The IRS2 is designed to overcome the problem of high resistance error and tests for reference electrode contact resistance, validating the accuracy of a field reading. The IRS2 switch is a portable push button device which momentarily changes the input impedance of the digital multimeter. This feature permits the Corrosion Technician to detect high resistance in the external circuit, such as faulty test lead connections or high resistance contact between a reference electrode and the electrolyte.

The “normally-open” switch means the IRS2 can be left plugged-in without changing the meter's characteristics, but reduces meter input resistance significantly when the push button is depressed. If there is ±5% (or more) difference in the displayed reading, then there is a contact resistance error that requires correction.

Using the IRS2 during potential surveys enhances performance by reducing the number of inaccurate readings. True potential values may be calculated in areas with very dry, frozen, or high resistivity soil.