Window cleaners commonly use hand ascenders as their back-up device, or rope grab, while doing high rise window cleaning. You may have heard people say you shouldn’t do this and wondered why. Using your ascender as a back up isn’t forbidden in Petzl’s technical notice for their hand ascender (that’s the only one we checked). Nor is it specifically forbidden anywhere else that we could find. Many window cleaners have used jumars as their rope grab for years without a problem. So, what’s the deal?
The reason it’s a bad idea is that it’s not what the device is designed to do, and it’s likely to fail in case of a fall. Why take our word for it? Have a look at the testing we performed..
The Test Setup
We wanted to test hand ascenders in a real fall, so we went to Safety One Training. They recently put together an extensive testing area and offered to let us do some drop tests.
For the test, we used a 2′ Sterling Marathon Lanyard. We attached a 200 lbs weight to our back-up rope with the lanyard, some SMC carabiners, and a Petzl Ascension hand ascender. We performed two drops on the hand ascender: 1) Factor One (2′ Fall); 2) Factor Two (4′ Fall).
This setup replicates what we’ve seen in many photos and videos for high rise cleaners. We’ve seen lots of guys using their jumar (or other hand ascenders) as a back-up device and pushing it down as far as possible, creating a factor two fall. There are a variety of lanyards in use in these situations, but we think our test with the 4′ fall is representative of many of the cases we’ve seen.
Test One: 2′ Factor One Fall
We dropped our 200 lbs weight two feet, and the hand ascender performed surprisingly well. We generated just over 1,400 lbf, but the device held with no significant damage to the rope. The device itself was slightly bent, but still functioning. 1,400 lbf is within ANSI limits so long as it’s on the back D Ring of a proper harness (though, this would be unacceptable on a front D Ring, or worse, a sit harness).
Bottom line: After this fall, you’d still be in a position to rescue yourself and descend on your back-up line.
Test Two: 4′ Factor Two Fall
This test ended as we expected. It illustrates the reason why you shouldn’t be using a hand ascender as your backup device. The ascender breaks the sheath of the rope and slides down. In our test, it only stopped because we had a stopper knot at the bottom of the rope that made the sheath bunch up. It is likely that without that knot, the test weight would have fallen straight to the ground.
Bottom line: This test would likely have resulted in a fatal fall. If you were lucky enough to stop and were miraculously uninjured, you wouldn’t be able to descend on your rope to safety. That means that you wouldn’t be able to self-rescue and would need an assisted rescue.
Why Did This Happen?
Ascenders have aggressive teeth and clamp down on the rope to stop. With enough force, they are aggressive enough to cut through the sheath of your rope. The sheath of the rope is not connected to the core in most ropes (PMI Extreme Pro being a notable exception). As soon as the sheath is cut, it can slide right off the core.
I’ll Minimize My Fall Distance
You might be saying to yourself, “I’ve used an ascender for years without a problem. I’ll just make sure to keep it high and avoid a long fall.”
A few thoughts:
- Most window cleaning photos we see show factor 2 falls.
- Ascenders will wear out your rope faster because of their aggressive teeth.
- If OSHA catches you using an ascender as your back-up, there will be issues.
- There are a lot of great back-up devices on the market that work much better than ascenders.
So, please don’t use your ascender as a back-up. It’s a bad idea.
Thanks to Safety One for helping us perform this test. Let us know what other tests you’d like to see!