Abstract: A flexible electric heater may be formed from multiple congruent planar layers secured to one another to form a laminate in a variety of configurations. A junction box is adhered to the planar layers over an opening in an outer layer. An adhesive catchment area in the laminate is filled with adhesive, and the adhesive extends into the junction box where it fills a second adhesive catchment area. The mass of continuous adhesive thus formed seals and bonds the junction box to the flexible planar layers. Conductors from the electrical heater pass through the adhesive and may be strain relieved.