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arodri04
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Post subject: Can we use a maintenance switch with a 800A CB? Not according to Annex O.2.3  Posted: Thu Aug 16, 2012 10:29 am |
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Joined: Thu Oct 27, 2011 5:28 am
Posts: 2
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I was under the impression we can use maintenance switch to reduce arc flash temporarily but then Annex O.2.3 says it has to be a breaker rated for 1000A or more. Why would that be? and would I be breaking code if I use it on my 800A breaker.
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FGuillenS
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Post subject: Posted: Thu Aug 16, 2012 10:49 am |
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Joined: Fri Mar 16, 2012 7:14 pm
Posts: 7
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Annexes are not part of the code.
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Vincent B.
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Post subject: Posted: Thu Aug 16, 2012 11:48 am |
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Joined: Tue Feb 24, 2009 7:05 am
Posts: 252
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I read at as if your CB is rated 1000 A or more, then it must be equipped with one of the 3 items.
If your CB is rated lower, then it's not mandatory per the informative Annex O, but nothing prohibits you from implementing one of those items.
Also, in CSA Z462, there's a fourth item: arc flash detection relay.
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Zog
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Post subject: Posted: Fri Aug 17, 2012 8:54 am |
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Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
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I agree with Vincent, and have installed several maintenence switches on 800A breakers. Just not required but still a great way to reduce Ei for maintenence tasks.
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arodri04
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Post subject: Posted: Mon Aug 20, 2012 8:09 am |
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Joined: Thu Oct 27, 2011 5:28 am
Posts: 2
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I am glad to hear it is still ok... we are using the maintenance switch to mitigate arc flash ratings and this section on Annex O was not clear to me. Thanks.
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Terry Becker
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Post subject: Posted: Mon Aug 20, 2012 8:43 am |
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Joined: Sun Sep 23, 2007 5:00 pm
Posts: 148
Location: Calgary, Alberta, Canada
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The 1000A is irrelevent and will be removed from the Annex. There is reference in NEC with respect to HRGs systems. You will also see other engineering safety by design solutions added as the existing language didn't consider all options, the language was submitted by a particular equipment manufacturer that did not have other options like arc flash relays, HRG etc.
Regards;
Terry Becker, P.Eng.
[url="http://www.esps.ca"]www.esps.ca[/url]
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