There is no clear answer to this question, but, if the cabinet is more than 20-25 years old, it has no doubt reached the end of its useful life. Of course, an old cabinet can also withstand a fire but, as is the way of the world, the insulation material changes and the protection deteriorates over time, making it impossible to say whether a 30-year-old cabinet will withstand a fire with the same degree of security as one that is 5-years-old!
