FREQUENTLY ANSWERED QUESTIONS – FROM SAFETY NETS NZ
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When thinking about the netting, consider how and where they will be attached below the work area. Safety netting is most suited to steel or timber framed buildings where the nets can easily be attached.
Safety nets must never be attached to handrails unless they have been designed to take a minimum 6kN load at 45 degrees to the vertical.
BSEN 1263-2:2002 Safety Requirements for the Positioning Limits
states that the maximum permissible fall height into a safety net is 6m from the work position, which means that the maximum nominal fall height from the centre of gravity of a person is 7m. It should be noted that for safety nets less than 35m2 in total area, or a side length less than 5m, the maximum height an operative is allowed to work above a net is 2m as there is insufficient fabric area to absorb the energy falls from a greater height.
Regulation 6 of the Work at Height Regulations 2005
deals with the avoidance of risks from working at height. The regulation requires that where falls cannot be prevented, then measures are put into place to minimise the distance and consequence of a fall as far as is reasonably practicable. Otherwise where it is not reasonably practicable to minimise the distance, then measures must be taken to minimise the consequence of a fall.
In practice, this means that the fall distance into a safety net must be as little as is reasonably practicable which will usually be the underside of the structure being worked on, as the greater the fall distance into a net the greater the likelihood of injury.
All safety nets used for fall arrest must be subjected to an annual test of the energy absorption capacity of the net. When new, a safety net will normally be supplied with three test meshes loosely attached to the safety net. At no more than 12 month periods a test mesh will be taken off and tested. Where the test mesh exceeds the minimum energy absorption capacity stated by the manufacturer, then the nets may remain in service for a further period not exceeding 12 months. Where the energy absorption capacity falls below the level stated by the manufacturer, then the net must be removed from service and destroyed.
The test house will produce written evidence of the results of the test, which must be kept by the netting contractor until the following years test results are available. It is, however, good practice to keep all safety net test mesh results throughout the life of each net. It is also good practice for the test house to issue tags or labels which should be attached close to the manufacturers label to help confirm this information on site.
To check whether the annual absorption capacity test has been carried out you can do the following:-
- Ask the netting contractor to supply the written history of a safety net.
- Look at the date of manufacture of the net, then record how many test meshes remain on the net.
For example a net manufactured in January 2005 should have two test meshes remaining by February 2006, one test mesh by February 2007 and so on. Whilst this will not confirm that the net has passed its annual energy absorption test it is a simple indicator that the netting contractor has a system in place for ensuring the test samples are removed for test.
Some safety net manufacturers issue tags which can be attached to the safety nets to confirm that the annual inspection has been carried out, but at the present time it is not a requirement for this to be attached to the safety net.
The riggers aim will always be to rig a safety net with no gaps between the net edge and the structure to which it is attached, however, a maximum permissible gap should be limited to 100mm wherever practical. It may not always be possible to achieve this in some circumstances i.e. lacing around columns, service pipes etc. and in these exceptional circumstances gaps up to 225mm are allowed.
The maximum centres for attachment of a fall arrest safety net is 2.5m when rope ties are used. It must be noted that other proprietary attachment devices may require closer attachment points and the manufacturers recommendations must always be followed.
The European Standard refers to a chart based upon the trajectory of the falling body, however, industry best practice is to rig the whole area. If this is not possible, then the net should extend a minimum of 3m.
- Where safety nets are rigged so that the fall distance is less than 1m, the safety nets must extend a minimum of 2m beyond the leading edge where operatives are working.
- Where safety nets are rigged so that the fall distance is less than 3m, the safety net must extend a minimum of 2.5m beyond the leading edge where operatives are working.
- Where safety nets are rigged so that the fall distance is less than 6m, the safety net must extend a minimum of 3.0m beyond the leading edge where operatives are working.
- If the working area is inclined by more than 20 degrees, then there must always be 3m minimum beyond the leading edge.
Fall arrest safety nets should be inspected by a competent person during the rigging process, and at handover stage to a contractor who is to work above the nets.
- The user should carry out a visual inspection before commencing work above a rigged safety net system.
- It is good practice for nets to be returned to the riggers premises for a formal inspection after each contract.
- Fall arrest safety nets should have a further inspection by a competent person every 7 days after handover if they continue to be worked over.
- Or following a period of adverse weather.
- Mesh: has to be formed (either knotted or knotless) in 100mm or 60mm size. It can be either diamond or square orientation.
- Border rope: the safety net must have a full and CONTINUOUS (spliced joint), with a minimum breaking strength of 30kN.
- Identification label: every net must have an ID label with the date of manufacture, net system and class, net size and reference to the product standard (BSEN 1263-1:2002)
- Unique serial number: every net must have a unique number to allow the net to be traced.
UV test meshes: each new net must have removable test meshes with their own serial number traceable to that particular net. Each year a mesh is removed and tested.
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