Light in the dark

Small distribution boards in the Dechen Cave

Sensitive electronics frequently reach their limits at an air humidity level of almost 100 %. Small distribution boards from Spelsberg also keep them safe and prevent condensate under such extreme conditions in the Dechen Cave in Iserlohn.

Even 148 years after its discovery, the Dechen Cave in Iserlohn still draws 60,000 visitors per year.

“We equipped the entire cave in LED technology in the winter 2014/15,” explained Thomas Warnke, who works as an electrician for MVG, the local transit authority that supplies electricity to the cave. All of the system cables were replaced in the course of this project. Thick cable harness between 25 distribution boards and numerous spotlights in the cave were replaced with modern bus technology. Therefore, wiring work was drastically reduced and the numerous relays in the distribution boards could switch modern electronics, which also reduced spatial requirements.

There were now special requirements for the distribution boards in light of the high-quality electronics. The small distribution boards that were previously used, brand products of good quality throughout, in which condensate water accumulated regularly were no longer sufficient.

“We have an air humidity of almost 100 % at a temperature of 10 degrees Celsius in the cave – however only inside. At the entrances, these conditions vary depending on the outside temperature so that we have humid summer days with high amounts of moisture due to condensing water,” explained Dr Stefan Niggemann, Managing Director of the cave and the connected German Cave Museum.

There was the additional problem that the lighting of the cave is only switched with great irregularity. During open hours, it is continuously activated – then switched off again for hours at night. As a result, the distribution board interior space normally heats up, then cools down again and draws damp cave air into the interior. With the existing water-tight, but not gas-tight enclosures, this moisture remained in the interior and increased over time – an unsustainable status for the responsible persons which entailed exorbitant maintenance and service.

It was during this phase that Spelsberg introduced its new AK Air distribution board to the market. Alexander Schmidt, Spelsberg employee, arrived to open doors with his customer Thomas Warnke.

The key features of these enclosures integrated air ventilation elements – a world first, which finally reliably prevent the formation of condensation inside the distribution board by enabling a permanent exchange of pressure and air. Air flowing in during the cooling process can escape again easily with the moisture during the subsequent heating process. 

The ventilation elements are designed so that water and foreign objects are unable to penetrate into the interior thanks to their special shape. As a result, the protection rating IP 65 can be assured in spite of the permanent exchange of air.