Fall-arrest systems, incorporating a lanyard, should be installed so that the maximum distance a person would free fall before the fall-arrest system takes effect is two metres. 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 fully deploy. To work out whether there is enough distance available, you should take into account:

  1. the worker’s height
  2. the height and position of the anchorage point
  3. the length of the lanyard
  4. any slack in the horizontal life line
  5. any stretching of the lanyard or horizontal life line when extended by a fall
  6. the length of the energy absorber when extended by a fall.

 

The calculation for maximum fall distance is:

  • Original length of lanyard         = 2.0m
  • Max length of shock absorber  = 1.75m
  • Harness stretch                          = 0.30m
  • Height of persons                      = 1.8m
  • Clearance from ground            = 1.0m
  • TOTAL FALL DISTANCE        = 6.85m

SO YOU CANNOT WORK IN FALL ARREST ON A SINGLE STORY DWELLING OR ANYWHERE BELOW 6.85M

MAINTAIN MINIMUM OF SLACK IN FALL-ARREST LANYARD

There should be a minimum of slack in the fall-arrest lanyard between the user and the attachment. The anchorage point should be as high as the equipment permits. Avoid 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 lanyard snagging on obstructions.