Misconceptions on Absence of Voltage Testing
When it comes to electrical safety, there is no such thing as absolute zero risk.
- By Bhanu Srilla
- Feb 02, 2021
Absence of voltage testing is the most vital step in the process of verifying and establishing a deenergized state of any electrical system. According to the Article 120.5, NFPA 70E, it is a process-oriented approach that takes various steps to establish a deenergized state. It is not accomplished with any single device. Verifying a deenergized state is another risky task which requires strict adherence to policies and procedures to establish a safe environment to work. Because it is a high-risk task, verifying a deenergized state requires strict adherence to policies and procedures.
Additionally, it is also a regulatory requirement per OSHA’s 29 CFR 1910.333 (b)(2)(iv)(B) and NFPA 70E, Article 120.5. Historical data suggests high incident rates of both shock and electrocution because of performing the task of absence of voltage testing inside the electrical cabinets. The data further points out that the incidents are primarily caused due to workers’ inadvertent contact with electrical circuit parts inside the panel, wrong application of test instruments, human error, production pressures and complacency.
Many safety centric organizations and product innovators have devised a variety of methods to minimize the risk of exposure to workers from the hazards of presence and absence of voltage testing over the past several decades. In its recent edition, NFPA 70E, 2018 allowed an alternative method through a new exception for the same task under the Article 120.5 (7). This document delineates the differences between presence and absence of voltage testing from the application standpoint of lockout/tagout and compares the pros and cons of these devices and their limitations of use. Products discussed include voltage indicators, test portals, permanently mounted accessories, portable test instruments and absence of voltage testers. Given the process-centric approach, additional clarification is placed on worker qualification, installation conditions, training requirements, procedures and failure modes of these risk control methods and their effects on both the task and the worker.