1、BS 8411:2007Code of practice for safety nets on construction sites and other worksICS 91.200; 91.220NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDPublishing and copyright informationThe BSI copyright notice displayed in this document indicates when the documen
2、t was last issued. BSI 2007ISBN 978 0 580 50803 5The following BSI references relate to the work on this standard:Committee reference B/514/27Draft for comment DC01/105834Publication historyFirst published May 2007Amendments issued since publicationAmd. no. Date Text affectedBS 8411:2007 BSI 2007 iB
3、S 8411:2007ContentsForeword iiIntroduction 11 Scope 12 Normative references 13 Terms and definitions 24 Layout and applications 45 Planning of net installations 116 Erection, use and dismantling 147 Care and maintenance of safety nets 20AnnexesAnnex A (informative) Legal considerations 25Annex B (in
4、formative) Assessing the reliability of safety nets 26Annex C (informative) Competence, supervision and training 29Bibliography 31List of figuresFigure 1 Eaves bagging to avoid waisting 8Figure 2 Typical attachment device 10Figure 3 Maximum deflection for nets greater than 35 m2in area 18Figure 4 Ty
5、pical UV test tag 21Figure 5 Typical repair tag 21List of tablesTable 1 Classification of nets according to mesh size and energy absorption 5Summary of pagesThis document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 31 and a back cover.BS 8411:2007ii BSI 2007ForewordPub
6、lishing informationThis British Standard was published by BSI and came into effect on 31 May 2007. It was prepared by Subcommittee B/514/27, Nets and sheets, under the authority of Technical Committee B/514, Access and support equipment. A list of organizations represented on this committee can be o
7、btained on request to its secretary.Relationship with other publicationsThis British Standard shows how safety nets manufactured to conform to BS EN 1263-1 and arranged in the manner specified in BS EN 1263-2 can be used to enhance safety for those working at height.Use of this documentThis British
8、Standard is intended for use by designers, engineers, scaffolding contractors, safety net erectors and authorities having jurisdiction.As a code of practice, this British Standard takes the form of guidance and recommendations. It should not be quoted as if it were a specification and particular car
9、e should be taken to ensure that claims of compliance are not misleading.Any user claiming compliance with this British Standard is expected to be able to justify any course of action that deviates from its recommendations.Presentational conventionsThe provisions in this standard are presented in ro
10、man (i.e. upright) type. Its recommendations are expressed in sentences in which the principal auxiliary verb is “should”.Commentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element.Contractual and legal considerationsThis
11、 publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Attention is particularly drawn to the legal requirements listed in Annex A. BSI 200
12、7 1BS 8411:2007IntroductionSafety nets are used on construction sites and similar works mainly to arrest a persons fall, although they can also be used to catch or contain debris. They reduce injury because they absorb a large proportion of the energy from a falling body through suffering plastic de
13、formation when impacted, dissipating this energy with minimum rebound.They provide a collective protection system that is constantly available for those persons working above it, i.e. one which requires no input and little co-operation from the workers it is being used to protect.Safety nets are man
14、ufactured from synthetic materials. While they are lightweight and rot-resistant, they can be easily damaged by improper use, wear and tear, heat or flame, handling and storage. They can also be adversely affected by weathering, UV degradation and environmental factors, resulting in some strength lo
15、ss. It is therefore essential that safety nets are subject to regular examinations by competent persons including periodic testing in accordance with the manufacturers instructions.1 ScopeThis British Standard provides guidance and recommendations on the safe use, erection and effective maintenance
16、of safety nets on construction sites and other works where there is a risk of fall. It is applicable generally to safety nets that conform to BS EN 1263-1 and that are erected within the positioning limits given in BS EN 1263-2. However, as these standards are very specific, this British Standard al
17、so gives advice on how to assess the reliability of safety nets outside these limits.NOTE This advice is given in Annex B.This British Standard covers safety net systems “S”, “T” and “U” as given in BS EN 1263-2. It does not cover system “V”.This British Standard does not cover temporary support net
18、s, which are intended for persons to stand on either for access, egress or work.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the ref
19、erenced document (including any amendments) applies.BS 7883, Code of practice for the design, selection installation, use and maintenance of anchor devices conforming to BS EN 795BS 7955:1999, Containment nets and sheets on construction works Specification for performance and test methodsBS EN 362,
20、Personal protective equipment against falls from a height ConnectorsBS EN 795, Protection against falls from a height Anchordevices Requirements and testingBS 8411:20072 BSI 2007BS EN 1263-1:2002, Safety nets Part 1: Safety requirements, test methodsBS EN 1263-2:2002, Safety nets Part 2: Safety requ
21、irements for the positioning limits3 Terms and definitionsFor the purposes of this British Standard the following terms and definitions apply.3.1 anchorage devicedevice or system used to connect a safety net to an anchor point3.2 anchor pointfeature or position on a structure to which a safety net i
22、s attached3.3 bagginggathering up surplus net at the edges or providing reinforcing at unsupported eaves or at frames3.4 border ropeNOTE See also BS EN 1263-1. rope that passes through each mesh at the perimeter of a safety net and determines the overall dimensions of the net3.5 catching widthdistan
23、ce beyond the working area into which a person could fallNOTE The extent of the catching width will depend on the horizontal trajectory of the falling body together with the height of the fall plus an additional area of at least 2 m width.3.6 classclassification of a net according to energy absorpti
24、on capacity and mesh size3.7 competent personperson with sufficient professional or technical training and knowledge, actual experience and authority to enable them to: carry out their assigned duties at the level of responsibility allocated to them; recognize potential hazards related to the work (
25、or equipment) under consideration and be able to implement adequate control measures; detect any defects or omissions in that work (or equipment), recognize any implications for health and safety caused by those defects and omissions, and be able to specify a remedial action to mitigate those implic
26、ationsNOTE 1 “Authority” in this context means authority delegated to the individual by his or her employer.NOTE 2 See Annex C for guidance on competence, supervision and training.NOTE 3 See also BS EN 1263-1. BSI 2007 3BS 8411:20073.8 containment netcontainment sheetNOTE Containment nets and sheets
27、 are also known as debris nets.relatively fine net or sheet conforming to BS 7955, laid over a safety net and used to catch or contain lightweight debris3.9 coupling ropeNOTE This is sometimes referred to as a lacing rope.rope that joins two or more safety nets together3.10 eaves baggingrigging tech
28、nique that removes the natural waisting form, or horizontal deflection, at an unsupported net perimeter3.11 initial sagamount of sag induced by the weight of a net when influenced by the horizontal tension within the net3.12 karabinersafety link formed as a complete loop with a spring-loaded entry g
29、ate safeguarded in the closed position, conforming to BS EN 3623.13 laced jointjoint formed around items, such as service pipes and ducts, which penetrate the net system3.14 mesh cordNOTE This is often referred to as mesh rope.cord from which the mesh of a net is constructed3.15 mesh sizedistance be
30、tween the centres of mesh cordssimplified from BS EN 1263-13.16 net systemarrangement of mesh, border ropes, coupling ropes, tie ropes and/or anchorage devices, and supporting framework, which are linked together as a system to provide a means of arresting falls3.17 safety netnet itself plus border
31、rope, test meshes or cords, labels and serial numbers3.18 safety zonearea immediately below the maximum expected (or calculated) deflected shape formed by a safety net as it is struck by a falling body, which is kept clear of obstructions3.19 supporting frameworkstructure to which nets are attached
32、and which can contribute to the absorption of the kinetic energy due to a fall3.20 test cordNOTE Test cords are only present in knotted nets.separate sacrificial length of net cord of the same material as the net, produced in the same batch and used for periodic testing3.21 test meshNOTE Test meshes
33、 are present in knotless nets and occasionally in knotted nets.separate sacrificial area of net mesh of the same material as the net, produced in the same batch and used for periodic testingBS 8411:20074 BSI 20073.22 tie roperope used for securing the border rope of a safety net to a suitable anchor
34、age3.23 under-rollingmeans of reducing the width of a standard net to fit a specific space or to provide a strong edge to which the tie rope or attachment system is attached 3.24 waistingeffect of the self-weight of a net at an unsupported perimeter where the net pulls horizontally away from an adja
35、cent structure or the required line of the net4 Layout and applications4.1 Layout4.1.1 GeneralSafety nets may be used by themselves or in combination with other fall arrest and fall prevention systems in maintenance, construction works, theatres, prisons, manufacturing, etc., to provide protection a
36、gainst the consequences of a fall at openings or edges, or where working over or near fragile materials. Safety nets of various sizes may be linked together (see 6.3.4) so as to span large areas.Nets may be used in the form of a protection fan (e.g. BS EN 1263-1:2002, Figure 2), enhanced where requi
37、red, by placing containment nets or sheets conforming to BS 7955 over the safety nets to prevent smaller debris from falling through the net. The size and spacing of the containment net should be suitable and sufficient for the type of material likely to fall into it. Consideration should be given t
38、o the avoidance of gaps in the containment net at edges and around service ducts, etc.In order to minimize the risk of injury to those who might fall into safety nets, nets should be capable of deforming and deflecting sufficiently under impact to largely absorb the energy of the falling person, thi
39、s deformation and deflection being possible through the net cords slipping and tightening (knotted nets) or net meshes (knotless nets) deforming or stretching through plastic deformation. Tie ropes and border ropes might also stretch under load, so absorbing some of the falling energy. Safety nets s
40、hould have sufficient clearance below them in order to allow for this deflection while ensuring that the person falling does not strike any object.Generally, the greater the fall height and the smaller the net area, then the greater the energy absorption capacity per unit area that is required to sa
41、fely contain the fall (for further information see Annex B). BSI 2007 5BS 8411:2007While safety nets are designed to catch people, they can also be used to retain or control debris although debris within the net can also injure anyone subsequently falling into it. The effect of debris in the net wil
42、l depend on the mass, shape, nature and falling height of the debris. If therefore it is assessed that debris might fall into the net and cannot be regularly cleared, advice should be obtained from a competent person as to any limitations that should be observed. In particular this assessment should
43、 consider the likelihood of the net being overloaded causing excessive deflection and tension in the net, ties and anchorages, and/or the risk of material bouncing out of or being deflected from the net, to the danger of anyone in the vicinity. Safety nets used with or without containment nets as pr
44、otection fans (system “T) should not be used to catch materials deliberately thrown into them or for the storing of debris or materials.Following the impact of any heavy objects into the nets, the nets should be taken out of service for checking or testing, and repaired when necessary (see 7.1.1 and
45、 Clause 7 generally).Under normal circumstances, damaged nets should be immediately taken out of service. However, as an immediate short-term measure, damage to a single mesh cord could be repaired by a suitably competent person, with a tie rope. There should not be more than two temporary repairs i
46、n a single net. Once the immediate work is complete the damaged net should be either repaired fully before reuse, or destroyed (see Clause 7).Care should be taken to ensure that no one enters the areas below the safety nets when persons are working above them unless there is no risk of them being st
47、ruck by falling objects.4.1.2 Classification of safety netsSafety nets conforming to BS EN 1263-1 are classified according to mesh size and energy absorption characteristics, as shown in Table 1. Two energy absorption capabilities are referenced, each in two mesh sizes.NOTE Safety nets of both mesh
48、sizes described in BS 1263-1 are suitable for use, although the 100 mm mesh net usually is lighter and will have a lower initial sag due to its self-weight. All classes of safety net are available as either diamond mesh (when their designation includes the letter “D”) or square mesh (when their desi
49、gnation includes the letter “Q”) (see BS EN 1263-1:2002, Figure 1). Generally a square mesh will sag less when rigged. Therefore at its mid-point it will be closer to the working level, thus minimizing the possible fall height (see 4.1.3).Table 1 Classification of nets according to mesh size and energy absorptionType (from BS EN 1263-1) Energy absorptionkJ Max. mesh sizemm A1 2.3 60 A2 2.3 100 B1 4.4 60 B2 4.4 100 BS 8411:20076 BSI 20074.1.3 Positioning parameters and net selectionSafety nets should be
