Switching Arc flash

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a 480 volt switchgear , distribution panel, requiring category-4 arc-flash protection.


circuit breakers primary defense against current runaway, if there no secondary fuses, if arc flash develops in breaker there may nothing stop flash going out of control. once arc flash begins in breaker, can migrate single circuit busbars of panel itself, allowing high energies flow. precautions must used when switching circuit breakers, such standing off side while switching keep body out of way, wearing protective clothing, or turning off equipment, circuits , panels downline prior switching. large switchgear able handle high energies and, thus, many places require use of full protective equipment before switching 1 on.


in addition heat, light , concussive forces, arc flash produces cloud of plasma , ionized particles. when inhaled, ionized gas can cause severe burns airways , lungs. charged plasma may attracted metallic objects worn people in vicinity, such earrings, belt buckles, keys, body jewelry, or frames of glasses, causing severe localized burns. when switching circuits, technician should take care remove metals body, hold breath, , close eyes. arc flash more form in switch closed slowly, allowing time arc form between contacts, more desirable throw switches fast motion, , firmly making contact. high-amperage switches have system of springs , levers assist this.








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