This essential safety toll is used to confirm the correct operation of voltage detectors and phasing testers that do not have a self-testing capability. When the verifier handle is depressed at the rate of 3 strokes per second, a piezo crystal generates a safety check voltage. This voltage, when applied to the tip of the detector, tests for integrity of the current path and proper operation of the indicators. A three-step procedure of testing the detector with the piezo verifier, using the detector to test for the absence of high voltage and then testing the detector again should be strictly observed in accordance with accepted operating procedures. Verifier can be used with single - and two-pole models.