We studied fire properties of MOF(Metering Out Fit) insulation cover and field condition of 22.9kV power receiving system. $49.5\%$ of formal equipments were installed indoors, whereas $40.8\%$ of informal equipments were installed as H-type. Insulation treatment was not done at a $22.4\%$ ratio of main line($27.7\%$ of transformer, $70.2\%$ of COS, $10.4\%$ of MOF). Fire pattern analysis showed that the fire started at the secondary part of OC wire. In the result of DTA(Differential Thermal Analysis), normal cover showed exothermic reactions at $310^{circ}C,;399^{circ}C;and;510^{circ}C$ (endothermic reactions at $382^{circ}C$). Whereas damaged cover showed exothermic reactions at $412^{circ}C$(endothermic reactions at $389^{circ}C$). In the result of TGA(Thermo Gravimetric Analysis), the thermal weight change of normal cover was similar compared to damaged cover. In the result of FT-IR analysis, normal cover showed absorption peaks at $3,024cm^{-l},;2,921cm^{-l},;1,600cm^{-1},;1,492cm^{-1},;1,451cm^{-1},;1,154cm^{-l},;1,027cm^{-1},;906cm^{-1}$. Whereas, in case of tracked cover, the absorption peaks that were shown in normal cover disappeared and different absorption peak was shown at $966cm^{-1}$