A seal is used to prevent the escape of gas from a gas pressurized plastic-jacketed, multi-conductor cable where the conductors of an unjacketed portion of the cable enter a cabinet of a terminal which is exposed to temperature cycling. The seal includes a sleeve made of an elastomeric material having one end which engages an end section of the cable jacket with the conductors of the unjacketed portion of the cable extending through the other end of the sleeve into the cabinet. The seal also includes a metallic tube which is disposed about the elastomeric sleeve with one of the end portions of the tube which is aligned with the cable jacket being in compressive engagement with the sleeve and jacket. A plugging compound in the other end portion of the tube and which is compliant with the sleeve material encapsulates the conductors and the other end of the sleeve which extends into the plugging compound. The compliancy of the sleeve and the plugging compound cause them to move together during temperature cycling to avoid the development of leak paths and the escape of gas from the cable.