Thru-Panel Voltage Detection Fits NFPA 70E and CSA Z462

Thru-Panel Voltage Detection Fits NFPA 70E and CSA Z462

By Philip Allen, Grace Engineered Products

Workplace electrical safety has found its way into every facet of our electrical world. Manufacturers eagerly seek design changes in electrical world. Manufacturers eagerly seek design changes in electrical equipment that are more compatible with NFPA70E/CSA Z462 standards. Maintenance departments need to keep equipment running, so they look for smarter, safer and more productive ways to do so. Amidst this swirling change and the rising tide of electrical safety, thru-door voltage detection floats to the top every time. Here is why:

Keeping personnel away from live voltage is foundational to electrical safety. More importantly, electrical safety demands a precise answer to the question, "Is voltage present?" Thru-panel voltage detectors go a long way in providing the very first answer to this all-important question, while a voltmeter provides personnel with a second, redundant answer. Voltage detectors also provide visibility of voltage from outside the enclosure without exposing personnel to the hazard. Surprisingly, those using thru-panel voltage detection on their equipment have found this concept to be overwhelmingly embraced by all levels of maintenance people.

"Supervision is seeing the value of using panel voltage detectors. It is my opinion that your process of eliminating the exposure is much more achievable than changing a culture," says Mike Murphy, NECA-IBEW Senior Trainer.

The principles for creating an electrically-safe work condition are found in NFPA 70E 120.1. Chart 1 shows how each of these principles finds a home with different features and functions of the VoltageVision indicator and ChekVolt portal.

Is a thru-panel voltage detector a safety device or just another electrical gizmo? The answer is both. These below-listed principles teach us how these simple devices become effective safety tools for reducing risk to workers.

Training and Written Lock-out Tag-out (LOTO) Procedures: A thru-door voltage detector used in a safety program must be written into the LOTO procedure [NFPA 70E 120.(C)(2)]. Employees must be trained in using voltage detectors [NFPA 70E 110.6(D)(4)(e)].

Increase Productivity and Safety with Mechanical LOTO: Workers performing mechanical LOTO (work involving no contact with conductors or circuit parts) procedures must isolate electrical energy. Externally-mounted voltage detectors provide a means of checking voltage inside an electrical panel. Without these devices, a mechanic performing mechanical LOTO would be required to work in tandem with an electrician using a voltmeter to physically verify voltage inside an electrical panel. In this case, the electrician is exposed to voltage. With thru-door voltage detectors, the mechanic can single-handedly check for zero electrical energy without any exposure to voltage.


Reduced Voltage Exposure and Arc Flash Risk: Voltage is the common denominator in an electrical accident or an arc flash. No voltage means no accident, no arc flash. Electricians performing electrical LOTO with a thru-panel voltage detector installed, reduce risk because they are able to pre-check the internal voltage state without opening the enclosure. Next, they open the panel to replicate a zero energy reading with their voltmeter as per NFPA 70e 120.1.(5). Because of the lessened risk of voltage exposure, some will conclude that once the panel is open the need for personal protection equipment (PPE) is also reduced. Whether or not you agree with this, voltage detectors are a low-cost, redundant voltage verification tool that reduces arc flash risk, increases safety, and adds productivity for an installed cost of $150.

Using voltmeters to check for voltage on live incoming disconnects creates an opportunity for an arc flash. High incident energy (Category 3 & 4) panels further intensify this danger. Safety is a natural byproduct when voltage detectors pre-checks voltage before an electrician performs his voltmeter check.

Stored Energy Detector: The NFPA 70E recognizes the danger of induced voltages or stored electrical energy [NFPA 70e 120.1(6)]. Since stored energy shows up as AC or DC voltage, a voltage indicator alerts personnel to it presence.

Visible Blade' Disconnect: For disconnects or circuit breakers without visible blades, a voltage detector is able to confirm that the blades are fully open. "Wherever possible, visually verify that all the blades...are fully open" [NFPA 70e 120.1(3)].

As an electrical gizmo, these additional benefits create even more value for users.

Permanent Device: Unlike a voltmeter, a voltage detector is a permanent part of an electrical system. A voltage indicator has the ability to continuously check voltage between each phase and ground, thereby creating a safer environment for maintenance workers. A voltage indicator is maintenance-free because it receives its power from the line voltage, not from batteries. Permanent voltage detectors are less prone to damage because they cannot fall out of a tool belt like a voltmeter.

Fuse Status & Power Indicator: Under NFPA 70E, checking fuses or verifying system power requires workers to wear proper personnel protective equipment in addition to performing their LOTO procedure. Having fuse and power status information readily available with a voltage indicator on the outside of the electrical enclosure has proven to eliminate reasons for workers to access the enclosure.

Labels for each Voltage Source: By wiring voltage detectors to every voltage source inside an enclosure, an electrician immediately knows the location and number of voltage sources feeding the enclosure.

Those who work in the automation world need electrical safety, and the NFPA 70E and CSA Z462 go a long way to providing a safe work environment. Before thru-door voltage checking, companies had to sacrifice productivity for the sake of electrical safety. Now, by incorporating voltage detectors, employees working on machines can do so with confidence. Design changes are equipping those machines with reliable devices that are compatible with NFPA 70E and CSA Z462, and eliminate exposure to dangerous voltage is proofing to be a leading force in changing a culture.

About the Author: Philip Allen is President of Grace Engineered Products.

Grace Engineered Products is the leading innovator of thru-door electrical safety devices, and ships products all over the world including Asia, Australia, Europe, and North and South America. GracePort, their brand of PLC ports, has revolutionized the automation industry by allowing customers to custom-design their port to meet their specific needs. Grace Engineered Products is a privately owned company and located in Davenport, Iowa.