Who's Responsible? Arc flash hazard warning and labeling, part 2

By Mark C. Ode | Jan 16, 2023
shutterstock / Mashikomo
My December 2022 article on the new text in 110.16(B) in the 2023 National Electrical Code covered the new arc flash labeling requirements for service equipment and feeders rated at 1,000A or more. 

My December 2022 article on the new text in 110.16(B) in the 2023 National Electrical Code covered the new arc flash labeling requirements for service equipment and feeders rated at 1,000A or more. This article provides more details on the change’s ramifications.

It is important to understand who is responsible for labeling and what happens if there is a change in the downstream design of the installation after the labeling is posted on the electrical equipment. These are crucial to compliance with 110.16(B) and requirements in Article 130 of the 2021 edition of NFPA 70E, Standard for Electrical Safety in the Workplace.

Let’s tackle the question of who is responsible for labeling. To understand this issue, review the NEC, NFPA 70E and NFPA 70B, Recommended Practice for Electrical Maintenance, and how each is associated with the others. 

NEC, 70E and 70B, oh my!

The NEC is a prescriptive code involving proper and safe electrical equipment installations and wiring for the practical safeguarding of person and property from electrical hazards. NFPA 70E provides safe work practices and areas for employees relative to the hazards from electricity use. NFPA 70B is a recommended practice that applies preventive maintenance for electrical, electronic and communication systems and equipment. 

These three documents work together to provide a safe installation (NEC), safe working environment (NFPA 70E) and proper maintenance of the electrical equipment (NFPA 70B). The documents are involved in who is responsible for the labeling, and ultimately the pertinent information on it. Either the electrical engineer who designed the system or the electrical contractor doing a design-build or installing the system will be responsible for the calculation for the arc flash label. Whoever has done the calculation will usually submit it to a municipal electrical plan reviewer or an electrical inspector responsible for reviewing proper compliance in NEC 110.16(B).

What’s in the codes?

NFPA 70E 110.5(B) requires “the electrical safety program to include elements to verify that newly installed or modified electrical equipment or systems have been inspected to comply with applicable installation codes and standards prior to being placed into service.” 

Section 110.5(C) in NFPA 70E also requires the electrical safety program to include elements that consider condition of maintenance of electrical equipment and systems, since lack of proper maintenance of overcurrent protective devices will affect the opening time.

In addition, 130.5(H) in NFPA 70E requires equipment labeling. Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures and motor control centers in locations other than dwelling units likely to require examination, adjustment, servicing or maintenance while energized must be marked with a label containing the following information: the nominal system voltage, arc flash boundary and at least one of the following: (a) available incident energy and the corresponding working distance, or the arc flash PPE category in Table 130.7(C)(15)(a) or Table 130.7(C)(15)(b) for the equipment, but not both; (b) minimum arc rating of clothing; or (c) site-specific level of PPE.

Additionally, 130.5(H) states “the method of calculating and the data to support the information for the label must be documented and reviewed for accuracy at intervals not to exceed 5 years. Where the review of the data identifies a change that renders the label inaccurate, the label must be updated.” 

Who is actually responsible?

So ultimately, the electrical equipment’s owner is responsible for the documentation, installation and maintenance of the marked label. Any changes to the system would require updating the labels.

If an EC were successful in the bid for a project, and the design contract didn’t require the engineer to calculate the label information for 110.16(B), then the contractor and owner will be responsible.

Let’s also say that the electrical contractor is only responsible for the 1,000A or greater service and feeders, and the owner installs major motor loads after the contractor’s label was installed. The motor contribution of that load could cause an increase in the amount of available fault current and could invalidate the incident energy value shown on the label installed by the contractor. An inaccurate level of PPE could be a major safety issue. The owner of the electrical equipment is required by the last paragraph in 130.5(H) in NFPA 70E to update the label and may not know or understand this problem. Make sure everyone involved in these types of projects is aware of all of these important safety issues.

Header image source: Shutterstock / Mashikomo

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]





featured Video


New from Lutron: Lumaris tape light

Want an easier way to do tunable white tape light?


Related Articles