This reference dataset describes four representative Norwegian radial, low voltage distribution systems operated at 230 V. The dataset was developed in the Norwegian research center CINELDI. The dataset is based on real Norwegian distribution systems but has been anonymized. There are four folders for the four different grids, "39_semi_urban_grid_reference_grid", "56_semi_urban_grid_reference_grid", "50_rural_grid_reference_grid" and "80_rural_grid_reference_grid". All of the folders contain seven CSV files: four grid data files and three load data files. Grid data files: "mpc_branch.csv" and "mpc_bus.csv" contain grid data in the MATPOWER format, "mpc_branch_extra.csv" provides additional information about the branches in the grid, and "mpc_base_mva.csv" gives the base power value of the grid (needed since the values in the other grid data files are given in per unit value). Load data files: "p_load.csv" and "q_load.csv" contain hourly active and reactive power, respectively, for all the load buses in the grid, and "load_bus_extra.csv" provides additional information about the load buses in the grid.