05 APPLICATION PROPOSAL External and Internal Lightning Protection for Churches SV05/E/0112 External and Internal Lightning Protection for Churches Introduction Steeples, due to their significant height, are at special risk of lightning strikes. Considering the cultural and historical value of churches and in view of the fact that churches are places where a lot of people are gathering frequently, the necessity of lightning protection measures is quite obvious. External lightning protection system A lightning protection system Class III meets the standard requirements for steeples and churches. In some special cases, for example buildings of cultural heritage or significant importance, additional measures in accordance with IEC 62305-2 (EN 62305-2) have to be carried out. Nave The nave’s own lightning protection system has to be connected on the shortest possible route with the down-conductor system of the steeple (Figure 1). In case of a transept, the air-termination conductor along the ridge must have a down conductor at both ends. tors must be connected with the nave’s external lightning protection system on the shortest route. Down conductors basically have to be installed outside at the steeple, an installation inside of it is not allowed. Additionally the separation distance “s” to metal components and electrical installations in the steeple (e.g. clock mechanisms, belfry, etc.) and under the roof (e.g. air conditioning, ventilation and heating systems) must be maintained by a corresponding arrangement of the external lightning protection system. This required separation distance to be kept may become a problem especially at the church clock. In this case, the risk of dangerous sparking can be avoided by using for example DEHNiso spacers to have the necessary distance between the down conductor and the clock. In new, reinforced concrete design churches, the reinforcement steel may be used as down-conductor system if the steels are safely and conductively interconnected. The reinforcement of pre-cast concrete parts may be used as down-conductor Steeples Steeples up to a height of 20 m must be equipped with a down conductor. If steeple and nave are built together, this down conductor has to be connected on the shortest possible route with the external lightning protection system of the nave (Figure 2). In case the steeple down conductor coincides with a nave’s down conductor, a common down conductor may be used here. At least two down conductors are necessary in case of steeples higher than 20 m and one of these down conduc- Figure 1 External lightning protection system at the nave Figure 2 Down-conductor system installed at the steeple APPLICATION PROPOSAL 05 External and Internal Lightning Protection for Churches Page 2 www.dehn.de 05 APPLICATION PROPOSAL system, if there are connection points for the continuous interconnection of the reinforcement. Equipotential bonding Purpose and intention of equipotential bonding is to avoid potential differences between different extraneous conductive parts. Equipotential bonding has to be implemented carefully according to IEC 60364-4-41, 60364-5-54 and 60364-6. For lightning equipotential bonding, the minimum cross section of the earth conductor between surge protective devices and equipotential bonding has to be at least 16 mm2 Cu. DV ZP TNC 255 (TN-C system) DV ZP TT 255 (TT system) Part No. 900 390 Part No. 900 391 DG M TT 275 (TT system) Part No. 952 310 DG M TT 2P 275 (TT system) Part No. 952 110 see figure 4 DFL M 255 Part No. 924 396 BXTU ML4 BD 0-180 (4 wires)* Part No. 920 349 + BXT BAS Part No. 920 300 CTR DGA G BNC + fixing bracket Part No. 929 042 Part No. 106 329 * use only if compatible with system parameters CTR hymn display mot 3~ Lightning and surge protection for the power supply system As churches shall be equipped emergency call with an external lightning protection system, lightning equipotential bonding also has to be carried out inside the bell building by directly connecting M M control the metal frame of the buildELS SEB ing, the metal installations and the external conductive parts with the lightning protection system. Additionally, all incoming conductive power supply Figure 3 Principle of an external and internal lightning protection at a church nave and steeple and information technology systems have to be integrated the terminal device is ≤ 5 m additional protective into the lightning protection equipotential bonddevices are not necessary. ing via lightning current arresters (e.g. walkway/ path lighting). Another important measure is the surge protection of the electrical installation inside of the nave Lightning equipotential bonding shall be impleand the steeple. For this purpose all wires of the mented immediately at the entrance point of the electric conductors leading into the steeple will cables into the building. The main distribution be protected by surge protective devices up in the board of the power installation of a church is often steeple as well as in the corresponding distribuin the sacristy. Lightning equipotential bonding of tion board down in the steeple or in the sacritsty the low-voltage consumer installation is carried (Figure 3). Depending on the used control techout according to Figure 3 with the combined lightnique, either surge protective devices type DEHNning current and surge arrester DEHNventil (DV). guard or BLITZDUCTOR XT may be installed here. If the conductor length between DEHNventil and APPLICATION PROPOSAL 05 External and Internal Lightning Protection for Churches www.dehn.de Page 3 External and Internal Lightning Protection for Churches motor-driven façade motion train 1 1 3 5 7 N PE control line NYY-J 10 x 2.5 mm2 TN-S / TT system ... DG S 275 Part No. 952 070 DGP C S Part No. 952 030 M ~ 1 2 1 2 Figure 4 Installation of surge protective devices in the bell control system/bell automation Acoustic systems and other electrical equipment such as organ, floor heating, light control systems, hymn display, must be considered separately. 6 x DEHNguard DG S 275 Part No. 952 070 DG MOD 275 DEHNguard DG MOD 275 DEHNguard DG MOD 275 DEHNguard DG MOD 275 DEHNguard DG MOD 275 2 1 2 N DEHNguard DG MOD 275 2 1 2 N DEHNguard In the area near the distribution board for the bell control system all incoming conductors will be protected by surge protective devices. It has to be minded that the earth terminal of the surge protective devices will be connected with the local protective conductor (PE) of the distribution board and not directly with the equipotential bonding bar down in the steeple. One possible solution is shown in Figures 4 and 5. The conductors for the motor-driven façade motion train will be equally protected. Here likewise all incoming conductors will be equipped with DEHNguard surge protective devices (see Figure 6). PE DG MOD 275 DEHNguard Figure 6 Example of how to use the surge protective devices for the clock motor (up in the steeple) in a TNS system DEHNguard DG S 275 Part No. 952 070 Figure 5 Installation of surge protective devices in the bell control system / bell automation APPLICATION PROPOSAL 05 External and Internal Lightning Protection for Churches Page 4 www.dehn.de 05 APPLICATION PROPOSAL APPLICATION PROPOSAL 05 External and Internal Lightning Protection for Churches www.dehn.de Page 5 DEHN + SÖHNE GmbH + Co.KG. Hans-Dehn-Str. 1 Postfach 1640 92306 Neumarkt Germany Tel: +49 9181 906-0 FAX: +49 9181 906-1333 www.dehn.de info@dehn.de Type designations of products mentioned in the application proposal being at the same time registered trademarks are not especially marked. So if there is no marking of or ® this does not mean that the type designation is a free trade name. Neither it can be seen whether patents or utility models and other intellectual and industrial property rights are available. We reserve the right to introduce changes in performance, configuration and technology, dimensions, weights and materials in the course of technical progress. The figures are shown without obligation. Misprints, errors and omissions as well as alterations expected. Reproduction in any form whatsoever is forbidden without our authorisation. Brochure No. SV05/E/0112 © DEHN + SÖHNE 2012