A control unit for an elevator installation comprises a cover and a base. 5 or higher, with the proviso that non mono-lower alkyl ethers or phenyl ethers or benzyl ethers of diethylene glycol, wherein the lower alkyl is of 2 to 6 carbon atoms, are present in said composition. Support structures including air as a dielectric can be provided in the form of printed circuit boards and electrical connectors. The call is then transmitted to a second network element, operating on a second operating protocol, wherein the same universal call identifier is accepted by the second network element. The mounting brackets include L-shaped slots for slideably receiving vertical bolts of the floor maintenance machine.