Furse have now launched an updated Guide to BS EN Protection Against Lightning. This latest edition incorporates guidance on the. This handbook offers a guide for any designers of the structural Lightning protection system to comply with the requirements of BS EN range of standards. An overview of BS EN , its impact on lightning protection and the support and advice Earthing design considerations and full details of the Furse range of earthing materials .. illustrations and design examples, the Guide provides.
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Square tape clamp Part no CT Figure 4. On many occasions this is not practical to carry out. Lateral connections either by fortuitous metalwork or external conductors made to the down conductors at regular intervals see Table 4.
Furse release 3rd edition of their renowned Guide to
We have, where it has been possible, corrected the errors in this guide. Air rods or free standing masts The effectiveness of an isolated free standing mast used to protect a small object can be proven by the protection angle method.
For structures made vs non-conducting materials the above practices are essential in order to minimise damage to equipment or data corruption. The generic equation for evaluating each risk component is: Application of the rolling sphere to catenary conductors forming an isolated system Figure 4. The dimension for tape and stranded conductors fixed to horizontal surfaces should be 1,mm and not the stated mm.
Shielding in subsequent inner Ne can be accomplished by either durse further spatial shielding measures, for example a screened room, or through the use of metal cabinets or enclosure of the equipment. The line must bisect the sphere circle such that the areas shaded of over and under estimation of protection when compared to the rolling sphere method are equal.
The down guidee spacing corresponds with the relevant Class of LPS.
With reference to Figure 4. Our interpretation of this clause when applied to Type A bd is that with the test link removed and without any bonding to other services etc, the earth resistance of each individual huide electrode should be measured. A coordinated set of SPDs should effectively operate together as a cascaded system to protect equipment in their environment.
BS EN part 1 is an introduction to the other parts of the standard and essentially describes how to design a Lighting Protection System LPS in accordance with the accompanying parts of the standard. Protection of electronic systems from transient overvoltages can prevent: This is to ensure that those rn bars likely to carry lightning currents have secure connections from one length to the next.
Shields are primarily fitted to prevent residual interference, for example on signal lines.
Lightning Protection Standard BS EN 62305
KS4 relates to the rated impulse withstand voltage of the system. Risk Management BS EN part 2 risk management approach, does not concentrate so much on the purely physical damage to a structure caused by a lightning discharge, but more on the risk of loss of human life, loss of service to the public, loss of cultural ej and economic loss.
Although BS advocates the use of reinforcing for equipotential bonding, BS EN emphasises on its importance. Coordinated SPDs simply means a series of SPDs installed in a structure from the equipotential bonding or lightning current SPD at the service entrance through to the overvoltage SPD for the protection of the terminal equipment should compliment each other such that all LEMP effects are completely nullified.
This publication offers an informative guide for designers, engineers, architects, consultants and contractors and has been produced with the following aims.
Furse release 3rd edition of their renowned Guide to Lightning Protection
yo The centres between these down conductors should not be less than one third of the distances given in Table 4. The standard advocates a low earthing resistance requirement and points out that can be achieved with an overall earth termination system of 10 ohms or less.
The relationships of all of the above parameters are summarised in Table 2. The function of the external system is to intercept the strike, conduct and disperse it safely to earth.
A Guide to BS EN Protection Against Lightning_图文_百度文库
However the live conductors within these service cables need to be equipotentially gguide at the service entrance through the use of SPDs. Such underground electrical services are not subject to direct lightning currents and therefore do not transmit partial lightning currents into the structure. They are not employed to protect electrical and electronic systems, which require the use of coordinated SPDs in accordance with the standard.
In addition the standard contains the following explicit statement that we believe applies to the UK: Possible protection measures against equipment failure include: The distribution of these particles normally gives rise to a negative charge ti up at the base of the cloud Figure 1.
The withdrawal of part 5 impacts on some sections, paragraphs and clauses within the other four fn, but these references had already been published prior to the decision to abandon the furtherance of part 5.
The relationship between differing types of SPDs, their testing regimes and typical application is illustrated in Table 5. One of the first changes to realise is that this new approach to risk management looks at risk in a far broader sense than merely the physical damage that furxe be caused to a structure sn a lightning discharge.
Type of air termination system Number of down conductors kc Earthing arrangement Type A Earthing arrangement Type B km l n Single rod Wire Mesh Mesh 1 2 4 and more 4 and more, connected by horizontal ring conductors 1 0. Typical methods of bonding to steel reinforcement within concrete BS EN Natural components www.
Although lightning current discharges are a high frequency event, at present most measurements taken of the earthing system are carried out using low frequency proprietary instruments. As the main distribution board falls within overvoltage impulse category III see Table 5.
The dotted line represents the path of the centre of the sphere as it is rolled over the building. Annex C of BS EN describes the principles and detailed frse of SPD coordination, which depends on factors such as SPD technologies, although in practice guied of SPDs should supply installation guidance to ensure coordination is achieved.
Again, four different air termination mesh sizes are defined and correspond to the relevant Class of LPS see Table 4.
If an air rod or a conductor on the edge of the roof was installed then a zone of protection angle could not be claimed because the rolling sphere had already identified that the upper 20m was not protected. This doubling may occur if the equipment corresponds.
Annex NC helps to assess the amount of loss to a structure LX.