The major proportion of available flammable materials in energy research facilities consists of the coverings and insulations for electrical conductors in control, power, and diagnostic circuits. Since quantitative information on flammability of insulations is sparse, we initiated a program to investigate these properties. Our objective is to develop data applicable to predictions of fire risk parameters for large experimental energy facilities and, ultimately, new power generating plants. Our procedures involve measuring evolution of corrosive products as well as other thermal degradation products in air and nitrogen. We use a thermogravimetric analyzer to study effects of heating rate on modes of degradation and a heat release rate calorimeter to survey effects of thermal irradiance levels on product generation and the heat release rate of insulation materials. Thermal measurements—heat release rate, flame spread rate, and ease of ignition—show that common insulating materials are not easily ignited and that they burn with relatively little heat output and slow flame spread. However, when conditions are right, thermal rate parameters can interact to produce intense, fast-moving fires. Such conditions occur where the surface-to-volume ratios of conductors are great, enhancing both fuel availability and heat feedback from flames. In large energy research and production facilities, this condition is common.