Return-Path: Received: from fed1rmmtao06.cox.net ([68.230.241.33] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP id 618966 for flyrotary@lancaironline.net; Mon, 24 Jan 2005 00:54:58 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.33; envelope-from=dale.r@cox.net Received: from smtp.west.cox.net ([172.18.180.52]) by fed1rmmtao06.cox.net (InterMail vM.6.01.04.00 201-2131-117-20041022) with SMTP id <20050124055425.QXDK17071.fed1rmmtao06.cox.net@smtp.west.cox.net> for ; Mon, 24 Jan 2005 00:54:25 -0500 X-Mailer: Openwave WebEngine, version 2.8.15 (webedge20-101-1103-20040528) From: Dale Rogers To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Wire/fuse sizes in aircraft Date: Mon, 24 Jan 2005 0:54:28 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Message-Id: <20050124055425.QXDK17071.fed1rmmtao06.cox.net@smtp.west.cox.net> About page 30 http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/99c827db9baac81b86256b4500596c4e/$FILE/Chapter%2011.pdf Dale R. > > From: "Marc Wiese" > Date: 2005/01/23 Sun PM 07:06:54 EST > To: "Rotary motors in aircraft" > Subject: [FlyRotary] Wire/fuse sizes in aircraft > > You guys really need to get the FAA's AC 43.13 1A and B (latest ones are > greatly revised!). It is the bible for aircraft repair; and in it in the > electrical section it gives wire sizes depending on load, voltage and > length, and from that you can figure the fusing you need. It is required > reading for anybody who wants to get a repairman's certificate or has > gotten an A/P license. If your intend to build an aircraft, you need > these books. Also check those switches-don't use AC switches. Use > switches rated for DC. Test will be at 8 am tomorrow. > Marc Wiese > > -----Original Message----- > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On > Behalf Of Dale Rogers > Sent: Saturday, January 22, 2005 9:06 PM > To: Rotary motors in aircraft > Subject: [FlyRotary] Re: Fuel Pump Load > > Wendell Voto wrote: > > > Okay, I'm conviced, I'll go for 100% over rated current draw. > > > Wendell, > > You are on the verge of being a victim of over-simplification. > I'll try to be as succinct as possible and still cover the > important considerations. > > Rule number 1: The fuse/breaker is there to protect the > wire. If too much current is pushed through the wire, it > will melt. You don't want that to happen. > > Rule number 2: The wire MUST be large enough to handle > all the loads connected to it - plus a "fudge" factor of > about 10 - 30%. Remember: larger wire == more weight, so > you want to keep your wire sizes pretty close to the actual > loads they'll be carrying. Over on one of the canard lists, > someone put up a chart of how much current each wire size > will carry. Probably Aeroelectric has a similar chart. > > Rule number 3: If your fuse is too big for the wire, the > wire will protect the fuse. You don't want that to happen. > > Here's an example of how to pick your wire/fuse combination: > > The maximum output of the alternator is 65 Amps. A #6 wire > will carry about 54A - up to 33 feet - without an excessive > rise in temperature (35*C over ambient). A #4 wire will > carry up to 72A under the same conditions. > > Since your worst-case normal operation only passes 65A - and > is usually a lot less - a 70A breaker should never trip > unless something is seriously awry, yet still trip before > your wire gets too hot from a short. > > Hope this is some help. > Dale R. > COZY MkIV #1254 > > > > >> Homepage: http://www.flyrotary.com/ > >> Archive: http://lancaironline.net/lists/flyrotary/List.html > > > > >> Homepage: http://www.flyrotary.com/ > >> Archive: http://lancaironline.net/lists/flyrotary/List.html >