A cable (1, 17, 31, 39, 47, 55, 59, 63) for conveying radiofrequency and/or microwave frequency energy to an electrosurgical instrument at a first end of the cable, the cable comprising: a hollow tube comprising inner (5, 19, 33, 43, 49) and outer (9, 23, 37, 45, 53) electrically conductive layers separated by dielectric material (7, 21, 35, 41, 51) to form a transmission line; a first terminal at the first end of the cable for forming an electrical connection to the inner conductive layer (5, 19, 33, 43, 49); a second terminal at the first end of the cable for forming an electrical connection to the outer conductive layer (9, 23, 37, 45, 53); a rotatable component (69, 75, 81, 91, 95) at the first end of the cable, wherein the rotatable component comprises a longitudinal passageway continuous with the hollow tube, wherein the hollow tube and the passageway are configured to provide liquid, gas and/or components to the electrosurgical instrument, and wherein the rotatable component is rotatable relative to the transmission line and comprises: a first portion (71, 79, 85, 91a, 99) electrically connected to the first terminal, wherein the first portion and the first terminal are rotatable relative to each other and are configured to maintain an electrical connection when rotated relative to each other; a second portion (73, 77, 83, 91b, 97) electrically connected to the second terminal, wherein the second portion and the second terminal are rotatable relative to each other and are configured to maintain an electrical connection when rotated relative to each other. a hollow tube comprising inner (5, 19, 33, 43, 49) and outer (9, 23, 37, 45, 53) electrically conductive layers separated by dielectric material (7, 21, 35, 41, 51) to form a transmission line; a first terminal at the first end of the cable for forming an electrical connection to the inner conductive layer (5, 19, 33, 43, 49); a second terminal at the first end of the cable for forming an electrical connection to the outer conductive layer (9, 23, 37, 45, 53); a rotatable component (69, 75, 81, 91, 95) at the first end of the cable, wherein the rotatable component comprises a longitudinal passageway continuous with the hollow tube, wherein the hollow tube and the passageway are configured to provide liquid, gas and/or components to the electrosurgical instrument, and wherein the rotatable component is rotatable relative to the transmission line and comprises: a first portion (71, 79, 85, 91a, 99) electrically connected to the first terminal, wherein the first portion and the first terminal are rotatable relative to each other and are configured to maintain an electrical connection when rotated relative to each other; a second portion (73, 77, 83, 91b, 97) electrically connected to the second terminal, wherein the second portion and the second terminal are rotatable relative to each other and are configured to maintain an electrical connection when rotated relative to each other. a first portion (71, 79, 85, 91a, 99) electrically connected to the first terminal, wherein the first portion and the first terminal are rotatable relative to each other and are configured to maintain an electrical connection when rotated relative to each other; a second portion (73, 77, 83, 91b, 97) electrically connected to the second terminal, wherein the second portion and the second terminal are rotatable relative to each other and are configured to maintain an electrical connection when rotated relative to each other.