Mailing List flyrotary@lancaironline.net Message #33999
From: Al Gietzen <ALVentures@cox.net>
Subject: RE: [FlyRotary] Re: What size CB or fuses.. EC 2 items..
Date: Mon, 16 Oct 2006 21:43:41 -0700
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>

David;

 

I had a 15 amp fuse (regular, not a slow-blow) open driving 3 coils on my 20B. It apparently happened during start. I now run 20A on the coil circuits, and 15A on the injector circuits (3 on each).  16 AWG wire.

 

Dale;

 

You may want to try a different font – for whatever reason your messages come up blank on my MS Outlook Express.  I can’t read them until I click to ‘reply’.

 

Al

 

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Dale Rogers
Sent: Monday, October 16, 2006 4:45 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: What size CB or fuses.. EC 2 items..

 

Dave,

   I'm not saying that you've said anything incorrectly, but you did
leave out a fairly important factor (as well as included a factor
that is often overlooked: length of the wire run.) A wise person
sizes the wire to carry at least 20% more current than the "run"
load of the device(s) it supports.  _Then_ size the breaker to
support the load *potential* of the wire, not the actual load. 
That's how one avoids "false" breaker trips.

Dale R.

David Staten wrote:

Then let me restate the question.. whats the minimum amount of current the device requires to function properly.. so that the fuse or breaker doesnt blow in normal operation... I can "protect" the wire with a 1 amp breaker just as easy as I can with a 10 amp breaker..  It makes a difference in that I have a truckload of 5 amp breakers readily available but have to purchase 10's or 15's.

Yea.,.. you say do not size the breaker according to the amp load.. only to protect the wire run. BUT... in a proper installation, the wire is sized according to the load carried over the distance carried.. so indirectly.. you DO size the breaker to the load (via the wire's capacity to carry current)...

Dave

 

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