The Absence of Voltage Tester (AVT) is a relatively new innovation. As we see it, it’s a new approach to an old problem.
Unlike traditional voltage testers, the AVT is not portable. It is installed in the equipment it is testing. An AVT can be used to determine if and when a circuit part is de-energized prior to opening doors and removing covers from electrical equipment. An AVT will automate the functions of handheld voltage testers for this specific task and will display information about the status of voltage inside equipment without exposure to electrical hazards.
AVTs are entirely different in function, and far more comprehensive than voltage indicators. Although they are both permanently mounted devices, voltage indicators merely provide a visual representation when voltage is present, they are not capable of testing for, nor indicating that, a de-energized condition exists. For instance, if a voltage indicator is not illuminated, it may be because the system is de-energized, but it could also be due to a device failure, an installation failure (if the device becomes disconnected from the wiring, it will not detect voltage), or an indicator (e.g., LED) failure. These are some of the reasons permanently installed voltage indicators were never recognized by OSHA as an alternative to the voltmeter test.
The shortcomings of permanently installed voltage indicators helped bring attention to an industry need and led Panduit create a new and innovative product. An AVT now provides a quick and reliable means of verifying the absence of voltage – a big win on safety and time savings for the electrical worker.
AVTs are defined in a new product listing category that was added to UL 1436, the Standard for Outlet Circuit Testers and Similar Indicating Devices, in September 2016. With the addition of these new requirements, products can now be listed and labeled as an absence of voltage tester. AVT listing requirements were brought about by research presented at the 2016 IEEE Electrical Safety Workshop on electrical injuries that occurred while voltage testing. Because there were no installed devices designed specifically to test for the absence of voltage, unique listing requirements for such a product were not addressed by standards for other product categories. Recognizing this, UL set out to define requirements and identify the best place to publish them. Ultimately, UL 1436 was selected because its scope included other installed testers and it could be revised in a timeframe that coincided with the NFPA 70E 2018 revision cycle, which was also considering provisions for AVTs.
Today, the AVT is truly a new approach to an old problem – and, it’s one that enables user to comply with the new requirements for verifying the absence of voltage in the 2018 edition of NFPA 70E.