Polymer concrete electrical insulation including a hardened epoxy resin composition filled with an electrically non-conductive inorganic filler compositions. The polymer concrete electrical insulation system optionally may contain additives. The epoxy resin composition is based on a cycloaliphatic epoxy resin. The inorganic filler composition can be present within the range of about 76% by weight to about 86% by weight, calculated to the total weight of the polymer concrete electrical insulation system. The inorganic filler composition includes a uniform mixture of (i) an inorganic filler with an average grain size within the range of 1 micron (μm) to 100 micron (μm) [component c(i)], and (ii) an inorganic filler with an average grain size within the range of 0.1 mm (100 micron) to 2 mm [component c(ii)]. The inorganic filler with an average grain size within the range of 1 micron (μm) to 100 micron (μm) [component c(i)] can be present in an amount within the range of 22% to 42%, calculated to the total weight of the polymer concrete electrical insulation system; and (e) the inorganic filler with an average grain size within the range of 0.1 mm to 2 mm [component c(ii)] is present within the range of 41% to 61% by weight, calculated to the total weight of the polymer concrete electrical insulation; and method of producing said electrical insulation.