ANSWER: Not necessarily. For example: Small fractional KVA transformers use the class 105°C insulation system, which is 55°C rise. The class 150°C insulation system, which is 80° C rise, has generally been superseded by a class 185° C insulation system, which is 115° C rise. Medium KVA size transformers, approximately 371/2 KVA and larger, are generally manufactured using a 220° C insulation system, which is 150° C rise. All of these insulation systems from 105° C through 220° C will normally have approximately the same number of years operating life. A well designed transformer, observing these temperature limits, should have a life expectancy of approximately 20-25 years.