This unit is a water resistant switching type voltage converter intended for use on vehicles with hazardous loads such as petroleum with a 24V electrical system to power an independently isolated 12V supply of either polarity. This unit is based on the proven AMI24-12-5 with a higher isolation capability and approved 1K grounding resistor. The unit can deliver 5A continuous and 6A intermittent output load current and has output overload and over temperature protection with a fully automatic reset. The combination of switching converter and linear out put regulator provides a low noise output closely regulated against variation of input voltage and changes in output load current. The unit provides total galvanic isolation of the 12V output from the 24V input. The unit is assembled in an aluminium extruded case and encapsulated in silicone rubber. This allows reliable operation in harsh vehicle environments and areas of high ambient temperatures.