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 Post subject: PPE level
PostPosted: Wed Sep 16, 2009 2:58 pm 
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Joined: Sun Nov 16, 2008 12:01 pm
Posts: 44
Can main switch gear 3000 amp @ 480 volt be operated and if so what level ppe be required? There are 600 amp cb here and i have the same question. Maybe it is not enough info . i,ll take a good guess. Thanks to all


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PostPosted: Wed Sep 16, 2009 4:30 pm 
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Joined: Mon Jun 02, 2008 11:58 am
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Location: Charlotte, NC
PUCKMAN wrote:
Can main switch gear 3000 amp @ 480 volt be operated and if so what level ppe be required? There are 600 amp cb here and i have the same question. Maybe it is not enough info . i,ll take a good guess. Thanks to all


Can it be operated, sure. What PPE is required depends on the available fault current and clearing time of the upstream protective device. You need to provide more info, if you are going to "guess", guess a 40 cal/cm2 flash suit.


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PostPosted: Tue Sep 22, 2009 12:37 am 
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Joined: Thu Jul 19, 2007 7:54 am
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Location: St. Louis, MO
3000A / 480V Switchgear is likely fed from ~ a 2500kVA transformer. It is doubtful, on a transformer that size that you would be able to coordinate the upstream protection well enough to get the energy level below 40 cal/cm2 at 24" at the main breaker. The energy level is probably closer to 100 cal/cm2. Without a main in a separate compartment, the whole switchgear is likely over 40 cal/cm2. The energy levels below a main breaker will depend on how conservatively you are able to set the protection.

Unless you have some supplemental protection, it is unlikely that you should work on the switchgear.


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PostPosted: Tue Sep 22, 2009 2:19 am 
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There are mitigation solutions for everything but without applying these methods WdeanM is right on the mark.


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PostPosted: Sat Sep 26, 2009 12:36 pm 
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thanks to all the replys . the service is 4000a 480v secondary feed from 6 500kva trans. 13 kv prmary.


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