Racking and unracking breakers on metal clad switchgear 1kV to 38kV ranks as one of the riskiest activities a worker can perform on electrical equipment. Even with closed doors, workers are required to wear personal protective equipment (PPE) in the event that an arc flash explosion were to occure. The worker in this CCTV clip should have been wearing a much higher level of PPE than he was since the cabinet was opened and he was exposed to energized electrical conductors and circuit parts.
The core of the arc flash can reach temperatures of 35,000 degrees F, which instantly turns copper conductors to a plasma state, causing the copper to expand 67,000 times its size in a fraction of a second. The rapid expansion brings molten shrapnel on a pressure wave of thousands of pound per inch. The closest approximation would be 3 sticks of dynamite exploding within 2 feet from the worker. And because the severity of the arc is fed by current and cycles before interruption, low voltage applications can be stronger than high voltage.
For more information on arc flash, electrical safety and infrared windows, visit www.iriss.com.
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