[RE-wrenches] interrupting current calculations used to determine the interrupting of the AC equipment.

[Darryl Thayer]

The interupting rating has to do with the equipment.  Each piece of switch gear or breaker has an interupt rating.  The service from the utility is capable of delivering a certian amount of current under short circuit conditions.  In a large metro area like a downtown loop it may be 200,000 amps at a residenice it is typically less than 10,000 amps.  Most residenitial equipment is rated to interupt a short circuit current of 10,000 amps that would occur if a bolted short happened.  If the short circuit current exceeds the rating it is possible the equipment could explode and the current would keep flowing.  
 
When I was a young man I was working in downtown Mpls, a working man droped a wrench accross some 480 volt bus bars, the upstream switch gear exploded, the fuses may have opened but the current keep flowing the transformers blewup two men were killed,  the fuses could not interupt the about 200,000 amps  

From: James Rudolph <jamesrudolph99 at gmail.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Monday, October 3, 2011 12:53 PM
Subject: [RE-wrenches] interrupting current calculations used to determine the interrupting of the AC equipment.


Dearest Wenches,

    I received an e-mail from PE reviewing one of our projects to build, and this is what they wrote-

No
interrupting current calculations were included.  It is suggested the
utility company be consulted for available at the service entrance and these
values be used to determine the interrupting of the AC equipment.

Does any one out there have experience dealing with this issue, or have the ability to shed some light on this subject.

Many thanks in advance,

-- 
James B Rudolph
NABCEP Certified PV Installer



_______________________________________________
List sponsored by Home Power magazine

List Address: RE-wrenches at lists.re-wrenches.org

Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out participant bios:
www.members.re-wrenches.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20111003/4f9837d5/attachment-0004.html>