A substrate installation unit for installing with other substrate installation units, in particular of the same type, for covering a substrate, wherein the substrate installation unit comprises a substrate-side attachment structure, which is designed for attaching to the substrate; and a plug connection structure, facing away from the substrate, for releasably plug connecting, in particular with a formation of a snap-in plug connection with a correspondingly designed plug connection structure of a surface installation unit, which comprises a utilization structure.