Fall arrest system:Fall Clearance Calculation

Fall arrest system :Fall Clearance Calculation

Fall Clearance calculation is used in fall arrest system which is preventing worker fall from above and to hit the ground. By this calculation its determine the minimum clearance distance needed below the worker to arrest a fall safely. This is a important component of a fall Protection plan.

Why is Fall Clearance Calculation needed?

1. Preventing Ground Impact: It is make sure the worker does not hit the ground or any other floor or ground surface during fall.
2. System Design: It is make sure the fall arrest system is properly designed, measuring length of lanyard,deceleration distance, harness stretch, and other factors.
3. Compliance with Standards: This calculation helps the organizations follow to safety regulations stated by indian and international standards.
4. Workers Safety: It is reduced the risk of injury or fatality in the event of fall of the workers.
5. Hazard Identification: It is help in identifies potential hazards related to fall clearance while making risk assessment.

Source of Formula

This formula comes from indian and international standards, including guidelines for fall arrest systems.

Indian Standards:

• IS 3521:1999: Industrial Safety belts and harnesses- Specification.
• IS 3764:1992: Code of Safety for Excavation work.( Required in some fall Scenarios like trench work.)

International Standards:

• OSHA( Occupational Safety and Health Administration): 29 CFR 1926.502(d) outline personal fall arrest system criteria.
• ANSI Z359.1: Safety requirements for fall arrest systems, sub systems, and components.
• EN 363: European standards for fall arrest systems.
• ISO 10333-4: Fall arrest systems performance and design.

Fall Clearance Calculation

The Fall clearance distance can be calculated as:

Formula:

Total Fall Clearance=Lanyard Length + Deceleration Distance + Height of Worker + Safety Margin

Components:

1. Lanyard Length: Maximum Length of the extended lanyard.
2. Deceleration Distance: Shock Absorber extended distance ( normally upto 1.2 m)
3. Height of Worker: Measure from the worker’s D-ring on the harness to their feet.
4. Safety Margin: Add Additional distance of 1 m for safety purpose.

Example

A worker name Rohan installing light at the 2nd floor of outer wall and his full body harness (FBH) attached with fall arrest system while working on platform which is 6 meters above the ground.

• The Lanyard length is 2 meters.
• The deceleration distance (shock absorber) is 1.2 meters
• Rohan height is 1.8 meters.
• A safety Margin is 1 meter.

Calculation:

Total Fall Clearance(TFC)=Lanyard Length + Deceleration Distance + Height of Worker + Safety Margin

TFC= 2 +1.2+1.8+1

TFC= 6 i.e. 6 meters