Fall Arrest System
The design principle will protect end-users from serious injury, as it greatly reduces the effects of a fall. The end-user can reach a point where a fall can occur.
To allow this design principle to function correctly, a minimum fall clearance distance of 6m is required. This is needed to incorporate shock absorbing lanyard deployment and cable deflection, along with size (height) of end-users. A correctly designed system will arrest an end-user in the event of a fall (after 2m) preventing the end-user from hitting the deck.
As indicated, ridge systems are installed to the ridge line of a roof. They can be installed slightly off centre (to the left or right) to allow for sky lights, chimneys etc.
Ridge systems do not run to the end of the building. They run on either side and should stop 2m from each edge of the roof end. Due to this design principle a pendulum swing hazard occurs. To counter this, 4No single point anchors (anti-pendulum posts) are required to be installed (1No in each corner) thus alleviating this hazard with the correct use of the PPE supplied.
Fall Restraint System
This design principle stops the end-user from reaching any position where a fall can occur, still providing full and unrestricted access to all areas of the roof as required (gutters, fans, roof lights etc.) and is the recommended choice of system.
The correct use of Personal Protection Equipment (PPE) i.e. Harnesses, Lanyards etc, is critical to this design principal working correctly. Loads exerted on restraint only systems are significantly less than those required on fall arrest systems.
Systems fitted to the perimeter of a roof are better for wider roofs, and are easier for end-users to operate.