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The Guardian Fall Team Blog

If asked to describe two things that are compatible, most people wouldn’t have much difficulty. We would probably hear a variety of responses involving such well suited pairs as salt and pepper, a screw and a screwdriver, or gasoline and an engine; the possibilities are endless.

To be compatible, two objects need to work together, at the very least without diminishing the functionality of each object independent from the other. Most frequently though, their functionality is in some way enhanced by using them in tandem.

This same exercise can be applied towards incompatibility, and similarly, there are a multitude of examples we can use to illustrate the concept. We might hear about anything ranging from oil and water, to the common cliché of a round peg in a square hole. These things don’t mix, don’t fit, and ultimately become less functional when used in combination with each other.

Understanding what is and isn’t compatible is a basic skill that helps us in many aspects of our lives, but in the world of fall protection it takes on a whole new level of importance. Because, when it comes to working at heights, being able to recognize, apply, and differentiate between compatible and incompatible connections not only can help a worker do their job, it can save their life.

Often times, when working with fall protection equipment, one’s focus is drawn primarily to each individual component of the personal fall arrest system (PFAS) needed for the given job. If the harness, lanyard or self-retracting lifeline, and anchorage connector are all present, then it might be assumed the job can be done safely and effectively.

But not so fast.

Unless each component of the PFAS is determined to be compatible with the others by a Competent Person, and each component is connected to the others in a compatible fashion, a significant risk still exists for injury to be incurred.

So, the question becomes, what does an incompatible connection look like in a PFAS? It’s not always an easy question to answer, simply because of the fact that there are so many different possible combinations of equipment (another reason why Competent Person selection of equipment is so important). If, for example, a snap hook won’t attach to a given anchorage connector due to a substantial size difference, then the incompatibility of the two devices is simple to determine. If the same snap hook is able to be attached to a different anchorage connector, however, does that automatically mean the two devices are compatible? Not necessarily. Simply being able to connect PFAS equipment doesn’t guarantee compatibility. The risk of “roll-out,” which is the risk of accidental disengagement of a connector, must always be considered prior to work beginning.

Roll-out occurs when a connector, such as a snap hook or carabiner, is improperly sized for its attachment point; not in that it is too small, but in that the potential exists for it to be maneuvered so the attachment point places a load on the connector gate and opening mechanism. So, if a significant enough force is applied to the PFAS in a particular direction, the attachment point could cause the connector gate to open and disengage, resulting in a fall. It is critical that the Competent Person account for the risk of roll-out during their selection of equipment, and that the Authorized Person inspect for risk of roll-out prior to each use.

There are many other types of incompatible connections as well. In their fall protection regulations, the Occupational Safety and Health Administration (OSHA) lists a number of them, including the connection of snap hooks to each other, directly to webbing or rope, to a D-ring to which another connector is attached, and directly to a horizontal lifeline. OSHA does allow for the stipulation that connectors may be used in prohibited ways if specifically designed for such use by the manufacturer. The onus then, however, is placed on the manufacturer to prove their equipment is safe for such use, so unless a job absolutely requires for such a connection and the manufacturer guarantees such use is acceptable, the safest action is always avoidance.

When compatible connections are made between individual components of a PFAS, the functionality of each component is enhanced; their potential transforms from inactive to active, and they become capable of saving someone’s life. But, if these components are connected in an incompatible fashion, their active potential becomes dangerous, creating the risk of harm from a fall where it didn’t previously exist.

Always remember, when it comes to fall protection, oil and water don’t mix.