For historic buildings such as cathedrals, fire is one of the greatest dangers. The reconstruction costs following the damage caused by the fire at Notre Dame is expected to be in the tens of millions. In addition to these material costs, it is impossible to fully quantify the damage caused by the irretrievable loss of precious art and cultural artifacts.
The risks and costs for world heritage
Following the devastating fire in the Notre Dame Cathedral in Paris in April 2019, fire prevention measures at the landmark cathedral and UNESCO world heritage site in Aachen were placed under urgent review leading to the installation of new system with ABB technology.
Close to the German borders with Belgium and the Netherlands, the High Cathedral of Aachen previously only had a fire alarm system in the roof truss. The entire sanctuary with all its wooden pews, altars, and organ, as well as textile artifacts, had been largely unprotected. Given the lack of overall protection and the evident risks from fire shown in Paris there was an urgent need for action.
Source: Jörn Wolter / vor-ort-foto.de 
Source: Jörn Wolter / vor-ort-foto.de
Detection and prevention: offering a holistic protection concept
The authorities responsible for Aachen Cathedral’s upkeep decided on an innovative, high-tech new fire prevention system to protect the 1,200-year-old pilgrimage church and burial place of Charlemagne. This included an AI-based early detection system for potential fire sources in support of full renovation of the entire electrical installation, including the voltage distribution system. Critically, ABB’s Arc Fault Detection Devices (AFDD) were installed to prevent dangerous arcs that, due to electrical contact faults, can be possible causes of fire, as occurred at Notre Dame in 2019.
“To ensure maximum safety for the electrical supply in the dome, we decided on the reliable AFDD portfolio of our long-standing partner ABB,” reports Michael Wagner, head of the local contractor, Wagner & Müller in charge of the renovation and responsible for the design of the new voltage distribution and the construction of the distribution board in the cathedral.
Electrical sparking: an underestimated risk
“Our broad AFDD portfolio improves electrical safety thanks to automatic detection of fault arcs. This reduces the risk of an electrically ignited fire,” explains Tim Hippler, a regional ABB representative.
The phenomenon of electric arcs is visible from the crackling flying sparks on the overhead line of a tram. Generally, these arcs occur when there is insufficient distance or insulation between two electrical conductors with different potentials. This can also occur within electrical switching elements if, for example, two contacts do not separate quickly enough. Thermal wear or undetected material defects can also cause the insulating layer between live parts to lose its insulating effect over time. And even when an unnoticed arc fault in a piece of equipment does not immediately cause a fire, the resulting temperature peaks accelerate thermal wear, thus impairing the safe and reliable operation of the circuit component.
Increased safety: voltage, frequency, and current analysis
This makes permanent prevention across the entire electrical supply infrastructure essential. ABB’s AFDD technology continuously analyzes frequency, voltage, and currents to detect patterns that indicate an arcing hazard. In such cases, the affected components are shut down immediately. This significantly reduces the risk of electrically ignited fires due to malfunctions in the installation. At the same time, AFDD reduces the thermal wear of critical switching components: this not only improves their reliability, but also extends their service life, saving potential costs in the future.
For the new installation in Aachen Cathedral, the project planners selected various AFDDs with integrated miniature circuit breakers. In addition to preventing arcing faults, these flexible switching devices also protect against overloads and short circuits. With these components, the customer met both fire and plant protection in a cost-effective manner and without unnecessarily increasing the complexity of the infrastructure. All ABB models comply with the international standard IEC 62606 and meet the requirements of DIN VDE 0100-420 in the current version.
The initial work on new power and data cabling started in the summer of 2022, and the complete refit will be finalized in June 2023. The new fire protection system is financed by donations raised by the Aachener Karlsverein-Dombauverein and by a grant from the state of North Rhine-Westphalia.
