Fuses vs. Breakers (was QO Breakers and Panels)[RE-wrenches]

[Drake Chamberlin - Electrical Energy]

<x-flowed>In Denver, we are required to put fuses ahead to the breaker in certain 
high fault current situations.  If the transformer is large enough and the 
run of wire is short enough, fuses are required.   This is usually only 
required for commercial installations.

Drake

At 01:29 PM 03/08/2001 -0800, you wrote:
>I'm  not the best qualified person on the list to discuss this but I wanted
>to get this out so perhaps the less experienced Wrenches could get
>introduced to this.  Then perhaps some else could elaborate on my following
>generalization.
>
>A very general statement is...
>
>Fuses are for stopping faults before they do a lot of damage and breakers
>are for over current protection.  Faults and over current are very different
>things.  A fault on a system with more the just a few golf cart batteries
>will have catastrophic results.
>
>
>Last year I attended a 4 day electrical course given by the local utility
>company.  A rep. from Cooper/Bussman and Square D each had about 1/2 day
>each to present to us.  The Copper/Bussman rep. had some really, really neat
>videos.  He showed what happens to a breaker when it gets hit by a large
>(20,000 amp or better) fault.  It exploded and took out the bulk of the
>enclosure with it!  It looked like a grenade went off.  There was 4/0 THHN
>wired to the breaker and it whipped around like #14 SO cord in the wind.  It
>would have killed the unlucky fellow who caused the fault.  Kinda makes you
>think about being plumber after watching the video.  Then they put the fuse
>to the same test, it stopped the fault with no fanfare.  I bet we could get
>these guys to do a presentation at the next MREF.  Cooper/Bussman is out of
>St. Louis.  It is a very informative session designed for the installing
>electrician type.  It had a little marketing fluff but not much.
>
>So what is the implication?  It is a very good idea to have a fuse in
>between the batteries and the breaker.
>
>Travis Creswell
>Ozark Solar
>
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For info contact list moderator by email:
 michael.welch at homepower.com

____________________________________________________________
T O P I C A  -- Learn More. Surf Less. 
Newsletters, Tips and Discussions on Topics You Choose.
http://www.topica.com/partner/tag01

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