Current leakage testers measure the amount of current that flows through a ground conductor. They include a measuring device or probe that connects to a conductive point, a voltmeter that displays root mean square (RMS) values, and a circuit with specific resistance and frequency characteristics. Current leakage testers are used during both normal and single-fault conditions in order to determine whether electrical devices pose a shock hazard. For medical devices and other specialized equipment, additional single-fault conditions may be required. Organizations such as the International Engineering Consortium (IEC) establish and maintain standards for acceptable levels of current leakage from different classes of devices.