Mailing List flyrotary@lancaironline.net Message #33994
From: David Staten <Dastaten@earthlink.net>
Subject: Re: [FlyRotary] Re: What size CB or fuses.. EC 2 items..
Date: Mon, 16 Oct 2006 16:36:35 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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

Tracy Crook wrote:

Answer to this one is always the same :  Size the breaker to protect the wire size used.  The device hooked to the wire has nothing to do with breaker size.
 
The 40 amp breaker example in the installation guide was to illustrate the importance of having separate main branches of the electrical system, one for flight critical systems and one for other stuff.  I got a call last week from a builder who lost his engine on final on his first flight when he turned on his landing lights.  Don't let this happen to you.  To reiterate more explicitly,  Do NOT size the circuit breakers according to the amp load of the devices hooked to them.
 
Tracy

    ----- Original Message -----
    *From:* David Staten <mailto:Dastaten@earthlink.net>
    *To:* Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
    *Sent:* Monday, October 16, 2006 5:37 AM
    *Subject:* [FlyRotary] What size CB or fuses.. EC 2 items..

    After reviewing the electronic copy of the EC-2 manual I am at a loss
    for an explicit answer.

    What size fuse or CB is appropriate for the injectors.. and for the
    coils (using LS-1 coils and I'm presuming that injectors are
    "Standardized" to either low impedence or high impedance).. I already
    have the resistors for my low impedance coils.

    I intend to run one pair of injector power wires through one CB
    and the
    other pair through another CB just for grins/giggles and I am
    contemplating doing the same with coils as well...(trailing and
    leading
    power leads)..So.. I am actually asking what size CB for 2 coils
    and for
    2 injectors, respectively.. The manual simply says everything in
    Tracy's
    plane (FP, coils, injectors) goes through one big 40 amp breaker...

    Dave

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