This guide covers general recommendations for loading mineral oil-immersed, 55°C rise, step-voltage and induction-voltage regulators manufactured in accordance with ANSI/IEEE C57.15-1986. Some users may choose to load regulators as though rated for 65°C rise, although this operation is not recognized by ANSI/IEEE C57.15-1986. This guide treats the loss of life to be anticipated under such operation. Loading recommendations in tabular form are contained in this guide. These recommendations cover a wide range of ambient conditions and loss of life. The method and equations used for calculation of the tables are given. This guide is only applicable for regulators having inherent capability to permit the loadings covered.