X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 06 Nov 2007 16:28:45 -0500 Message-ID: X-Original-Return-Path: Received: from vms044pub.verizon.net ([206.46.252.44] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2457717 for lml@lancaironline.net; Tue, 06 Nov 2007 01:59:13 -0500 Received-SPF: pass receiver=logan.com; client-ip=206.46.252.44; envelope-from=tom.gourley@verizon.net Received: from jacky0da39824a ([71.111.155.229]) by vms044.mailsrvcs.net (Sun Java System Messaging Server 6.2-6.01 (built Apr 3 2006)) with ESMTPA id <0JR200GQYOPBQIB1@vms044.mailsrvcs.net> for lml@lancaironline.net; Tue, 06 Nov 2007 00:58:26 -0600 (CST) X-Original-Date: Mon, 05 Nov 2007 22:58:13 -0800 From: "Tom Gourley" Subject: Re: [LML] Re: Design for Circuit Breakers & Fuses? X-Original-To: "Lancair Mailing List" Reply-to: "Tom Gourley" X-Original-Message-id: <003101c82042$66fc72d0$650610ac@jacky0da39824a> MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 X-Mailer: Microsoft Outlook Express 6.00.2900.3138 Content-type: multipart/alternative; boundary="----=_NextPart_000_002E_01C81FFF.583E2B50" X-Priority: 3 X-MSMail-priority: Normal References: This is a multi-part message in MIME format. ------=_NextPart_000_002E_01C81FFF.583E2B50 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable It's interesting to see that a lot of builders prefer a mix of breakers = and fuses. I like the flexibility and observability of the Klixon 7277 = breakers. (BTW, Aerocraft Parts still has very good prices on these = compared to other suppliers.) The flexibility of being able to quickly = and selectively control power to various components is very convenient = when initially bringing up and testing a new panel as well as a newly = wired airframe. It also provides the most options if there is an = in-flight problem. The observability part means if something quits = working you can visually scan the breakers and easily see if one has = tripped. That's harder to do with fuses, although it wouldn't be all = that hard to set up annuciators that would let you know if a fuse has = blown; and even tell you which fuse. =20 On the other hand, as some folks have pointed out, there's not a lot of = room on some panels, the Legacy in particular. Putting some devices on = fuses to free up panel space is not a bad idea, as long as they are = things that you'd be ok with simply leaving off until after landing. If = the proper fuse/circuit breakers and wire gauges are used then a blown = fuse or tripped breaker most times indicates a problem that isn't going = to go away by resetting the circuit. It may go away for a while, but it = will very likely be back. As an engineer I once worked with liked to = say, "Problems that go away on their own, come back on their own." I guess the bottom line is each builder is free to decide what works = best for their airplane, which is one of the fun things about being = experimental. Tom Gourley ------=_NextPart_000_002E_01C81FFF.583E2B50 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
It's interesting to see that a lot of = builders=20 prefer a mix of breakers and fuses.  I like the flexibility and=20 observability of the Klixon 7277 breakers.  (BTW, Aerocraft Parts = still has=20 very good prices on these compared to other suppliers.)  The = flexibility of=20 being able to quickly and selectively control power to various = components=20 is very convenient when initially bringing up and testing a new panel as = well as=20 a newly wired airframe.  It also provides the most options if there = is an=20 in-flight problem.  The observability part means if something quits = working=20 you can visually scan the breakers and easily see if one has = tripped. =20 That's harder to do with fuses, although it wouldn't be all that = hard to=20 set up annuciators that would let you know if a fuse has blown; and even = tell=20 you which fuse. 
 
On the other hand, as some folks have = pointed out,=20 there's not a lot of room on some panels, the Legacy in = particular. =20 Putting some devices on fuses to free up panel space is = not a bad=20 idea, as long as they are things that you'd be ok with simply leaving = off until=20 after landing.  If the proper fuse/circuit breakers and wire gauges = are=20 used then a blown fuse or tripped breaker most times indicates = a=20 problem that isn't going to go away by resetting the circuit.  It = may go=20 away for a while, but it will very likely be back. As an engineer I once = worked=20 with liked to say, "Problems that go away on their own, come = back on their=20 own."
 
I guess the bottom line is each builder = is free to=20 decide what works best for their airplane, which is one of the fun = things about=20 being experimental.
 
Tom Gourley
 
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