What does the fire point of transformer oil indicate?

Fire point is the temperature at which oil vapors sustain combustion after ignition, higher than flash point. A higher fire point generally indicates improved fire safety margin under abnormal heating conditions, though it does not eliminate risk. Fire point helps compare fluids such as mineral oil, natural ester, synthetic ester, and silicone, and supports substation fire protection design. Operators use it alongside flash point, volatility, and containment and suppression measures to assess site risk and insurance requirements.