope Access in New Zealand.
Australia/New Zealand Standards that apply are:
- AS/NZ1891.4:2009 – Industrial fall-arrest systems and devices – Part 4: Selection, use and maintenance
- AS/NZ4488.1:1997 – Industrial rope access systems – Part 1: Specifications
- AS/NZ4488.2:1997 – Industrial rope access systems – Part 2: Selection, use and maintenance.
A prescribed system is a lifeline that is designed and installed in accordance with AS/NZS 1891.2 Supp 1:2001. The end anchor loadings on these systems may reach up to 63.3 kN.
A proprietary system is a lifeline that is designed and installed in accordance with a manufacturer’s specification. These systems usually include shock-absorbing components that reduce the end anchor loadings of the lifeline. Some proprietary systems are installed with top-fixed anchors that depend partly on the strength of the roof sheeting.
An engineered system is a lifeline that is designed and installed by a qualified structural engineer. These are not as common as proprietary systems but will accommodate most fall arrest systems.