Voltage testers check for difference in potential in electrical circuits. Measurement type and measurement range are the most important parameters to consider. There are three main measurement types: AC, DC, and AC / DC. For both alternating current (AC) and direct current (DC) voltages, the measurement range is the maximum voltage that instruments can measure. Low voltage testers are designed for applications with voltages ranging from 12 VAC to 90 VAC. These devices are used to detect the presence of AC voltages in thermostats, industrial controls, and irrigation systems. High voltage testers are designed for testing electrical equipment which operates at 600 V or higher for terminal-to-terminal operation, or 300 V or higher for terminal-to-ground operation. AC and DC power supplies with low voltage and high current are also considered to be high-voltage devices.  

Many voltage testers are capable of taking specialized electrical measurements. Audible continuity testers beep when their probes touch one another. Battery testers are designed to test battery operation. Continuity testers are designed to detect the completeness of circuits. Diode testers are used to test diodes, electronic components that conduct electricity in only one direction. Voltage testers which take peak spike measurements and maximum/minimum (max/min) readings capture voltage spikes as well as maximum and minimum voltage values. RTD testers are used to monitor resistance temperature detectors (RTD), devices which exhibit changes in resistance with changes in temperature. Voltage testers that can be used with thermocouples and transistors are also commonly available. True RMS devices measure root mean square (RMS) values. 

Recognized Standards for Safety and Performance

Many voltage testers bear quality marks and comply with recognized standards for safety and performance. CE Marking indicates that a voltage tester complies with the applicable requirements of relevant European Union (EU) directives which uphold national standards for health, safety, and environmental protection. Voltage testers that bear the CSA Mark are tested by the Canadian Standards Association (CSA) and meet relevant standards from organizations such as Underwriters Laboratories (UL). Recognized standards for safety and performance include the EU’s Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronics Equipment (WEEE) directives. IEC 61010 from the International Electrotechnical Commission (IEC) is another important standard.