The test instrument or loop resistance meter is used for non-contact testing of ground resistance in electrical installations. The tester with self-luminous inverse LCD display, simultaneously displays resistance (0.010 - 1200 ohms) and AC current (0.00 mA - 20.0 A), and has a measurement data memory, adjustable alarm function when limit is exceeded, automatic shutdown and data hold function. The rugged instrument has a wide measuring range with high resolution, accurate, reliable and stable performance, and high noise immunity. The tester is microprocessor controlled and provides accurate ground resistance measurement. The integrated filter technology effectively minimizes measurement noise. The structure of the product conforms to protection class 2 and is double or reinforced insulated.