The purpose of a lightning protection system is to protect buildings from direct lightning strikes and possible fire, or from the consequences of the load-independent active lightning current (non-igniting flash of lightning).
If national regulations, e.g. building regulations, special regulations or special directives require lightning protection measures, they must be installed.
Unless these regulations contain specifications for lightning protection measures, a lightning protection system (LPS) Class III meeting the requirements of IEC 62305-3 (EN 62305-3) is recommended as minimum. Otherwise, the need for protection and the choice of appropriate protection measures, should be determined by risk management.
Of course other additional corresponding national standards and legal requirements may be applicable and have to be taken into account. In the following some examples of German directives, standards and legal regulations. In Germany further information on how to determine the type of lightning protection systems for general buildings and structures can be found in the following directive of the VdS:
VdS-Richtlinie 2010 “Risikoorientierter Blitz-und Überspannungsschutz, Richtlinien zur Schadenverhütung”. [engl.: “Risk orientated lightning and surge protection, guideline for prevention of damage”]
For example, the building regulations of the State of Hamburg (HbauO § 17, Abs. 3) require a lightning protection system to be installed if lightning can easily strike a building because of:
- Its length,
- Its height, or the use to which it is put, or if
- It is expected that a lightning strike would have serious consequences.
A lightning strike can have particularly serious consequences for buildings and structures owing to their location, type of construction or the use to which they are put.
A nursery school, for example, is a building where a lightning strike can have serious consequences because of the use to which the building is put. The interpretation to be put on this statement is made clear in the following court judgement:
Extract from the Bavarian Administrative Court, decision of 4 July 1984 – No. 2 B 84 A.624.
- A nursery school is subject to the requirement to install effective lightning protection systems.
- The legal requirements of the building regula-tions for a minimum of fire-retardant doors when designing staircases and exits also apply to a residential building which houses a nursery school.
For the following reasons:
According to the Bavarian building regulations, buildings and structures whose location, type of construction or the use to which they are put, make them susceptible to lightning strikes, or where such a strike can have serious consequences, must be equipped with permanently effective lightning protection systems.
This stipulates the requirement for effective protective devices in two cases. In the first case, the buildings and structures are particularly susceptible to lightning strikes (e.g. because of their height or location); in the other case, any lightning strike (e.g. because of the type of construction or the use to which it is put) can have particularly serious consequences.
The plaintiff´s building falls within the latter category because of its present use as a nursery school.
A nursery school belongs to the group of buildings where a lightning strike can have serious consequences because of the use to which the building is put. It is of no consequence that, in the annotations to the Bavarian building regulations, nursery school are not expressly mentioned in the illustrative list of buildings and structures which are particularly at risk, alongside meeting places.
[pullquote_left]The risk of serious consequences if lightning strikes a nursery school arises because, during the day, a large number of children under school age are present at the same time.[/pullquote_left]The fact that the rooms where the children spend their time are on the ground floor, and that the children could escape to the outside through several windows – as put forward by the plaintiff – is not a deciding factor.
In the event of fire, there is no guarantee that children of this age will react sensibly and leave the building via the windows if necessary.
In addition, the installation of sufficient lightning protection equipment is not too much to expect of the operator of a nursery school. A further section of the Bavarian building regulations requires that, amongst other things, staircases must have entrances to the cellar which have self-closing doors which are, at least, fire-retardant.
The requirements do not apply to residential buildings with up to two flats. The respondent only made the demand when the plaintiff converted the building, which was previously residential, into a nursery school as well, in accordance with the authorised change of use.
The exemption provision cannot be applied to buildings which were built as residential buildings with up to two flats, but which now (also) serve an additional purpose which justifies the application of the safety requirements.
For these reasons, it is necessary that all buildings and structures which are at risk of such events are equipped with permanently effective lightning protection systems.
Lightning protection systems always required
Buildings and structures where a lightning protection system must always be included because, in these cases, the German law has affirmed the need, are:
1 Assembly places with stages or covered stage areas and assembly places for the showing of films, if the accompanying assembly rooms in each case, either individually or together, can accommodate more than 100 visitors;
2 Assembly places with assembly rooms which individually or together can accommodate more than 200 visitors; in the case of schools, museums and similar buildings, this regulation only applies to the inspection of technical installations in assembly rooms which individually can accommodate more than 200 visitors, and their escape routes;
3 Sales areas whose sales rooms have more than 2000 m2 of floor space;
4 Shopping centres with several sales areas which are connected to each other either directly or via escape routes, and whose sales rooms individually have less than 2000 m2 of floor space but having a total floor space of more than 2000 m2;
5 Exhibition spaces whose exhibition rooms individually or together have more than 2000m2 of floor space;
6 Restaurants with seating for more than 400 customers, or hotels with more than 60 beds for guests;
7 High-rise buildings as defined in the Hamburg building regulations (HbauO);
8 Hospitals and other buildings and structures having a similar purpose;
9 Medium-sized and large-scale garages as defined in the Hamburg regulations for garages (Hamburgisches Gesetz- und Verord-nungsblatt);
10. Buildings and structures
10.1 with explosive materials, such as ammunition factories, depots for ammunition and explo-sives,
10.2 with factory premises which are at risk of explosion, such as varnish and paint factories, chemical factories, larger depots of combustible liquids and larger gas holders,
10.3 particularly at risk of fire, such as:
- Larger woodworking factories,
- Buildings with thatched roofs, and
- Warehouses and production plants with a high fire load,
10.4 for larger numbers of people such as:
- Homes for the elderly and children’s homes,
- Correctional facilities
- and railway stations,
10.5 with cultural assets, such as:
- Buildings of historic interest,
- Museums and archives,
10.6 towering above their surroundings, such as:
- High chimneys,
- High buildings.
The following list provides an overview of the relevant “General Provisions” in Germany which deal with the issue of requirement, design and inspection of lightning protection systems.
Resource: Ligthning Protection Guide (www.dehn.de)