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.
Why Use Permanently Mounted Electrical Safety Devices to Verify the Absence of Voltage?
Compared to the conventional method of absence of voltage testing inside an electrical cabinet— assuming the system is still energized—these devices provide a much safer alternative to verify the absence of voltage as outlined in the both Article 120.5 (7), of NFPA 70E, 2018 and OSHA 29 CFR 1910.333(b)(2)(iv)(B).
Per NFPA 70E, there are six risk control methods that are required to be implemented per Article 110.1(H)(3). Risk Control Hierarchy (RCH) classifies risk controls in six categories:
• Engineering controls
• Administrative controls
The controls must be applied in order of priority, with elimination as highly effective to PPE as least effective. The purpose of the RCH is to identify and apply a single or combination of risk control methods that are suitable for the specific application and the task performed. Permanently mounted electrical safety devices fall under the engineering controls category within the RCH. NFPA 70E realizes that there is no one-size-fits-all solution as it relates to applying risk controls across a wide variety of tasks performed. Furthermore, when it comes to electrical safety, there is no such thing as absolute zero risk. The same is outlined in the NFPA 70E handbook as failure modes associated with every type of risk control method along with examples.
When it comes to electrical safety, there is no such thing as absolute zero risk. Using any permanently mounted device for absence of voltage testing at the door still begs the question of failure modes in terms of device functionality, wiring, workmanship, worker qualification, training and physical damage to the device itself. These failure modes are common with any product such as an Absence of Voltage Tester or a Test-Point using an adequately rated portable test instrument with test probes.
Importance of Worker Qualification & Training
As we know, there are several failure modes that exist with every product from design through installation and operation, so it is equally important to know the effect of those failure modes on both the worker and the task performed. Per NFPA 70E, Article 110.4 (A), only qualified persons shall perform the absence of voltage testing. A qualified person is one who knows what steps must be taken if the absence of voltage cannot be verified from outside an electrical cabinet.
It is imperative to note that safety is a condition of being protected from the risk of injury or hazard and is not something that can be attained by just installing a device at the door. Furthermore, workers’ confidence plays a significant role when it comes to safety, as safety is very personal. The simplest way to look at is this: a facility owner/operator can enforce that their workers don a higher amount of PPE for a task at hand and make them comply. However, for the same task, one cannot enforce compliance of lower amount of PPE when the worker realizes it provides less protection or feels unsafe to do so. Installing a permanently mounted device for absence of voltage testing outside the door is similar in that way. A facility can install a permanently mounted test device on the door for absence of voltage testing and ask their worker to perform the task, as it greatly reduces the risk of both shock and arc flash hazards. At the same time, one cannot stop their electricians to reverify the circuit part inside the cabinet with a portable test instrument even after the system is deenergized. It is that extra measure of reverification that adds confidence to the safety of the worker.
Maybe over a period of time and the development of confidence, the same worker will choose not to reverify the circuit part inside the cabinet, but it takes time to develop that trust—as with any device. Portable test instruments and accessories have built that trust and demonstrated confidence with absence of voltage testing for over four decades through several iterations of use. In conclusion, determining a right product fit for absence of voltage testing is a key step in your electrical safety program. A facility must perform a thorough risk analysis to figure out that right product/application fit. The detailed analysis must consider worker qualifications, installation conditions, training and failure modes of the products and further evaluate the effects of those failure modes on your application.
The qualified worker community has built trust and confidence with portable test instruments and accessories for decades with absence of voltage testing, and that trust cannot be simply replaced overnight.