A Pb-free Sn-based material part of a wiring conductor is provided at least at a part of its surface, and the Sn-based material part includes a base metal doped with an oxidation control element. A vertical support is attachable to the back end of the base. , a permanently magnetic grid, which defines a plurality of openings. Such an arrangement allows for better monitoring of the user’s vicinity in an emergency situation without the need for prolonged user participation in narrating or describing the emergency situation. The input of the converter is connected to the second signal input.