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Arc Flash Hazard Warning and Labeling: What the 2023 NEC has to say on these requirements

By Mark C. Ode | Dec 15, 2022
stock.adobe.com / Seetwo
Arc flash hazard warning and labeling has been in the NEC for a number of cycles and is relatively easy to implement.

Arc flash hazard warning and labeling has been in the NEC for a number of cycles and is relatively easy to implement. This necessary warning label provides a reminder of PPE’s importance when working on energized electrical equipment and the extreme hazards present. When I first started working in the electrical construction industry in 1971 and even into the 1990s, PPE was in its infancy. We were lucky to have voltage-rated gloves for shock protection. The sophisticated PPE available on the market these days is a miracle of innovation and design.

Staying safe

The major steps taken in the NEC and NFPA 70E in the past few cycles emphasize the partnership between the two major safety documents in the electrical industry. The design and installation requirements in the NEC have helped improve safety for those working on electrical equipment. New sections in the past few cycles, such as 240.67 covering arc energy reduction for fuses rated at 1,200A and higher, and 240.87 covering arc energy reduction for circuit breakers rated at 1,200A or higher, provide installation requirements and safer equipment that work hand in hand with NFPA 70E.

Addressing the clearing time of fuses and circuit breakers by using different installation methods for reducing available arcing fault current will save many from severe burns and possible loss of life. We all must work diligently toward the goal of reducing to zero the major arc flash events that face all of us when working on live equipment. We must wear our PPE when working on procedures resulting in an electrically safe work condition or on live equipment and fill out an energized work permit for one of the four reasons provided in 110.4(A) through (D) in NFPA 70E. Employees must also be cognizant of any present and future changes in the NEC that may affect our electrical installations and understand their ramifications.

Past and future requirements

One change in the 2023 NEC may not be recognized as a major issue until we analyze the text and think how the change will affect many installations. The major change is actually in 110.16(B), but let’s go back to the text inserted into a new 110.16(B) in the 2017 NEC. The new text reads: “In other than dwelling units, in addition to the requirements in 110.16(A), a permanent label shall be field, or factory applied to service equipment rated 1200 amps or more. The label shall meet the requirements of 110.21(B) and contain the following information: Nominal system voltage; available fault current at the service overcurrent protective devices; the clearing time of service overcurrent protective devices based on the available fault current at the service equipment; the date the label was applied.” 

The new exception is “Exception: Service equipment labeling shall not be required if an arc flash label is applied in accordance with acceptable industry practice.”

This new section required the EC to install this label with the available fault current and reaction time of the overcurrent protective device for services rated 1,200A or more and a calculation date.

The new text in the 2023 Code is as follows: “110.16(B) Service Equipment and Feeder Supplied Equipment. In other than dwelling units, in addition to the requirements in 110.16(A), a permanent arc flash label shall be field or factory applied to service equipment and feeder supplied equipment rated 1,000 amperes or more. The arc flash label shall be in accordance with applicable industry practice and include the date the label was applied. The label shall meet the requirements of 110.21(B).”

This change requires the electrical contractor to provide an arc flash label (based on 130.5(H) in NFPA 70E, including arc flash boundary and one of the following: available incident energy, arc flash PPE category, minimum arc rating of clothing, or site-specific level of PPE for any service or feeder rated 1,000A or more at time of installation.

Inserting this into 110.16(B) makes the authority having jurisdiction directly responsible for approving this application. Part of the arc flash calculation is the total available fault current, including motor contribution. This could become an issue for an EC that is only installing the basic electrical system and the tenant improvement involves the owner of the industrial or manufacturing equipment. This might involve a contract exclusion or some other method of dealing with who is responsible for this label. More on this subject next month.

About The Author

ODE is a retired lead engineering instructor at Underwriters Laboratories and is owner of Southwest Electrical Training and Consulting. Contact him at 919.949.2576 and [email protected]

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