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The Guardian Fall Team Blog

Every day, hundreds of thousands of workers rely on their fall protection gear to keep them safe. In numbers probably uncountable, these workers constantly clip and unclip, tie and untie, and snap and unsnap themselves from anchors day in and day out, most likely without giving much thought to the engineering that went into their fall protection gear other than, “This thing better not break if I go over the edge.” At least that’s what I would be thinking.

With that in mind, it’s probably worth a trip down ANSI Lane (what, you’ve never heard of ANSI Lane?) to get a better appreciation of what kind of performance standards the ubiquitous snap hook must meet to be considered Z359.12-2009 compliant. I’d be willing to bet after you finish reading this and learn what is expected of these seemingly simple devices, you’ll never be able to look at a snap hook the same way again. I can’t.

Shut that gate, and keep it shut!

First, let’s talk about functionality. ANSI specifies in Z359.12-2009 ( that a snap hook must be self-closing and self-locking, meaning that closed is its normal state and that it must take “…at least two consecutive deliberate actions…” to open it. The operative word here is “consecutive.” Requiring two consecutive actions indicates that the first action is actually a locking mechanism for the second.

On a common snap hook, the lock is accomplished by a lever on the back of the hook that must first be depressed before the main gate can swing in and allow the hook to accept the anchor. The obvious intention of this is to prevent unintentional opening, or “roll out” as it’s called in Fall Protection jargon. It also means that unfortunately, at some time in the past, a standard single-action snap hook failed, likely resulting in an injury.

ISO Snap Hook Drawing

Try to break it, I dare you…

Once the basic functionality requirement is met, ANSI then demands snap hooks be tested to some pretty impressive standards. The first test requires that the hook withstand a load of 5,000 lbs. in the direction of normal usage, all without breaking or deforming to the point the gate will open. Think about that for a second. That little hook you connect to an anchor can hold the weight of a Ford F150 with a driver and passenger!

But ANSI isn’t done yet. Remember the self-locking gate? Well, they want to make sure it stays closed, so they require that the gate withstands a direct force of 3,600 lbs. without the gate separating from the snap hook body more than 1/8”. In car terms, that’s a Toyota Camry standing on your snap hook gate without it moving more than 1/8”. And just for fun it seems, they also want your Camry to stand on the side of the gate and it still not move more than 1/8” . I don’t know about you, but I suddenly have a lot of confidence in that quiet little snap hook, or maybe I’m just easily impressed.

Use It, Don’t Abuse It

Just because a snap hook is designed and tested to be extremely durable as well as self-closing and self-locking doesn’t mean you can be careless with it; you must still avoid using the snap hook in a manner for which it was not designed. The following are some examples of incompatible snap hook connections (or how not to use a snap hook):

  • DON'T connect two or more snap hooks to each other
  • DON'T use two connectors to same D-Ring
  • DON'T use in an incompatible or irregular application (e.g. undersized anchor)
  • DON'T connect your snap hook directly to webbing, lanyard or horizontal lifeline
  • DON'T use in an application that puts load directly on the gate

The More You Know

Let’s face it, no matter how strong a manufacturer can make a snap hook, you still must use your noggin when using it, else you risk using your noggin to stop a fall; which from what I have heard can be bad, really bad – as in notify your next of kin bad. Don’t be that guy or gal. If you have any questions about where/how to use it on the job, grab the closest Competent Person and have them assess the situation. Better yet, get yourself to a Competent Person class so that you can be the one people look to. Knowledge is infectious, kind of like laughter or that skin rash you had in summer camp…

Well, you’ve made it, 736 words on a piece of equipment you thought you knew, or maybe felt you knew enough about. And now that you really do know more about the not-so-lowly snap hook, I’d be willing to bet the next time you handle yours, you’ll be just a little more careful with it. Take the time to give it a good look; make sure the gate locks like it should and that there is no rust or scale on it, or any burrs that could cut any webbing. You can thank me later. For now, just be safe up there.