The requirement for electrical installations with function maintenance is part of the construction regulations. Regulations require a power supply to be assured for a specific period of time, even if there is a fire.
Emergency lighting, smoke extractors, and alarms must remain operational for at least 30, 60 or 90 minutes, according to requirements, so people can leave the building and rescue forces can work.
Junction boxes must be verified with EN 60670 conformity. This includes environmental requirements, such as moisture, protection from dust and environmental temperature, corrosion and mechanical stress, as well as electrical testing conditions. In order to meet fire protection requirements, electrical installation systems must operate for 30, 60 or 90 minutes and withstand temperatures of up to 1000 °C, according to DIN 4102-12.
Function maintenance tasks:
Function maintenance for a safe evacuation and rescue –
For buildings to be cleared quickly, function maintenance must be guaranteed e.g. for the following equipment:
- Safety lighting systems
- Lifts with fire control
- Fire alarm systems
- Alarm systems and systems to issue instructions
- Fire extraction systems
Function maintenance for effective fire-fighting –
To support fire-fighting operations, it is important that technical equipment is supplied with sufficient power, even up to 90 minutes after a fire breaks out. This equipment includes:
- Water pressure increase systems for the fire water supply
- Mechanical smoke extraction systems and smoke protection pressure systems
- Fire brigade lifts
Burn test according to DIN 4102-12
The aim of the burn test is to validate the correct operation of the electrical system and to ensure that the critical services, such as emergency lighting and fire alarm systems, remain functional for long enough to organize a rescue in the event of a fire.
The German standard DIN 4102-12 specifies that the complete system of cable trays, accessories and cables must be tested in an oven for a period of 30, 60 or 90 minutes, up to a temperature of 1000°C.
The set-up before the burn test
Cables and wires with intrinsic fire resistance are installed on the ceiling and vertically and horizontally on the wall, whereby each line includes a cable junction box with terminals. The ends of each cable are placed through the wall of the oven and then connected to electrical test circuits from the outside.
The burn test
After completing the installation, the oven is closed and fired up. Within minutes, the ambient temperature will rise, based on the pre-determined temperature curve according to EN 1363-1.
The plastic junction boxes melt within a few minutes. Shortly after, the cables burst with actual fire. The ceramic terminals ensure the continuous flow of current.
The test continues for up to 90 minutes.
The burners are closed. The temperature has reached 1000°C.
After the test
According to DIN 4102-12, the test is passed if the circuit is not disrupted for a fixed period of 30, 60 or 90 minutes.
Even though the plastic enclosure has melted, the current is still flowing.
Metal enclosures and ceramic terminals remain in good condition.