Chemical, expansion, ground, temporary, permanent are all types of fall arrest anchor, but which one would you choose and on what basis would you make that choice? It can be a daunting task especially if there are external pressures from clients, principal contractors, designers and even your employees to get the project completed on time.

There are a few simple rules that should make life easier when choosing the correct type of fall arrest anchor.

Anchorages can be broken down into four main types; the first thing you have to do is consider the intermediate attachment equipment you will be using. Intermediate attachment is an all encompassing phrase used to describe the safety equipment that connects the user and their harness to the anchorage point.

It is this choice of equipment that needs to be taken into account as certain intermediate attachments require a higher standard of anchorage testing and certification. And subsequently your method statements and risk assessments will need to be more detailed and complex.

The main types:

Fall Arrest Temporary Anchors & Locations

This is a type of anchor that is used with Fall Arrest equipment, for example shock absorbing lanyards and inertia reels. “Temporary” means you can use it for that moment in time, it is temporary for you to use but it may be permanent to the structure. The most important aspect in choosing this type is that it has to withstand a dynamic force of 12kN which gives a safety factor of 2:1 as fall arrest equipment has to limit the arrest forces to 6kN. This type of anchor might include the steel structure of a building, such as a structural column or a girder. Selecting the appropriate suitability of anchors is usually a decision which is made based on experience and competence. However if there is any doubt you should consult your architects, chartered engineers, or other such competent person ensuring that you have written documentation to support this decision.

Anchor points should be chosen in consideration of the free fall distance required should the user fall. Where possible the fall arrest anchor should be above head height to minimise the fall distance required. Consideration should also be given when choosing the anchor location as to avoid the possibility of creating a pendulum swing fall.

Fall Arrest Permanent Anchors & Locations

This type of anchor is used with Fall Arrest equipment, as mentioned above. “Permanent” means an anchor that is designed to be nothing else but an anchor for fall arrest equipment; this includes any elements or components which are incorporated into the anchor point. For example, eye bolts, permanently installed wire or rail systems and dead weight anchors. The most important aspect of permanent anchors is that they must be installed, tested and certified to BS EN 795 by trained and competent people. That certificate must be attached to the permanent anchor and be legible. It is recommended that for class A1 anchors – e.g. eye bolts – that these are installed by a qualified competent person. Further advice on installation and periodic proof loading of class A1 anchor devices conforming to BS EN 795, which includes anchor devices designed to be secured to vertical, horizontal and inclined surfaces, e.g. walls, columns, and lintels can be found in BS7883. Also included in BS EN 795 are dead weight anchors – class E, anchors for use with horizontal flexible life lines – class – C, and slings – class

• Deadweight and counterbalance anchor systems

Consideration needs to be given to the cantilever and frictional effects of this type of anchor. It is important that attention is given to wet or icy conditions as this can significantly affect the frictional performance of the anchor. BS 8437:2005 recommends that the anchor should be checked ensuring that it does not move when subjected to a load of four times that which will be applied in a work positioning situation, it further says that users should also consider the possibility of rescue, which might involve the weight of two persons.

• Permanent horizontal flexible anchor lifeline

When installing a horizontal flexible anchor lifeline special consideration needs to be given to the deflection of the line when under fall arrest load, and particular attention needs to be given to the position of the anchor line supports when assessing the required free space below the user in case of a fall. Maximum distance between anchors, and the number of operatives attached to the anchor line must be strictly in accordance with the manufacturer’s instructions.

• Anchor Slings

Anchor slings can be made of textiles, steel wire rope, or chain. Textile anchor slings should have a minimum breaking strength of 22kN and the minimum strength of anchor slings made from wire rope or chain should be 15kN. Due to the weakening effect of looping anchor slings or lanyards through themselves – a miss configuration known as larks footing or choking – should be avoided, unless they are specifically designed to allow this, for example by provision of special loops along their length, or designed to a higher rating to make an allowance for the miss configuration e.g. wire slings rated to 24 kN or higher.

Adjustable Restraint Anchors

Restraint is a system of working that allows an operative to reach the leading edge or fall hazard and no further – if used correctly, thus preventing them from falling. Adjustable restraint allows the operative to set the restraint system to suit the task at that moment in time.

This is done by setting the distance from the anchor point to the fall hazard using a rope grab cam device which fixes the correct length of rope taking into account the length of connectors etc. This prevents the user going beyond the point at which they could fall. it’s “>It’s an ideal way of working for the roofing industry as the fall hazard changes almost on a minute by minute basis.

The anchor point for adjustable restraint must be able to with stand a dynamic force of 12kN because adjustable restraints must have a fall arrest back-up (EN353-2), in the event of the system being misused. To reduce the likelihood of this type of system being misused it is recommended that all personnel who use adjustable restraint systems receive competent training and certification.

Fixed Length Restraint Anchors

Just as for adjustable restraint systems, a fixed length restraint lanyard allows the operative to reach the edge of a fall hazard but no further and so prevents them from falling. The system is a fixed length and therefore the anchor only has to be able to withstand 3 times the body weight of the user, this is in case the operative trips – or for some reason runs at the open edge!! Where several users are connected to the same anchor point it’s recommended that at least three times the combined body weight of the users is used.

Working in fixed restraint prevents the operative falling and so removes some of the fall related issues, such as suspension trauma, fall height clearance etc.

If misused in such away as to allow a user to fall the consequences can result in serious injury or death.

Conclusion

The selection and positioning of anchors is a critical element of working at height. Life and death hangs on the choice, and it goes without question that they should be utterly reliable and have an adequate margin of strength to be able to withstand the dynamic and static forces that could be applied to them in service. Choosing the correct anchor should be done on a risk assessment matrix basis and be selected using the experience and knowledge of a competent person; if there is any doubt, a suitably qualified person should be used to certify the integrity of the anchor selection.

Leading Edge Safety provides courses which train delegates – enabling them to gain a recognised competency – to work at height, including the selection of suitable anchors.

Falls from height are one of the leading causes of death and serious injury in the work place, with a high personal cost to families and the subsequent financial cost to businesses.
Falls from height are one of the leading causes of death and serious injury in the work place, with a high personal cost to families and the subsequent financial cost to businesses.

With more than 50 years of experience in technical <a href=”http://www.leadingedgesafety.co.uk” >height safety</a> training and products, we have determined not only to provide the best fall protection and height safety training possible, but to also continuously develop new ideas, further our technological expertise, understand and implement new techniques and to repeatedly set higher standards of safe<a href=”http://www.leadingedgesafety.co.uk” > working at height.</a>

Number 1 Mistake

All too often Leading Edge trainers visit work sites only to find people working at height making the same mistake again and again.

Is it a minor mistake? No! It is one that would be catastrophic if the worker should fall.

Some people think that the number one mistake as a worker operating without safety equipment. Not so!

The number one mistake Leading Edge trainers see is where companies have incurred the cost of providing safety equipment, however through lack of the required knowledge the worker is using it incorrectly. The worker feels safe but doesn’t know that if he falls his protective equipment will fail.

It would be a tragedy, worse it would be unnecessary.

The number 1 mistake is connector misuse by the site worker.

What does misuse mean?

1. Choking – tying off incorrectly

2. Connecting to an unsuitable anchor point

3. Incorrect directional loading

1. Choking

This is where a site worker is supplied a lanyard, often with a small karabiner at the end. The site worker instinctively passes the lanyard around an anchor point e.g. a column or a beam, using the karabiner to choke i.e. tighten the lanyard around the anchor point.

The problem arises should the worker fall, further tightening the choked lanyard and subsequently applying a shock load inappropriately to the karabiner gate most likely causing the barrel of the karabiner to fail.

Karabiners are designed to accommodate tensile (pull) forces along their length and are at their weakest when the load forces are across the minor axis (width) or against the gate.

It is generally accepted that to engineer a connector to withstand the directional loading across the gate of the Karabiner which has been choked during a fall would require a gate strength of 5,000 lbs.

Note that this dynamic loading failure across the gate of the connector applies to all styles of connector i.e. scaffold hook, snap hook, and karabiner.

2. Connecting to an unsuitable anchor point
For example, a roof worker may instinctively connect to an handrail believing this to be a suitable fixing point.

Note! All temporary anchorage points must be able to withstand a 12 kN Load. If in doubt the anchor point should be approved by a structural engineer.

Leading Edge level 1 and 2 courses cover identifying suitable anchor points.

3. Scaffold Hooks

Scaffold hooks are often placed around scaffolding resting on a horizontal member, i.e. the gate of the scaffold hook will be forced open subject to the loading that would be imposed by the horizontal member in the event of a fall. This occurs because the downward direction or loading imposed by the cross-member is across the axis of the gate on the scaffold hook and will result in complete hook failure as the hook gate will subsequently bend open, or in worst-case scenario, will explode.

Summary of connector misuse

Often a lack of understanding of equipment performance and its limitations can result in site workers being issued with inappropriate safety equipment which is not suitable for its intended use.

For example the scaffold hooks are often used where a sling would be a much safer option.

To conclude this section on misuse of connectors, which can have devastating and even fatal consequences; it is important for a site management, Foreman and stores personnel to be competent to issue the appropriate equipment for the job.

Site workers, generally through lack of training are not aware of what they can do with the simplest of equipment such as connectors. It is therefore essential that both site workers and those managers responsible for height safety are adequately trained to be competent to carry out their duties safely.

Connector misuse is just one of 25 or more total equipment misuse areas leading edge commonly see on site.

Death to the number 1 mistake – not the site worker

How to choose and use connectors

Years of experience on site has convinced us at Leading Edge that the answer lies in the following:

1. Sufficient strength and load-bearing capabilities

2. Correct size

3. Easy to use

4. Lightweight to carry

5. Commercially acceptable

6. Being properly trained to use connectors and associated equipment

Inevitably this often leads back to specifying slings, be they webbing or cable.
These proprietary products have to be PPE items which are CE approved, designed to be an integral component in any fall arrest system and not just a bit of wire which somebody has terminated.

Slings fall into two categories

Wire -cable sling to EN795

Usually a 1m (but can reasonably be any length) galvanised steel cable, inside a hard but flexible resin jacket, making it more durable from abrasion and corrosion, also protecting the anchorage point from cable abrasion. This type of configuration is commonly used in conjunction with inertia reels.

Webbing slings to EN795

This is a product which is lightweight and easy to carry around, which adds to its attraction and is relatively inexpensive. It is often used when anchoring to a scaffold pole.

Correct use of scaffold hooks and karabiners

Scaffold Hook

It may be the case that it is easier to tie off with a scaffold hook than a sling and standard karabiner, but a scaffold hook is designed to be suspended off horizontal Anchorage e.g. of a horizontal scaffold tube, ensuring correct directional loading (vertical downward load).
Karabiners

As mentioned earlier karabiners are weakest when they are loaded across or against their gate.

This means that it is vitally important that the karabiner is always loaded along its length and never across its width, which would pull against its gate or caused the karabiner to take a force against the gate. So please take care

fall arrest

fall arrest products

The Number 1 Mistake Using Fall Arrest Equipment

Author: Drew Beardmore
Leading Edge Safety height safety training courses and equipment are specifically designed for anyone whose job requires them to work at height and involves using the necessary safety equipment required to do this.

For more information visit www.leadingedgesafety.co.uk