A continuity tester can be used to test if two points are electrically connected together. For this purpose, a safe voltage is generated by a battery which is built-into the device. If the current flows unrestricted, either a lamp lights up or an acoustic signal transmitter provides information on the status. Newly installed lines in production, on construction sites or in buildings can therefore be reliably tested. Voltage testers determine DC or AC voltages and also their value, depending on the model. While contactless testers can only detect AC voltages, devices with contacts are also able to measure DC voltage. Testers of this type are used as test equipment in switch cabinets, electrical outlets or device outputs.