BS8513 - slipping by in the shadows

The long-standing EN product standards for fall arrest lanyards (EN354 for the 'lanyard' and EN355 for the energy absorbing element) are well-known by everyone working with fall arrest. Some of us happily agree they're a little vague to interpret, mostly because of the way the load-bearing (but not energy-absorbing) concept of a lanyard is covered by one standard, and the energy absorber by another. It means a commercial product has two numbers printed on it, but it's intentional - as there are many cases where you want a lanyard without an energy absorber. Indeed, EN354 is designed to be so vague that it can even apply to swivels and chain links.

There is however an 'issue' with EN355, namely that as with all other EU-harmonised fall protection standards, it assumes a user bodyweight of no more than 100kg. A manufacturer may want to design a product for use by someone over that bodyweight, but EN355 can't certify it for more than 100kg as under clause 4.4 the test mass has to be always the same. EN354 doesn't actually care too much about user weight, as it's only the energy absorber which would react differently in a fall.

So, if you're too heavy, you may rip to the very end of the energy absorber, and potentially suffer an injury. If you're too light then you may be arrested too quickly, and also suffer an injury. The generally-accepted working range for an EN354/355 lanyard is 80kg to 100kg. "Outside that, you cannot use them. Period."

Well.. not exactly. It's true that an overweight user could run to the end of the absorber, but only if they fall in an unbelievably extreme way. Manufacturers always design the absorber to have extra capacity, so even a 100kg person falling in factor 2.0 would not expect to get anywhere near the end. A heavier person would get closer, but is still unlikely to hit the buffers - and besides, a FF2.0 event is hardly ever going to happen if the worker is using their equipment in accordance with good practice.

If you drive your car into a wall at 120mph, the airbag may not deploy in time. That's not an airbag fault.

The good thing about this "working outside the paperwork" system is that although the lanyard may only be "rated" for 100kg, if you weigh a bit more you will still only feel the agreed safe 6kN peak force during arrest. You'll travel a bit further, but 600kg is the limit. That's important, as most of the other stuff you're using, from the harness to the karabiners, eyebolts, wire systems etc. all assume that figure is as high as forces can get. The actual value of 6kN was chosen almost at random - military tests post-WW2 showed that 12kN was the point of survival, and so the EU regs simply halved it. In the USA, they use 8kN and there's no evidence they experience more injuries as a result of their choice.

So, background lesson aside, what's BS8513? Well, it's a draft British Standard for twin-tail fall arrest lanyards, being written by PH/5 and available for comment online at the BSI Drafts website. Most of it is a copy of EN354/355, but it has one crucial difference, which I am not at all happy with. It allows 8kN.

Rather than using the EN logic of "your body will fit our range", BS8513 defines three new types of lanyard, based on user weight:-

• For users under 80kg, the arrest force must not exceed 5kN
• For users 80kg to 100kg, the arrest force must not exceed 6kN (equivalent to EN355)
• For users 100kg to 140kg, the arrest force must not exceed 8kN

Sounds sensible - but think about it for a minute.

• 'Users under 80kg' is what it says it is. A user of 20kg must be able to use this type of lanyard, and that's simply impossible to engineer, especially as the standard also demands that below 1.5kN the absorber cannot deploy. There has to be a lower limit, even if it's a small one. PH/5 clearly don't understand this.
  
• If I weigh 101kg, why should I be subjected to more force than if I weigh 99kg? Surely I'd prefer to fall an extra foot, at 6kN, than stop in the same place but with more energy applied to my internal organs?

Ahh, you say, but the USA system allows 8kN! Yes it does, but only on the back attachment point. They are almost religious in their affirmation that 8kN on a sternal attachment point is hideously unsafe. They should know - they've done the tests. The UK has not.

Aside from this question of "is it safe" - changing the limit to 8kN also means all the other stuff you're using has to change too. BS8513 even goes to the trouble of defining special types of connector for these heavyweight lanyards. Is a user actually going to know how to work like that? You've got to be kidding. Weighing yourself every morning to decide which lanyard to use? Not likely.

And what of EN354/355 lanyards? The EU regulations mean their sale cannot be restricted, so someone in the UK can buy and use them, even if they don't have BS8513 approval. Do you need to throw them away and buy new ones? Should workers now all be issued individual lanyards or be forced to diet?

BS8513 started off with good intentions, but there is a good reason why the EN standards are vague. By trying to fill in the details, they have created a monster.

What should they have done?

1. If they want weight ranges, then overlap them, so people will never be on the limit between two.
2. Forget 8kN entirely, and simply allow a longer drop distance for heavy users.

Will they?


...was that pork outside your window?....