Abstract: An electrical resistance and insulation tester providing a 12 volt D.C. and a 500 volt D.C. testing circuit. Indicating means are comprised of an incandescent bulb for the 12 volt D.C. test circuit and a neon bulb for the 500 volt D.C. test circuit. A 12 volt D.C. power input circuit and a 110 volt A.C. power input circuit provide for operation at either input. The tester also comprises a chargeable capacitor circuit that allows for testing when the instrument is not connected to any power input source.