![]() Weather appropriate arc-rated gear as needed.Hard hat, safety glasses, hearing protection, and leather footwear.Rubber insulating gloves with leather protectors.Arc-rated faceshield and arc-rated balaclava OR arc flash hood.Arc-rated clothing (long sleave shirt, long pants).Incident energy exposures equal to 1.2 cal/cm2 up to 12 cal/cm2 Simplified PPE list based on NFPA 70E Table 130.5(G) In 2018, this arbitrary cutoff was removed from an informational note with the intent that great emphasis with respect to de-energizing is always necessary regardless of the energy being 4 cal/cm2 or 40 cal/cm2. In practice, 40 cal/cm2 was often the cutoff for “safe” work and the highest PPE incident energy level described in 70E until 2018. The second level is from 12 cal/cm2 up to 40 cal/cm2 ( or greater). The first level is from 1.2 to 12 cal/cm2. The Arc Flash Institute recommends most facilities consider a two-level PPE program as outlined in NFPA 70E Section 130.5(G) and Table 130.5(G). When working within the arc flash boundary, and when a risk analysis determines that there is a likelihood of occurrence of an arc flash event, then arc flash PPE shall be worn. ARCAD Arc Flash Analytic software automatically selects either IEEE empirical model or Lee method for arc flash calculations based on input system parameters.Arc flash personal protective equipment (PPE) is required by OSHA and described in NFPA 70E. For cases where voltage is over 15 kV, or gap is outside the range of the model, the theoretically derived Lee method can be applied. The IEEE procedure is valid for voltages ranging from 208V volts to 15kV with gap ranges between 3 mm. The equations are used to calculate the incident energy and arc flash boundary. IEEE Standard 1584 details the procedure and needed equations for arc flash calculations. The boundary is defined by NFPA 70E as the distance at which the worker is exposed to 1.2 cal/cm 2. ![]() In addition, a qualified person must accompany unqualified persons. Persons crossing into the arc flash boundary are required to wear the appropriate Personal Protective Equipment (PPE) as determined by calculating methods contained in NFPA 70E. In some instances, calculations may decrease the boundary distance. NFPA 70E also allows the AFB to be calculated. NFPA 70E establishes the default arc flash boundary at 4 feet for low voltage (< 600V) systems where the total fault exposure is less than 5000 amperes-seconds (fault current in amperes multiplied by the upstream device clearing time in seconds). The AFB is a safe approach distance from energized equipment or parts. The arc flash boundary is based on voltage, the available fault current and the time it takes for the upstream protective device to operate and clear the fault. The arc flash hazard analysis should determine the arc flash boundary (AFB) and level of personal protective equipment (PPE) that the worker must wear. It is important to note that conductors and equipment are considered live when checking for voltage while putting equipment in a safe work condition. Until equipment is placed in a safe work condition (NFPA 70E 2000 Part II 2-1.1.3), it is considered live. Also, NFPA 70E 2000 requires that before a worker approaches exposed electric conductors or circuit parts that have not been placed in a safe work condition, a flash hazard assessment must be performed. The limited, restricted and prohibited approach boundaries are based on the voltage of the energized equipment. There are three shock approach boundaries (limited, restricted and prohibited) required to be observed in NFPA 70E 2000. ![]() NFPA 70E has developed requirements to reduce the risk of injury to workers due to shock and arc flash hazards.
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