A method for enhancing the dielectric properties of an electrical cable having a central stranded conductor encased in a polymeric insulation. The cable defines an interstitial void space (v.sub.1) between the strands of the conductor. The volume (v.sub.2) of a dielectric enhancement fluid required to be absorbed by the cable to reach a predetermined level of dielectric enhancement is determined. The ratio of (v.sub.1 /v.sub.2) is computed. If the ratio of (v.sub.1 /v.sub.2) is greater than a maximum ratio of 1.4, then a quantity of the dielectric enhancement fluid is diluted with a sufficient quantity of a diluent to produce a mixture of diluent and dielectric enhancement fluid, such that when the volume (v.sub.1) of the mixture is supplied to the cable interior, the cable will have been supplied with a volume (v.sub.3) of the dielectric enhancement fluid within the mixture such that (v.sub.3 /v.sub.2) is less than 1.4. The diluent is substantially insoluble in the polymeric insulation, has a sufficiently low initial viscosity to enable introduction into the cable interior, and is miscible with the dielectric enhancement fluid.