Posted By Alan T I've seen this method used a few times usually for short duration work. When managed correctly it is safe although it does not strictly follow the hierarchy of risk control because prevention of the fall by a physical barrier should be used before PPE and remember you should also have in place a rescue procedure.

Posted By Stuart Nagle I have come across this too for working on the falt roof of portacabins for short duration works. My inital thoughs were sceptical, but on giving it further though I actually belive it is a good solution for short duration works where the workplace is not at a height where other measures must be taken. There is always the issue of falls, through slips and trips, and it would still be unpleasant and give a few bruises to come off a portacabin if working near the edge and being restained by a device. so the essence is to position centrally and have devices that do not permit persons to fall off the edge - e.g. restricted length inertia reel.... Stuart