The ABCs of Personal Fall Arrest Systems
All workers exposed to falls should be trained by a competent person to recognize fall hazards and to be familiar with available control methods and equipment.
- By Hugh Smith
- Jul 01, 2015
Three key components of a Personal Fall Arrest System (PFAS) must be properly in place to provide maximum worker protection. None may be able to do the job alone. However, in combination, they form the ABCs of fall protection and are vitally important to job site safety.
A is for Anchorage/Anchorage Connector
Anchorage connectors (tie-off points) secure a connecting device to an anchorage. Anchorage selection is critical because, should a fall occur, the worker will be suspended from that anchorage—with his or her life depending on its strength. The anchorage should be easily accessible, located a safe distance above any lower obstacles, and capable of supporting 5,000 pounds per worker.
Note the distinction between an anchorage and an anchorage connector. An anchorage, for example, could be an I-beam. An anchorage connector might be a cross-arm strap, or choker, wrapped around the beam to permit attachment.
Active Fall Protection Systems
If perimeter platforms cannot be used, install active systems and require workers to don harnesses and connect to an overhead system. Active fall protection systems include fixed-point anchors, horizontal lifelines, and conventional beam and trolley systems—each attached to the existing overhead structure.
According to OSHA, fall protection systems must be "capable of supporting at least 5,000 lb (22 kN) per employee attached" or be part of a complete system designed by a qualified person that maintains a safety factor of at least two. Thus, any active fall protection system should be designed by a qualified and experienced person and include an analysis of the supporting structure.
Passive Fall Protection Systems
Considering OSHA's Hierarchy of Fall Protection Controls, where fall hazards cannot be engineered out, the best option is to utilize a passive fall protection system. These require no special equipment or active worker participation. Such systems (e.g., catch platforms) can be installed around the perimeter of the work area. They should be of adequate width and include an exterior handrail to catch a worker. They also can serve as work platforms.
Fixed Point Anchors (FPAs)
The easiest active system to integrate may be a series of FPAs over the work area. Each FPA consists of a certified anchor point to the existing overhead structure, from which a shock-absorbing lanyard or self-retracting lifeline (SRL) is supported. Workers work centrally under each FPA, within an approximately 15-degree range. They transition to adjacent FPAs as work progresses, maintaining 100 percent connectivity. If a limited number of workers are making frequent transitions to adjacent FPAs, this system may hinder productivity. FPAs also require significant structural anchoring. Therefore, consider a mobile anchorage point.
Mobile Anchorage Points
Horizontal lifelines (HLLs) and conventional beam-and-trolley monorail systems attached to the overhead structure offer uninterrupted protection while working. Either system can be designed for multiple workers. Both should be equipped with SRLs and be located centrally over the work area to avoid swing falls. Consider parallel systems for multiple workers.
Simple engineered HLL systems are available as kits, but these are generally limited to single-span applications. More sophisticated HLLs incorporate a pass-through feature, whereby a proprietary shuttle can automatically pass through intermediate lifeline support points. These systems may be multi-span; they can reduce HLL deflection and costs. HLLs should include a tension-indicating mechanism to properly tune the system for reliable performance. Also, an HLL may require an in-line shock absorber to reduce forces to the supporting structure.
In general, HLLs are the economical alternative to higher-priced beam-and-trolley systems. However, some structures cannot easily support the high anchor forces that accompany HLLs. In these cases, beam-and-trolley systems, which show negligible deflection and ensure smooth-running performance, may have the advantage.
Finally, all workers exposed to falls should be trained by a competent person to recognize fall hazards and to be familiar with available control methods and equipment.
B is for Body Wear
A full-body harness includes hardware, webbing, and pads, each with specific functions.
Hardware must be sturdy and easy to attach to connecting devices. Avoid oversized, excessively small, or awkward components or otherwise incompatible hardware. Watch for unintentional disconnection from components ("roll-out" or "burst-out"). Steer clear of hardware with sharp edges that can cut harness webbing or workers.
Construction is important in friction buckles. If not spring-loaded, they can loosen once the harness has been adjusted for fit. Beware of exposed springs, especially on friction buckles; such springs can become disabled or dislocated.
Webbing varies drastically among brands. Select sturdy webbing with tightly woven yarn that slides through hardware without snagging. If webbing is cut, burned, frayed, etc., remove the harness from service.
Webbing should meet the ANSI standard of 5,000 pounds (22 kN) tensile strength, endure traditional abrasion tests without fraying and puckering, and resist natural weather effects. In a harsh chemical environment, it must resist toxic chemical fumes and splashes. Stitching should be strong enough not to rip away during a fall.
Padding should be pliable and easy to adjust, to ensure a comfortable fit. Padding also must withstand harsh weather and maintain its shape. Because padding can become brittle in cold weather, select padding that features breathable fabric and durable construction.
Critical Components, Critical Fit
A comfortable fit is crucial to compliance—as is a snug fit with chest, back D-ring, and leg straps.
The placement and connection of the chest strap and back D-ring are critical for proper harness fit and safety. Chest straps must be positioned in the mid-chest area. Back D-rings must be located in the middle of the back between the shoulder blades. Both must be tightened for a snug fit.
Chest straps should be easy to adjust and able to withstand fall forces without tearing or breaking. If improperly fastened, a strap can slide up around a worker’s neck in a fall. Metal chest hardware is the preferred choice for safety; it should consistently meet 4,000 pounds (17.8 kN) of "pull force" when tested.
Size harnesses appropriately to ensure compliance. Universal sizing doesn't necessarily fit all work comfortably. Research various styles and designs to accommodate each individual employee's shape, size, and specific application. Employees more readily (and properly) wear a comfortable harness that's easy to adapt to lanyards and other connecting devices. Better harness selection means improved compliance and safety.
C is for Connecting Device
The critical link between harnesses and anchorage points is the connecting device.
A lanyard is a flexible line securing a full-body harness to an anchorage point. There are two basic categories: non-shock-absorbing and shock-absorbing. The more common and safer is the shock-absorbing variety, which comprises the majority of all lanyards sold today. Do not use non-shock-absorbing lanyards for fall arrest.
Shock-absorbing lanyards provide deceleration distance during a fall, reducing fall arresting forces by 65-80 percent below the threshold of injury, as specified by OSHA and recommended by ANSI. The most reliable include a special shock-absorbing inner core material surrounded by a heavy-duty tubular outer jacket that doubles as a backup web lanyard. Per OSHA, all lanyards must have double-action, self-closing, self-locking snap hooks to reduce the possibility of roll-out.
Shock absorber packs can be attached to, or built into, non-shock-absorbing lanyards to provide shock-absorbing capability. During a fall, an inner core smoothly expands to reduce fall arrest forces. Some feature a backup safety strap.
Self-retracting lifelines (SRLs, fall limiters, personal fall limiters, yo-yos, seatbelts, blocks, etc.) are alternative connecting devices.
While traditional 6-foot shock-absorbing lanyards allow for up to 6 feet (1.8 meters) of free-fall distance prior to activating, self-retracting lifelines require less than 2 feet to arrest free falls. With their shorter activation and arresting distances, self-retracting lifelines reduce the risk of workers' hitting the ground or impacting obstructions at lower levels. They also allow for easier rescue.
Self-retracting lifelines enable greater horizontal and vertical mobility than standard 6-foot shock-absorbing lanyards. Self-retracting lifelines are available with working capacities from 6 feet (1.8 meters) to 175 feet (53 meters).
Whenever possible, when using a lanyard or lifeline, position the anchorage point directly overhead to protect the worker from a swing fall or pendulum effect during a fall.
While no single component is subjected to the total fall force, connecting devices comprise only one strength member (e.g., webbing, rope, steel cable). Substandard design, poor-quality workmanship, excessive exposure to UV light or to chemicals, physical damage, improper storage, or inadequate inspection can lead to device failure.
Evaluate the following when choosing a connecting device:
- Type of work and specific worksite conditions, including the presence of moisture, dirt, oil, grease, acids, electrical hazards, and ambient temperature.
- Potential fall distance—usually greater than anticipated. Consider the length of the connecting device, the length of elongation during deceleration, and worker height, then add a safety factor.
- Compatibility of system components. A personal fall arrest system should be designed and tested as a complete system because components from different manufacturers may not be interchangeable or compatible; this can cause roll-out.
- Product quality. While OSHA regulations are U.S. law and are enforced by a federal agency, ANSI standards are self-enforced, with no inspectors. Do not take stated performance per ANSI guidelines for granted.
The consequences of failure of a personal fall arrest system can be severe and far-reaching: worker injury or fatality, lawsuits, higher insurance and workers' compensation premiums, and lost time from the job. The best fall protection cultures of safety begin with the ABCs.
This article originally appeared in the July 2015 issue of Occupational Health & Safety.