Electrical apparatuses and a method for their production, the apparatuses containing electrical insulation fluids comprising polytrimethylene homo- or copolyether glycol having a dielectric breakdown voltage greater than about 30 kV, wherein from about 50 to 100 mole percent of the repeating units of the polytrimethylene homo- or copolyether glycol are trimethylene ether units. An electrical insulation fluid comprising (a) polytrimethylene homo- or copolyether glycol having trimethylene ether units at about 50 to 100 mole percent of the repeating units and (b) a blending component selected from the group consisting of vegetable oils, mineral oil, poly alpha olefins, synthetic esters, and silicone fluids, and mixtures thereof, wherein the electrical insulation fluid has a dielectric breakdown voltage of greater than about 30 kV.