Permanently Mounted Devices for Electrical Safety – Comparing Absence of Voltage Testers (AVTs), Voltage Indicators, and Test Points

When maintenance needs to be performed on a machine or panel, electrical workers perform a strict NFPA protocol to ensure circuits are de-energized before work can begin. Permanently mounted devices like Test Points, often combined with Voltage Indicators, and Absence of Voltage Testers (AVT) promise to improve worker safety and save time in the process, but only one meets NFPA 70E standards. Let’s unpack why.

What is a Test Point?

Test Points are permanently mounted devices that aid in the measurement of voltage with a portable test instrument from the outside of an enclosure. They test at the point of the circuit where the test leads are installed and can be an excellent tool for troubleshooting, while keeping workers away from danger.

However, Test Points can be thought of as an extension of the circuit part, not the actual circuit part, introducing some uncertainty into the test process. They don’t have a feature to verify leads are connected to the source conductor, and some installations require fusing for overcurrent protection, which if open would return zero voltage even while energized. Should a lead come loose, it would also show a zero-voltage result.

What is a Voltage Indicator?

Voltage Indicators are permanently mounted devices that illuminate LED-style indicators when the presence of voltage is detected. Voltage Indicators can be a straightforward way to provide a visual warning when voltage is present but should never be used to verify the absence of voltage.

Several scenarios could cause a voltage indictor to not illuminate when equipment is energized. Like a failed LED, bad installation, or failed device. For example, consider a light bulb in your home. If the bulb is off, does that mean there is no energy in the socket, or did the bulb fail? It could also be caused by a loose connection. How do you know?

Because of these limitations, they are not test instruments and should not be used to verify the absence of voltage.

What is an AVT?

Absence of Voltage Testers (AVT) are permanently mounted test devices designed specifically to prove absence of voltage. Panduit invented the AVT category with the introduction of VeriSafe™ in 2017, changing the lockout tagout process forever.

AVTs do not require additional test instruments to verify an enclosure is de-energized. While traditional lockout tagout process times can vary, AVTs can cut the time to complete the NFPA 70E protocol from around 20 minutes to 10 seconds.

VeriSafe executes a multi-step process to confirm absence of voltage with the push of a button. It first verifies internal functionality and confirms proper installation, then tests voltage, reconfirms installation and internal functionality, and finally indicates a result. Allowing an electrical worker to safely open the panel without any additional steps.

UL 1436 outlines extensive requirements for AVTs to ensure the absence of voltage test function is fail-safe and reliable. Active indicators, built-in overcurrent protection, and SIL 3 reliability for all safety functions are some of the key features. Like Voltage Indicators and Test Points, AVTs will only test the point in the circuit at which the test leads are installed. Unlike the others, AVTs also confirm that test leads are properly connected as part of the automated testing process and return an error message if they are not.

It Comes Down to Safety

Accidents happen when processes are not followed. VeriSafe™ AVTs automation eliminates mistakes and removes the incentive to skip steps to save time. Voltage Indicators and Test Points help workers verify presence of voltage without entering an enclosure, but they provide a false sense of security when used for confirming absence of voltage. This is why NFPA recently clarified 70E standards to draw a clear distinction between where and how to use Test Points and AVTs.

VeriSafe has been installed in applications as diverse as manufacturing, data centers, and electric vehicles. To see how VeriSafe can benefit your business, visit www.panduit.com/verisafe.