According to Article 110.16 of the 2020 NEC, switchboards, switchgear, panelboards, industrial control panels, meter socket enclosures, and motor control centers that are in other than dwelling units, and are 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. A warning tag will need to be on each switchboard, panelboard, industrial control panel, and motor control center. The tag will say “WARNING Arc Flash and Shock Hazard Appropriate PPE Required”. The tag will need to have the following information: • Flash Hazard (Protection) Boundary – The Flash Protection Boundary is the distance at which the incident energy level equals 1.2 cal/cm 2 . For situations where fault clearing time is 0.1 second (or faster), the Flash Protection Boundary is the distance at which the incident energy level equals 1.5 cal/cm 2 . • cal/cm 2 Flash Hazard at 18 inches • PPE Level – Type of clothing required. The proper hazard identification and use of PPE is referenced in NFPA 70E-2021 Table 130.7(C)(15)(a) entitled “Arc Flash PPE Categories for Alternating Current (ac) Systems”, Table 130.7 (C)(15)(b) entitled “Arc Flash PPE Categories for (dc) Systems”, and Table 130.7(C)(15)(c) entitled “Personal Protective Equipment (PPE)”. Please refer to these charts for more details. Consult with FR (flame-resistant) manufacturers to determine performance of specific FR clothing systems. • Shock Hazard when Cover is Removed – Typically the voltage of the equipment. • Limited Approach Boundary – An approach limit at a distance from an exposed live part within which a shock hazard exists. For a person to cross the Limited Approach Boundary and enter the limited space, a person should meet the following criteria: 1. Have an energized electrical work permit authorized by management. 2. Be able to identify the hazards and associated risks of the tasks to be performed. • Restricted Approach Boundary – An approach limit at a distance from an exposed live part within which there is an increased risk of shock, due to the electrical arc over combined with inadvertent movement, for personnel working in close proximity to the live part. To cross the Restricted Approach Boundary and enter the restricted space, qualified persons must do the following: 1. Have a plan that is documented and approved by authorized management. 2. Use personal protective equipment (PPE) that is appropriate for working near exposed energized conductors or circuit parts and is rated for the voltage and energy level involved. 3. Be certain that no part of the body enters the prohibited space. 4. Minimize the likelihood of bodily contact with exposed energized conductors and circuit parts from inadvertent movement by keeping as much of the body out of the restricted space as possible and using only protected body parts in the space as necessary to accomplish the work.
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