By Tim Nye, Installed Systems Manager, Safesite Ltd
Recently we've been sharing some images of systems and equipment we've come across on site that are not fit or safe to use, either because the components have been damaged or the system has been installed incorrectly. This eyebolt is another classic example of an incorrect installation.
“We were told it had passed a 6kN pull test so it must be fine.” WRONG!
Understanding BS 7883
This eyebolt is installed on top of a parapet and is a perfect illustration of a frequent misunderstanding we come across of how eyebolts function and what forces the base structure must be capable of withstanding.
The code BS 7883: 2005 Section 8 is perfectly clear and states that eyebolts fitted into traditional bonded brickwork should only be into LOAD-BEARING solid masonry.
8.1.3 Wherever anchor devices are to be used it is essential to ensure that the structure has sufficient strength and stability to support the loads that could be applied to the anchor device in the event of a fall being arrested. This is especially important in the case of brickwork or combined brickwork/blockwork.
8.1.4 Anchor devices should only be fixed in, or attached to, load-bearing structural members if the strength of these structural members has been assessed and they have been found to be strong enough to support the load that could be applied to the anchor device in the case of a fall being arrested. Anchor devices should not be fixed in non-load-bearing infill panels without specialist advice being first obtained.
Anyone with general construction experience of what load-bearing means should be able to understand this, but unfortunately there are numerous installations where it appears that this knowledge is either missing or, more worryingly, being ignored. A clear understanding of correct installation, and implementing it, is essential as the consequences of incorrect installation can quite literally be fatal.
The following diagram from BS7883 shows an example of an anchor device suitable for load bearing solid masonry, used in conjunction with resin bonded structural anchor.
BS 7883 Annex B gives additional advice on fitting locations around a window and from this you can see that the minimum dimension for fixing below a window cill 'd' is 600mm. This is because this is 'non-loadbearing' and it is only once you have a build-up of 600mm that it can be considered as satisfactory. However, on a parapet even 600mm may be inadequate as traditional brick parapets are often in poor condition and are less stable than a window where the frame, surrounding walls and non-weathered situation all add to the strength of this position.
The diagram below of a fixed pane plus external opening window, side hung shows the minimum dimension for fixing below a window cill.
As with any type of work, particularly installation of fall protection systems, competency is essential. According to BS7883:
8.1.5 The position for the installation of anchor devices should be determined by a competent person, taking the manufacturer's instructions into account, and, where necessary, in consultation with a suitably qualified engineer.”
Unfortunately this photograph clearly shows that the eyebolt has been installed by someone who was not competent to do so.