House pickups are powered from the building's main switchboard via internal power lines (wiz), from which branches are made to individual apartments. Branches from internal supply lines to flats and non-residential premises are made on • individual floors on floor boards. Multi-storey distribution boards are usually placed in distribution and meter sets installed on the landings of staircases, in recesses secured with steel doors.
Internal power lines are routed:
— w budynkach wznoszonych metodami tradycyjnymi — w specjalnych kanałach instalacyjnych;
— w budynkach wielkoblokowych, large-panel and monolithic - in installation channels made of prefabricated building elements;
— w budynkach wysokich — w specjalnych szybach instalacyjnych.
Visas are not allowed in lift shafts.
The number of internal supply lines depends on the number, the power and layout of the apartments. The visas can be made single-phase, if it is to supply a maximum of two consumer installations. If there are more apartments, internal power lines should be made as three-phase and connected in such a way, that the loading of the phases is even. The cross-section of the internal supply lines must not be less than 4 Mm2 Cu, and for visas intended for one or two recipients, the cross-section must not be less than 2,5 Mm2 Cu. Only cables with a rated voltage of not less than 750 V. The cross-section of the internal conductors of the power lines should be the same along the entire length.
Branches from internal supply lines to the flats should be run in sheathed insulating pipes under the plaster with single or multi-core cables or in plaster with flat cables with plastic insulation. Branches are usually made single-phase. In the case of apartments, with high-power receivers (electric cookers, water heaters), three-phase branches are used. The cross-section of conductors for branches from visas must not be less than 2,5 Mm2 Cu.
Residential distribution board; F - fuse, W·h - electric energy meter, W — installation switches, l — residual current circuit breaker.
Each branch is secured and equipped with an electricity meter. Branch protections are placed on the floor board directly at the branch point. Electricity meters should be placed in a uniform manner for the entire building, In multi-family buildings, they are placed in closed cabinets on staircases.