Abstract: A planar electrical heating unit that is sufficiently flexible to be conformable to nonplanar surfaces such as the exterior of pipes and tanks. The unit is formed of plural layers. There are two glass fiber reinforced silicon rubber layers between which is sandwiched an electric resistance heater element. On one outside surface is adhesively secured an imperforate metal plate. Mounted to the plate is a junction box for electrical connections to the heating element and for ground connection to the metal plate. A thermoelectric sensor is housed within the junction box and serves to interrupt current to the heating element when a prescribed temperature has been reached. Adjacent the edge margins of the unit are a plurality of grommets which prevent delamination of the layers of the device and facilitate mounting the device to the exterior surface of a pipe, tank, or the like.