ARCAD Arc Flash Analytic software automatically selects either IEEE empirical model or Lee method for arc flash calculations based on input system parameters. 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. ESUK can help you to limit this scope by applying our knowledge and experience of which parts of your network will be higher hazard, and which parts will be low hazard. The boundary is defined by NFPA 70E as the distance at which the worker is exposed to 1.2 cal/cm 2. Calculate the Arc Flash Incident Energy Levels and Arc Flash Boundary Distances on each piece of equipment that is connected to your Electrical Distribution Network. 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. Simply put, the arc flash boundary is the distance at which an electrical arc can flash/expand outward, which may endanger employees working on electrical equipment. 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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