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ARC FLASH IN LOW VOLTAGE MAIN BOARD

Former Community Member
Former Community Member
Hi eveyone ! 


I was wondering if there is a conservative table out there that tells which PPE you should use depending on the voltage, normal current, and shortcircuit perhaps of the place you are working.. 


Specially this is because of a new installation, which will have a main circuit breaker of 2000A, in 400V with a three phase shortcircuit fault of aprox 30KA at the point of the main CB.


When we energise for the first time, what type of PPE should we use ? I have been reading and depends on the cal/m2 but perhaps there was a rapid conservative table or experience of yours to tell what type of PPE we should use 


Also, the main circuit breaker is inside the gabinet, and has no dead front to cover the cooper busbars, they are covered in the front with transparent acrylic (6mm depth), in order to prevent to touch them. So to turn on the MCB we have to do it with the gabinet open
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    You can't base it on the voltage, normal current, SCC, etc. because each installation can be different. The arc flash energy depends on the voltage, arc current and time (duration) of the arc, so normal current is essentially irrelevant, but even voltage and SCC alone don't necessarily give the right answer as the clearance time of the breakers/fuses is important and a current just below the instantaneous tripping time of a breaker can give a higher arc flash energy than the full short circuit current.


    Reading your description of the cabinet, I would not be particularly happy working with that arrangement and my best advice would be if possible arrange for remote switching from the other side of the room (or preferably from a completely different room!)


    Alasdair
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    You can't base it on the voltage, normal current, SCC, etc. because each installation can be different. The arc flash energy depends on the voltage, arc current and time (duration) of the arc, so normal current is essentially irrelevant, but even voltage and SCC alone don't necessarily give the right answer as the clearance time of the breakers/fuses is important and a current just below the instantaneous tripping time of a breaker can give a higher arc flash energy than the full short circuit current.


    Reading your description of the cabinet, I would not be particularly happy working with that arrangement and my best advice would be if possible arrange for remote switching from the other side of the room (or preferably from a completely different room!)


    Alasdair
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