![]() ARCAD Arc Flash Analytic software automatically selects either IEEE empirical model or Lee method for arc flash calculations based on input system parameters. Select the arc flash label template that you want and click on the Print button. 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. Select the User-Defined Arc Flash calculation by selecting the User-Defined radio button and you will get the incident energy, flash protection boundary, and the hazard/risk level according to NFPA 70E with the version selected previously. 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. Revisions have been made to Table 130.5(C), which can be used to help estimate the likelihood of occurrence of an arc flash incident, including a new entry for the initial circuit breaker or switch operation and again after maintenance, as each has a higher likelihood of an arc-flash event. The limited, restricted and prohibited approach boundaries are based on the voltage of the energized equipment. Some Major Changes for NFPA 70E 2021 Edition. These risk assessments determine what activities are carried out. For equipment that has incident energy levels above 8 Cal/cm 2 after the incident energy reduction work has been completed in the previous step, carry out task-based arc flash risk assessments. ![]() There are three shock approach boundaries (limited, restricted and prohibited) required to be observed in NFPA 70E 2000. Reduce the arc flash incident energy levels (if >8Cal/cm 2 and reasonably practicable). NFPA 70E has developed requirements to reduce the risk of injury to workers due to shock and arc flash hazards.
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