NEC Section 110.16 is all about warning the qualified electrician about the potential of an arc-flash hazard and has nothing to do with Available Fault Current (AFC).

Section 110.16(A) requires electrical equipment, such as switchboards, switchgear, panelboards, industrial control panels, meter socket enclosures, and motor control centers, in other than dwelling units, that is likely to require examination, adjustment, servicing, or maintenance while energized, to be field or factory marked to warn qualified persons of potential electric arc flash hazards. The marking must meet the requirements in 110.21(B) and shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.

It is important to distinguish between the rules in 110.16 and 110.24 and understand that they each have a different purpose. Section 110.16 warns of the potential arc-flash hazard which is the first step in realizing that additional safety measures might be required before the electrician considers opening the energized equipment.

Section 110.24 requires the amount of AFC to be marked on the service. This AFC value is not used to select the proper level of personal protective equipment (PPE) and has nothing to do with working on energized equipment. The AFC value is used when selecting proper equipment ratings for circuit breakers and other equipment that the service supplies power to.

See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on the “free access” tab and select the applicable year of NFPA 70 (National Electrical code).

2020 Code Language:

110.16 Arc-Flash Hazard Warning.

(A) General. Electrical equipment, such as switchboards, switchgear, panelboards, industrial control panels, meter socket enclosures, and motor control centers, that is in other than dwelling units, and is likely to require examination, adjustment, servicing, or maintenance while energized, shall be field or factory marked to warn qualified persons of potential electric arc flash hazards. The marking shall meet the requirements in 110.21(B) and shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.

2023 Code Language:

110.16 Arc-Flash Hazard Warning.

(A) General. Electrical equipment, such as switchboards, switchgear, enclosed panelboards, industrial control panels, meter socket enclosures, and motor control centers, that is in other than dwelling units, and is likely to require examination, adjustment, servicing, or maintenance while energized, shall be field or factory marked to warn qualified persons of potential electric arc flash hazards. The marking shall meet the requirements in 110.21(B) and shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.