Voltage Tester for Working at Height We have a selection of voltage testers that let you safely check the efficiency, durability and working conditions of lots of different electrical appliances when working at height. And they are an invaluable tool for workers involved in a wide variety of construction-based industries. Our voltage tester lets you quickly check voltage levels of AC and DC circuits and determines both short and open circuits. And, you can efficiently hunt out polarity issues and test for the presence of live volts. While the inclusion of a handy clip lets you tether the voltage tester to a harness or work belt – ideal for working at height.