Understanding the different types of carabiner and connector along with their use cases.
While roof anchors are the single most common component of a building’s fall protection system, carabiners would be the most common item used by workers to connect to one.
Carabiners come in a variety of shapes and sizes. And they can be used for all manner activities from keeping your keys together to competitive sports climbing to fall protection.
It’s the latter use we are going to look at here. What are the different types of carabiners available, and how do you select the best one to use? It is important that workers are using the most appropriate type of carabiner for the job being done.
Carabiner or karabiner?
There are two commonly used spellings for these types of connectors – karabiner and carabiner.
Both, really, are correct – there are no wrong answers.
In practice, however, most people tend to lean towards “carabiner”, while in AS/NZS 1891.4:2025 they use “karabiner” as that is what was in previous versions of the standard and is more in line with the Germanic etymology of the word.
In this piece, we are going to stick with the former.
Carabiner strength requirements
As they form an important part of a fall protection system, all carabiners used must meet certain levels of strength to ensure they do not fail in the event a worker does fall.
The requirements for the strength required of carabiners in fall protection systems are outlined in AS/NZS 1891.4:2025 s 6.2.
A carabiner’s gate must be able to resist a load of at least 6kN across the gate’s face and sides. In the main direction of loading, (longitudinally) the carabiner must support at least 22.2kN loads.
In addition, the gate of a carabiner must have a mechanism that automatically locks and secures it.
What are the different types of carabiner?
As with all things height safety and fall protection, carabiners come in a range of types and sizes and are designed to suit a variety of different purposes.
Not every carabiner is adequate to use as part of a fall protection. So, care must be taken from the outset to ensure that whatever carabiner you have is at least one where the gate can be locked. Non-locking carabiners, like the type used in sport climbing or to connect tool tethers, cannot be used as part of a fall protection system.
Screw-gate carabiners are carabiners where the gate is locked manually via a screw-thread. These have been the most basic form of carabiner for a long time as they are cheap to manufacture and very easy to use.
Double-action carabiners require two movements to unlock the gate. Most commonly, the gate is rotated before it can be pushed open. When released, the gate should automatically close again.
Triple-action carabiners require, you guessed it, three movements to unlock the gate. Typically, the gate must be lifted slightly, then twisted, then pushed to open it.
There are even carabiners on the market that require a quadruple-action to unlock. This can be where the gate is twisted, lifted, twisted again before it is pushed open.
Types of hooks
There are two main types of hooks that are found when working in fall protection and height safety. Snap hooks and scaffold hooks.
Hooks are often found on the end of single and twin-tail lanyards, a self-retracting lifeline or at the end of a rope line. The main difference between a snap hook and a scaffolding hook is the size of the eye.
Snap hooks have a smaller gate and connecting eye. These are generally used for connecting to roof anchor points, vertical and horizontal line shuttles, and the like. Scaffold hooks have a much larger gate and connecting eye so that they can be used on, surprise, scaffolding and other larger-sized objects.
Like carabiners, snap and scaffold hooks need to meet certain requirements for use in fall protection systems and also service different use cases. This is also defined in AS/NZS 1891.4 s 6.2.
All hooks must be self-closing and self-locking with the gate secured by means of a latch mechanism. This means they require at least two distinct motions to unlock and open (similar to a double-action carabiner). The gate must be able to withstand at least a 6kN load across the face and the sides.
Choosing the right connector for the job
When choosing a connector, like any tool or piece of PPE, it is important to consider the work being done, the environment it is being done in and, for fall protection, the type of system being used.
Best practice, when it comes to selecting carabiners, is to use triple-action ones. These can be operated with one hand, while also providing suitable protection against accidental opening. Although it is unlikely, a double-action carabiner could be opened by having it pressed against a structure or other object.
It is not recommended to use screw-gate carabiners in fall protection systems. Movement by the user across the work area can vibrate the carabiner, which results in the screw-gate unrolling and leaving the gate open.
The Working at Height Association has put together a quick-reference table that can be referred to when considering which type of connector to use.
| Connector type | Opening mechanism | Locking actions | Level of compliance | Recommended use |
|---|---|---|---|---|
| Screw-gate carabiner | Manual screw | 1 | Limited | Static applications under close supervision |
| Double-action carabiner | Twist, push | 2 | Yes | General fall arrest |
| Triple-action carabiner | List, twist, push | 3 | Preferred | Rope access, utilities |
| Quad-action carabiner | Multi-step sequence | 4 | High-risk tasks | Towers, live plant |
| Double-action hook | Palm and fingers | 2 | Minimum compliance | General lanyard attachment |
| Triple-action hook | Lock, twist, open | 3 | Best practice | Construction, boom lists |
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