Methods and devices related to multi-layer tubular conduit are disclosed. The method of making the multi-layer tubular conduit includes providing a hermetically sealed metal tube, inserting a thermoplastic conduit within the tube, and surrounding the exterior of the tube with an overjacket. The multi-layer tubular conduit device includes three layers: a layer of thermaplastic conduit, a layer of hermetically sealed metal tube, and a layer of overjacket. The three layers are arranged coaxially such that they share a common central axis. The method of use includes installing a multi-layer tubular conduit device in a public or non-public environment. The multi-layer tubular conduit offers mechanical protection from harsh and/or hostile environments while still offering the flexibility of traditional conduit.