In circumstances where a person is ascending a vertical ladder, using a full body harness/twin tail lanyard fall arrest system and using the ladder rungs as anchor points, do the ladder rungs have to be rated the same as other designated anchor points in accordance with AS/NZS 1891.4 2009 Industrial fall-arrest systems and devices; selection, use and maintenance (i.e.: 12 Kn for limited free fall-arrest)?
As a starting point, compliance with a standard (such as AS/NZS 1891.4 2009 as you have mentioned) is only mandatory if it is stated as being so in the WHS legislation. The AS/NZS 1891.4 2009 is actually not a mandatory standard under the legislation, and is not referred to under the WHS Regulations.
However, the Code of Practice: Managing the risk of falls in workplaces, does include reference to the AS/NZS 1891.4 2009 series and ‘relevant Australian/New Zealand Standards’.
The anchorage points section states: “Each anchorage point should comply with the requirements in AS/NZS 1891.4 Industrial fall-arrest systems and devices selection, use and maintenance.”
Under the restraint technique section, it also states that a restraint technique is suitable for use where “the restraint system conforms with AS/NZS 1891 Industrial fall-arrest systems and devices series.” It further makes clear that temporary systems should comply with the AS/NZS 1891 series of standards. We recommend reading the Code, located at the Safe Work Australia website.
You should be aware that while compliance with a standard that is referenced in a code of practice is not mandatory, a Court may have regard to it in determining what is reasonably practicable in the circumstances. The code should be followed unless following another method provides an equivalent or higher standard of work health and safety.
Therefore, it is our view that the fall arrest systems being used with the anchors should provide energy absorbers, or other means, that limit the peak load on the harness connection and thus anchor during a fall to 6kN, as per the AS/NZS 1891 suite of standards.