A personal fall arrest system (PFAS) is a comprehensive setup designed to safely stop a worker from falling after a fall event has begun, preventing the person from hitting a lower level or obstruction. A functional PFAS is composed of three interconnected elements, often referred to as the “A-B-C”s: Anchorage, Body Support, and Connecting Devices. Each component must be compatible and properly utilized to manage the forces generated during a fall and ensure the worker’s safety.
The Foundation: Anchorage Points
The anchorage is the secure, fixed point to which the rest of the fall arrest system is attached. This component is the foundation of the entire setup, bearing the full force of a worker’s fall. It is generally recommended that the anchorage point be located directly above the worker to minimize the distance of a free fall and prevent a dangerous swing fall.
The connection point must meet specific strength criteria, requiring a minimum of 5,000 pounds per employee attached. Engineered anchor points may be used if installed under the supervision of a qualified person, provided the system maintains a safety factor of at least two. Anchorage points are classified as either permanent (e.g., concrete embedments) or temporary (e.g., cross-arm straps), but they must never be used to support or suspend platforms.
Body Support: The Full-Body Harness
The body support component is the full-body harness, the only acceptable device for fall arrest, designed to distribute fall forces across the strongest parts of the body. The harness uses straps that secure the individual around the shoulders, chest, pelvis, and thighs, reducing the risk of injury from concentrated force. Body belts are prohibited for fall arrest use because they focus fall forces onto the abdomen, which can lead to severe internal injuries.
Proper fit is essential for the harness to function correctly, requiring all straps to be snug but not restrictive to ensure the worker remains upright after a fall is arrested. The most important attachment point for fall arrest is the dorsal D-ring, located between the worker’s shoulder blades. This location correctly positions the body during the fall and subsequent suspension, aiding in both injury prevention and rescue operations. Other D-rings, such as those on the chest or hips, are reserved only for work positioning, travel restraint, or ladder climbing systems, and must not be used for fall arrest.
The Link: Connecting Devices
The connecting device is the physical link between the full-body harness and the anchorage point, serving to both allow movement and arrest a fall. This component is responsible for absorbing the energy generated during a fall to limit the force exerted on the worker’s body to a maximum of 1,800 pounds. The two primary types of connectors are lanyards and self-retracting lifelines, which differ significantly in their operation and fall distance management.
Lanyards
A standard lanyard is a flexible length of rope, webbing, or wire rope that connects the harness to the anchor. The most common type used for fall arrest is the energy-absorbing lanyard, which contains a deceleration device, often a pack of specially woven material that tears open upon impact. This tearing process dissipates the energy of the fall, effectively slowing the descent and reducing the arresting force on the worker.
Federal regulations mandate that the maximum distance a worker travels while the deceleration device is deployed cannot exceed 3.5 feet. This deceleration distance, combined with the lanyard’s original length, dictates the total distance required to stop the fall safely. Energy-absorbing lanyards are typically limited to a maximum free fall distance of six feet, which requires careful planning of the anchorage location.
Self-Retracting Lifelines (SRLs)
Self-retracting lifelines (SRLs), often compared to a vehicle’s seatbelt, operate with a spring-loaded spool that keeps the line taut during normal movement. If the worker accelerates suddenly, indicating a fall, an internal braking mechanism instantly locks the lifeline, arresting the fall almost immediately. This mechanism significantly reduces the free fall distance, often limiting it to less than two feet when anchored overhead.
SRLs are advantageous in situations with limited fall clearance because their rapid activation minimizes the overall stopping distance compared to energy-absorbing lanyards. The constant tension also eliminates slack in the line, which reduces the potential for trip hazards and minimizes the risk of a severe swing fall if anchored laterally.
Calculating Fall Clearance and System Performance
Total fall clearance is the vertical distance below the worker required to safely arrest a fall before impact. Calculating this clearance prevents the worker from “bottoming out” and striking a lower surface or object. The calculation is a summation of multiple factors, beginning with the free fall distance, which is the vertical distance traveled before the connecting device begins to engage and slow the fall.
This distance is then added to the maximum deceleration distance, which is limited to 3.5 feet for energy-absorbing lanyards. Additional distance must account for the potential stretch of the harness and a shift in the dorsal D-ring during the fall, typically adding about one foot. Finally, a safety factor, conventionally set at two feet, is added to account for variables like an improperly fitted harness. For a standard six-foot lanyard, the total clearance required often exceeds 17 feet.
Inspection and Maintenance
The integrity of a PFAS relies on rigorous inspection and maintenance practices. Workers must perform a thorough pre-use visual and tactile inspection of all equipment before each use. This daily check is to look for obvious signs of damage, such as cuts, fraying, pulled stitches, or chemical damage on the webbing, and distortion or corrosion on the metallic hardware like D-rings and snaphooks.
In addition to the daily user checks, the equipment must undergo a formal, documented periodic inspection by a competent person, at a minimum of once a year. Equipment must be immediately removed from service if it shows signs of damage or if it has been subjected to a fall arrest event, as these components are designed for a single use. Proper maintenance also includes cleaning the equipment with a mild solution of water and detergent and storing it in a cool, dry, dark place, away from excessive heat, sunlight, fumes, or corrosive elements to prevent material degradation.