The analysis shall determine the Flash Protection Boundary and the personal protective equipment that people within the Flash Protection Boundary shall use.” This is outlined by NFPA 70E - 2004, Electrical Safety Requirements for Employee Workplaces, states, “A hazard analysis shall be done in order to protect personnel from the possibility of being injured by an arc flash. This explosive energy is measured in calories/cm2. conversions: 1 inch = 25.4 mmm and 0.24 cal/cm 2 = 1 Joule/cm 2Ĭontact Omazaki Consultant if you are looking for consultant services for studying and assessing the hazards and risks of arc flash, especially to calculate the incident energy generated by potential arc flash on your electrical system throughout Indonesia.NFPA 70e calculations are necessary to properly determine the explosive arc flash energy level of a worker who could be exposed.t = arcing time in seconds from overcurrent device time current curve. E B = incident energy at the arc flash boundary, typically 1.2 cal/cm 2 or 5 Joules/cm 2.It is always better to place the equipment in an electrically safe condition and not to perform live work. Work performed within the AFB requires adequate PPE based on NFPA 70E requirements. This boundary is typically calculated as the distance where the incident energy falls off to 1.2 cal/cm 2. The Arc Flash Boundary (AFB) known as Flash Hazard Boundary in IEEE 1584, is defined as an approach limit at a distance from exposed live parts within which a person could receive a second degree burn if an electrical arc flash were to occur. The clearing time is normally determined from the upstream protective device’s time current curve using the estimated arcing current. The second equation is used to adjust the normalized data to specific conditions. The first equation is used to determine the incident energy based on a normalized working distance of 24 inches and a clearing time of 0.2 seconds. The distance from the source is referred to as working distance. Incident energy is defined as the amount of energy impressed on a surface at a certain distance from the source. The next step is to calculate the incident energy in calories/cm 2 (cal/cm 2). I bf = bolted short-circuit current (kA)įactors for Equipment and Voltage Classes.k = – 0.153 for open air and – 0.097 for arcs in a box.The formula or equation for estimating arcing short-circuits based on IEEE 1584-2002 is as follows:
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