A tap-switching autotransformer for regulating the voltage supplied to a facility includes an electronics sub-assembly for controlling switching of the taps. The electronics sub-assembly and the windings are contained in a housing from which the electronics sub-assembly may be removed for repair or replacement. The electronics sub-assembly is adapted to enable an electronically actuated switch to short-circuit two of the taps. A mechanical switch enables a separate short-circuit to be maintained between the taps to enable the electronics sub-assembly to be safely removed from the housing.