When discussing electrical safety, a question frequently asked by NETA technicians is, “When does troubleshooting end, and when does repair begin?” This question is often paired with, “What does 70E say about troubleshooting and repair?” We hope to make things clear for everyone in the field.
NFPA 70E definitions
To begin, look at the definition of “working on” (energized electrical conductors and circuit parts) in Art. 100 of the 2024 edition of NFPA 70E. It says, “Intentionally coming in contact with energized electrical conductors or circuit parts with the hands, feet, or other body parts, with tools, probes, or with test equipment, regardless of the personal protective equipment (PPE) a person is wearing.
“Informational Note: Examples of ‘working on’ can include but are not limited to diagnostic testing (such as taking readings or measurements of electrical equipment, conductors, or circuit parts with approved test equipment that does not require making any physical change to the electrical equipment, conductors, or circuit parts) and repair or physical alteration of electrical equipment, conductors, or circuit parts (such as making or tightening connections, removing or replacing components, etc.).”
A lot is going on in the above definition. The first sentence begins with “Intentionally coming in contact ….. with the hands, feet, or other body parts ….” So, in this definition, contact is not accidental, but intentional with any part of the body. This separates it from unintentional contact (incident) or any type of equipment failure. That sentence continues “with tools, probes, or with test equipment, regardless of the personal protective equipment (PPE) a person is wearing.” This makes it clear that using voltage testers or any other type of test equipment is included, and PPE doesn’t change this; you’re still working on energized electrical conductors or circuit parts. Many technicians believe that troubleshooting is not “working on.” Clearly, it is, and appropriate PPE is necessary.
The Informational Note states there are two categories of “working on”: 1) diagnostic testing; and 2) repair. Diagnostic is defined as “taking readings or measurements of electrical equipment, conductors, or circuit parts with approved test equipment that does not require making any physical change to the equipment.” This would include absence-of-voltage testing, troubleshooting, calibration, or voltage testing.
Again, PPE is mandatory because using voltage-rated probes on energized electrical equipment is not considered safe. There is an exception in Chapter 3 for laboratory work, but it would not apply to NETA-type testing and maintenance work. Article 350 applies to this work where a specifically trained and responsible person known as the Electrical Safety Authority (ESA) can make job-specific requirements that may be different than those found in Chapter 1.
The second category of working on (repair) is defined as “any physical change to the electrical equipment, conductors, or circuit parts (such as making or tightening connections, removing or replacing components, etc.).” We have seen many instances where this is misunderstood or just violated, especially during maintenance-type activities.
A troubleshooting case study
Here’s a true story. A job leader took an apprentice to a switchgear room where low- and high-voltage equipment was installed. He pointed out areas the apprentice was to avoid, such as the main incoming line compartment. He worked with the apprentice for some time cleaning low-voltage connection strips and the inside of the panels.
When the job leader was called away to another part of the job, he told the apprentice, “Don’t work on anything that looked hot,” and walked away. The apprentice continued to clean, tighten connections, and inspect the low-voltage control compartments. In each compartment, he used his voltmeter to determine whether the terminals were energized (Photo 1).
Then, the apprentice came to a compartment that contained 4,160V potential transformers. This compartment was marked “PT Compartment,” but it did not have a sign on it warning of high voltage. The compartment immediately below the PT compartment did have a “Danger High Voltage” sign on the top of its compartment door (Photo 2).
The apprentice opened the door without the warning label and attempted to test the terminals of the 4,160V PTs. There was no indication of danger to the technician (Photo 3).
As soon as the test probes touched the PTs, an arc flash occurred. The apprentice was fortunate, as he survived the incident, but he spent several days in the hospital’s burn unit. He could have very well died, as he was not wearing any PPE.
Photo 4 shows the aftermath of the PTs blowing up, while Photo 5 shows the low-voltage tester used to test 4,160V PTs — a catastrophic scene for sure.
This case history, “Who’s at Fault — Owner or Contractor?” was presented at an IEEE Electrical Safety Workshop by Joseph Andrews. It shows why the 70E definitions are so critical. What people don’t know, they don’t know. There is a ton of useful information contained in the Art. 100 definitions. You may feel there is no danger in using an insulated (or uninsulated) screwdriver to tighten connections or in using a voltage tester to perform absence-of-voltage testing. However, there could be danger lurking just around the corner.
Chapter 1, Art. 130, Sec. 130.2(C) provides exemptions to the use of an energized electrical work permit. The entire section is reproduced below:
“(C) Exemptions to Work Permit. Electrical work shall be permitted without an energized electrical work permit if a qualified person is provided with and uses appropriate safe work practices and PPE in accordance with Chapter 1 under any of the following conditions:
(1) Testing, troubleshooting, or voltage measuring
(2) Thermography, ultrasound, or visual inspections if the restricted approach boundary is not crossed
(3) Access to and egress from an area with energized electrical equipment if no electrical work is performed and the restricted approach boundary is not crossed
(4) General housekeeping and miscellaneous non-electrical tasks if the restricted approach boundary is not crossed”
Note that the first sentence says, “Electrical work shall be permitted without an energized electrical work permit if a qualified person is provided with and uses appropriate safe work practices and PPE in accordance with Chapter 1 under any of the following conditions.” The person must be qualified to begin with. Unqualified persons are not permitted to be near energized electrical conductors or circuit parts. Second, that qualified person must be provided with and use appropriate safe work practices and PPE. An unqualified person would not know or be able to determine what is appropriate. The person in the case history above could not determine those two things.
Conclusion
Supervisors at any level — whether it’s in their title or not — must not make assumptions about what a person knows or doesn’t know. They must ensure the technician’s safety.
Troubleshooting, testing, and even tightening connections are considered by many to be safe. The previous example shows how wrong that assumption can be — and it is not just apprentices who make that mistake. Troubleshooting the control power transformer on a 4,160V motor starter has caused many incidents. One technician told us how the guts of his Wiggy (he was pretty old) flew across a building, striking 15 feet high on the opposite wall. If that coil had hit him, he would have been severely injured or killed. With electricity, small mistakes can be painful or fatal.
Author’s Note: This article was originally written by James R. “Jim” White of Shermco Industries. We have taken Jim’s work, updated it, and offered this revision in his honor. Great job, Jimbo!
