Protection aim 1: Basic principles
Limit the spread of fire
To prevent the fire from spreading to other parts of the building, the installations required for ceiling and wall penetrations must be reliably sealed. This is done using insulation systems, which effective prevent the spread of fire and smoke.
Requirements for cable penetrations - Insulation
Electrical cables and pipes may only be run through walls and ceilings at the ends of rooms, although there must be no opportunity for fire and smoke to spread. This requirement is fulfilled by insulation systems. These permit the reliable sealing of the ceiling and wall penetrations required for installations against fire and smoke. The following requirements apply to cable penetrations:
- The spread of fire and smoke must be prevented.
- Room closure must be guaranteed.
- On the side of the insulation away from the fire, the surfaces of cables, pipes, cable support systems and the surface of the insulation may not heat up strongly to an impermissible level.
Spacing regulations
If only individual cables or small cable bundles are run through fire-resistant components, they can be routed through individual holes with an appropriate spacing. The individual holes must be closed off with mineral substances or substances which foam up in a fire. In so doing, the greatest diameter defines the distance to the smaller cables. The risk of fire spread does not increase in this manner. Individual cables without a diameter limit are permitted without insulation - a ring gap closure around the cable is sufficient.
Proofs of application
The effect or application of insulation systems required by law must be proven through tests. These fire tests are carried out by official materials' testing institutes or accredited testing institutes all over the world on the basis of testing standards. The fire tests are the basis of the approval as the construction product with the proper use of being used as an insulation system.
Contents of the approvals
The certificates of approval specify the following criteria, among other things, for the application area and installation:
- Fire resistance classes
- Installation conditions e.g. installation in concrete walls
- Maximum insulation dimensions
- Minimum cable insulation thickness
- Minimum ceiling/wall thickness
- Materials to be used to create the insulation
- Approved installations e.g. cables or cable support systems, pipes
- Sequence and type of installation
- Execution of a retroinstallation
- Data on the duty of the manufacturer to train people who create the insulation
Tests
The testing of the insulation takes place in a special tests, in which the sample installations on test are heated up according to a standard temperature-time curve. This curve is internationally standardised according to ISO 834-1 and used around the world for fire tests. It forms the so-called "flash-over", which is the most critical phase of a fire. After the smoldering fire phase, all the combustible gases located in the fire chamber ignite suddenly, meaning that the temperature rises very quickly. This installed installation must withstand this full fire.
Classifications and certificates
After successfully passed tests, the results are documented by the testing institutes and the systems classified, e.g. according to the results of EN 13501. In most European countries, this classification report can be used as a proof of suitability in conjunction with the manufacturer's mounting instructions. However, some countries require a general construction approval. This can be applied for with the testing documentation and classification report at an approval office accredited by the European Organisation for Technical Approvals (EOTA). Classifications according to UL (Underwriters Laboratories) deviate from this.
Labelling obligation
Each piece of insulation must be permanently labelled with a sign. The labelling is necessary, on the one hand, to prove that an approved valid insulation system was used. On the other hand, it is used to identify the system for any later installations. The systems were constructed and tested using different materials and can prove the function of these special material combinations. If combined with other components which do not belong to the system, then this can have a negative impact on behaviour if there is a fire. This must be avoided. This creates the requirement of the approval offices for user training courses, who should know the basic principles of construction law and how to handle insulation materials.
Construction types of cable and combination insulation
Various components require appropriately suitable insulation measures. Thus, the selection of the matching insulation system is dependent on various parameters. The application options range from solid walls and ceilings made of masonry and concrete through to dry-construction partitions. The installations which can pass through can be made up of cables and cable support systems, combustible and non-combustible pipes or a combination of both. There are requirements, for example, for a dust- and fibre-free installation, destruction-free retroinstallation and certain pressure resistances. Various cable, pipe and combination insulation is available to close openings in ceilings and walls with fire protection classification. These fulfil the necessary standards and possess the appropriate approvals.
Typical insulation systems
Special mortar, mineral fibre plates with coating, fire protection foam, 1-component compounds, foams and fittings, boxes, silicones and special rubberised modules. All the systems possess special fire protection components and additives, which fulfil a safe function in case of fire in accordance with the testing standard.
Assignment rule
Classic insulation is created according to the so-called 60% assignment rule. This means, from the component opening through which the installations run, a maximum of 60% of the area may be assigned with cables, support systems, pipes, etc. The remaining area, the remaining 40%, must be filled with fire protection material which is "active" in case of fire or be closed off. In this case, "active" does not mean that the material must react chemically. It must only ensure that the heat transmission via the media and the transmission of fire and smoke are prevented. This can take place through chemical reactions, but also through good acceptance of the heat energy and the resulting cooling effect. Some systems can be "fully" assigned. However, they must be tested and approved for this application.
Installations
All the insulation systems are tested with various specified installations, in order to cover different application areas. Thus, there are pure cable insulations which can be mounted by any electrical installation engineer, but there are also so-called combination insulations. Plastic and metal sanitary pipes can be run through these together with electrical cables.
In addition, some insulation has been tested for special cables, e.g. hollow shaft cables or cables of split air-conditioning units. The approved installations differ from system to system.
Support measures
If there is a fire, large forces impact on the installations. For this reason, fastenings of support systems may fail and the insulation may be subjected to mechanical loads. To prevent this, additional supports for the passed-through installations must be mounted at a defined spacing in front of the surfaces of the insulation. The material used must be load-bearing and non-combustible. As support, mounting components of steel cable support system are a good choice:
- Suspended supports with brackets
- Profile rails with threaded rods
- Mounting rails
- Fire-tested anchors
The constructions are not defined exactly in the approvals. The load capacity of the above-named components was proven in the fire tests for electrical function maintenance, meaning that they have also proven themselves in practice for the support of insulation.
Insulation in system floors and underfloor ducts
Insulation must also be installed in system floors - cavity floors and raised floors. If underfloor ducts run beneath walls with a fire resistance period, insulation measures must be taken. Screed-covered underfloor ducts are insulated starting from the closest connection sockets, as the wall opening can no longer be reached directly due to the poured screed. The distances between the connection sockets are irrelevant. Of importance is the smoke gas-tight and fireproof closure, in order to prevent the spread of fire.
In the case of open ducts with freely-accessible wall openings, insulation can be placed directly in the duct.
If raised floors abut onto, for example, escape routes with poured screed, then there must be at least partial insulation beneath the smoke protection door or fire protection door. In most cases, the insulation can only be worked from one side. In these cases, the PYROCOMB Intube system, cable insulation with a half shell, can be used.
Building in old buildings
The following applies for ceilings in existing buildings and for wall constructions made of special components (e.g. sandwich elements): Insulation systems, tested and approved for this application, can be installed.
As these special tests rarely exist, insulation is used in accordance with the approvals, whose function is proven in soffits made of non-combustible materials, e.g. in lightweight partitions. Before mounting, clarify the application with a surveyor.
Cable bandages
To prevent the fire spread within fire sections, existing cable support systems are bandaged with a coated mesh, which restricts a cable fire to a local area. In many cases, the total of the routed cables represents a "fuse wire", which runs through the building. Particularly critical are rising sections, as the flames spread most quickly in a vertical direction. Bandaged cable bundles or rising sections do not burn over a great period of time and thus limit the damage.
Benefits of cable bandages compared to coatings
Frequently, cables are additionally given fire prevention coatings. The problem here is the major work of the wet application. In addition, it must be ensured that the dry layer thickness corresponds to the prescribed data. By contrast, bandages have the following advantages:
- Mechanically-applied coating guarantees the necessary dry layer thickness
- Dry routing
- Simple fastening and lock with tightening strap
- Simple retroinstallation through opening of the tightening straps (reusable)
- Easy to mount thanks to differently coloured surface
- Surface is PU-coated and washable
Testing of the cable bandages
Fire protection bandages are subjected to a cable bundle test on a vertically arranged test body. Here, a defined, approved burning height may not be exceeded during a certain period.
Special applications
Special applications for the cable bandages can be found in the fields of photovoltaics, wind power, tunnels, ship construction or in existing buildings, e.g. in wooden constructions in attics. Here too, the protection aim is: Prevent the spread of fires. Whether this is for personal protection or system protection depends on the appropriate installation.
Use in escape and rescue routes
Bandages are used in escape and rescue routes if
- Mounting of fire protection-classified suspended ceiling,
- Panelling with plates or
- The installation of a fire protection duct
is not possible due to local circumstances or insufficient space. In so doing, the bandages match the route of the previously-installed cables, which is not possible without additional work in the case of fire protection ducts. On account of the function and the proof of the fire behaviour, the cable bandage is often the last economic option.
CAUTION!
The cable bandages were originally developed in order to prevent fire spread within fire sections. The effectiveness of the fire bandage can therefore not be compared to the performance of a fire protection duct in escape and rescue routes.
Tutorials on the subject of insulation
Simply explained, comprehensively protected. Our tutorials explain exactly what is important with the first protection aim.
