A cable comprising at least one electrical conductor and at least one electrically insulating layer surrounding said electrical conductor, wherein the at least one electrically insulating layer comprises: (a) a thermoplastic polymer material selected from: at least one copolymer (i) of propylene with at least one olefin comonomer selected from ethylene and an a-olefin other than propylene, said copolymer having a melting point greater than or equal to 130°C and a melting enthalpy of from 20 J/g to 90 J/g; a blend of at least one copolymer (i) with at least one copolymer (ii) of ethylene with at least one a-olefin, said copolymer (ii) having a melting enthalpy of from 0 J/g to 70 J/g; a blend of at least one propylene homopolymer with at least one copolymer (i) or copolymer (ii); at least one of copolymer (i) and copolymer (ii) being a heterophasic copolymer; (b) at least one dielectric fluid intimately admixed with the thermoplastic polymer material; (c) at least one water tree retardant selected from ethoxy
