A universal mounting system for insulated instruments includes a mounting plate which engages openings in mating parts of a self-supporting insulated enclosure. The plate supports the instrument and the enclosure independently and allows all connections to the interior of the enclosure to be made through the plate. The plate is bent to an L-shape, with one leg supported by a support structure and the other leg supporting the instrument and enclosure. A termination of a traced tubing system is housed in an enclosure mounted to an opposite side of the mounting plate. The mounting plate includes a collar, cutouts in mating sections of the enclosure fitting over the collar to mount the enclosure to the mounting plate. Illustratively, the mounting plate includes a mount plate portion connected to a supporting structure, and an instrument plate mounted to the instrument.