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EXP-Bus Safety?

Subject: EXP-Bus Safety?
From: Robert L. Nuckolls III <RNuckolls@compuserve.com>
Date: Sat, 7 Jun 1997 14:32:25

 /I have been trying to follow this thread over the last 
 /weeks, and the more I follow, the more confused I get.  
 /Initially it appeared to me that the ExpBus was a great thing, 
 /even if a little expensive.  It appears now, after following your 
 /answers that every feature on it has drawbacks that would make 
 /it even dangerous to use.

   It DOES have some safety issues but by-in-large, I'll suggest
   that it's worst sins are that it's less than truthful in
   its promotion.  You're correct, $250 is a pretty good chunk
   of change.

 /Because you have the experience and knowledge that you have, 
 /why don't you design something similar using your approach to 
 /parts and construction, that can be built by us.  It could 
 /even be packaged with instruction and parts.  

   I'm not sure anything needs to be fabricated by me or
   anyone else to provide a more acceptable alternative to
   wiring an airplane. If one purchases a battery master relay
   (mounted where it belongs  . . . right next to the battery)
   a couple of Bussmann 15600 series fuse blocks (mounted under
   the panel where ever you would have mounted the remote EXP-Bus
   board) and the toggle switches (mounted where the EXP-Bus 
   switches would have been mounted) that you'll have exemplary
   protection, convenience and very nearly an exact duplicate
   of the EXP-Bus remote mounted wiring task.  Assuming:

                            Fuse Block     Breakers     Fab/Install
                                                          Estimate

     Battery Contactor:        $20             $20           1 hr
     Breakers (30)                             600          16 hrs
                                                      Fab, Assemble & Wire
     Fuse Blocks (2):           60                           1 hr
     Fuses (30):                 7
     Switches (10):             57              57           3 hrs           
     Terminals (56):             6               6           2 hrs
     Assted Wire between
      protection and switch      5               5           
                              _____           ____
                              $155            $688

   These times are estimates of how long it would take me
   to fabricate switch and breaker panels and do drawings for
   purchase of engraved overlays. The fuseblock installation 
   saves you $100 over EXP-Bus and $530 over breakers. Except
   for the fabrication of bus bars and breaker panels, either
   installation presents no bigger a wiring task than the remote 
   mounted EXP-Bus installation and the values I've give above
   allow for up to 30 protected circuits.  Further ALL parts
   are off-the-shelf distributor items available from dozens 
   of sources. This is another plus for rolling-
   your-own that I'd not thought of before. Except for the
   Bussmann fuseblocks, there are NO proprietary fabricated
   parts and lots of alternatives for sources. Bussmann stands
   a VERY good chance of being around for awhile. So . . .
   future repairability and cost of ownership of the parts-built
   system are quite attractive.


 /I'm not very good at electronics even though I have a degree 
 /in Office Machine Repair and worked at the trade for about 7 
 /years.  Replacing parts was one thing, but designing circuits 
 /was something else, and now, I'm going to be "designing the 
 /circuits in the GS.  The simplicity of just connecting to the 
 /ExpBus was what cought my eye.  

   It was your relative inexperience in designing and fabrication
   that hooked you. If someone hands you a relatively complex
   looking piece of stuff and says, "lookee here at all the time
   and effort I can save you by doing this in advance and handing
   it to you as a completed assembly."  What the offeror doesn't
   tell you is that all the custom assembly work may not be necessary
   or is easily replaced by machine fabricated parts using other
   sources and technologies.

 /Anyway, I'll keep following the thread, maybe things will eventually 
 /fall into place when I start wiring......I'm sure thankful there 
 /are people on the net like you and the others.  Keep up the good work.

   Thank you. Again, I'll point out to folk following this thread and
   others. My mission is to discover and then share the most cost
   effective ways to accomplish a task with NO compromises in performance
   or safety.  Airplanes are an EXPENSIVE hobby. I believe that if
   we all put our heads together and figure out how to trim unnecessary
   time, cost and weight out of the more traditional techniques, 
   you'll stand a better chance of having more time, dollars and/or
   panel space to install something that enhances the utility of your
   airplane.

    Regards,

    Bob . . . 
    AeroElectric Connection
                   ////
                  (o o)
    oOOo(_)oOOo
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    |  Go ahead, make my day . . .  |
    |   Show me where I'm wrong.    |
    


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