X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 30 [X] Return-Path: Received: from fed1rmmtao104.cox.net ([68.230.241.42] verified) by logan.com (CommuniGate Pro SMTP 5.1.6) with ESMTP id 1851218 for flyrotary@lancaironline.net; Tue, 20 Feb 2007 10:47:24 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.42; envelope-from=alventures@cox.net Received: from fed1rmimpo01.cox.net ([70.169.32.71]) by fed1rmmtao104.cox.net (InterMail vM.7.05.02.00 201-2174-114-20060621) with ESMTP id <20070220154631.TSHS27628.fed1rmmtao104.cox.net@fed1rmimpo01.cox.net> for ; Tue, 20 Feb 2007 10:46:31 -0500 Received: from BigAl ([72.192.132.90]) by fed1rmimpo01.cox.net with bizsmtp id RrmX1W0091xAn3c0000000; Tue, 20 Feb 2007 10:46:31 -0500 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: CBs and fuses Date: Tue, 20 Feb 2007 07:46:33 -0800 Message-ID: <000001c75506$4c06d770$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C754C3.3DE39770" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C754C3.3DE39770 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Subject: [FlyRotary] Re: CBs and fuses Regarding protecting wires instead of loads, when dealing with a $10,000 radio, or a $7,000 EFIS I'm much more concerned with the load than the wire. Call me crazy. John =20 I think you'll find that the radio and EFIS have protection built in (internal fuse, fusible link, etc); or if the radio is causing the fuse = to blow, it is toast already, or perhaps the load can tolerate short-term current that you wouldn't want your wire to carry when it shorts to = ground or another wire. The over heated wire starts a fire and burns up your plane.=20 =20 Whatever the reason; to quote Bob Nuckols, "Fuses and Circuit breakers = are included to in the electrical system to accomplish only one thing: keep = the wiring from creating a fire hazard in the event that the wire becomes overloaded." The FAA publication EA 43-13 says "Protect the wire with = the circuit breaker or fuse located as close as possible to the electrical = power source"; and "The circuit breaker or fuse should open the circuit before = the wire emits smoke" (Duh!). It also includes the words "In order to = obtain the maximum utilization of the connected equipment . . " =20 Clearly the two issues are tied together, the wire sized for "maximum utilization of the equipment" and the circuit protection protecting the = wire (and the airplane) in the event of a short. =20 FWIW, =20 Al =20 --- Al Gietzen wrote: =20 > John;=20 >=20 > Joe gave you good info on loads. I am using the LS1 > coils, and I did have a > 15A fuse blow on one set of (3) coils. It > apparently happened on startup (I > don't recall doing anything behind the panel that > may have caused it), and > apparently under the right conditions, a high draw > can occur when things are > turned on. The engine, of course, still started and > ran on the other set of > coils, but I could tell something wasn't entirely > cricket. >=20 > I have looked for slow-blow blade-type fuses, but > have not found them. >=20 > Just as a reminder, the estimated loads are useful > in sizing wires, but > circuit protection is selected to protect the wire; > not the load. >=20 > Al >=20 =20 =20 -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ ------=_NextPart_000_0001_01C754C3.3DE39770 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Subject: [FlyRotary] Re: CBs and fuses

Regarding protecting

wires instead of loads, when dealing with a $10,000

radio, or a $7,000 EFIS I'm much more concerned with

the load than the wire. Call me crazy.

       &nbs= p;            = ;     John

 

I think you’ll find that the radio and EFIS = have protection built in (internal fuse, fusible link, etc); or if the radio = is causing the fuse to blow, it is toast already, or perhaps the load can = tolerate short-term current that you wouldn’t want your wire to carry when = it shorts to ground or another wire.  The over heated wire starts a = fire and burns up your plane.

 

Whatever the reason; to quote Bob Nuckols, = “Fuses and Circuit breakers are included to in the electrical system to = accomplish only one thing: keep the wiring from creating a fire hazard in the event = that the wire becomes overloaded.”  The FAA publication EA 43-13 = says “Protect the wire with the circuit breaker or fuse located as close as possible = to the electrical power source”; and “The circuit breaker or fuse = should open the circuit before the wire emits smoke” (Duh!).  It = also includes the words “In order to obtain the maximum utilization of = the connected equipment . . “

 

Clearly the two issues are tied together, the wire = sized for “maximum utilization of the equipment” and the circuit protection protecting the wire (and the airplane) in the event of a = short.

 

FWIW,

 

Al

 

--- Al Gietzen <ALVentures@cox.net> wrote:

 

> John;

>

> Joe gave you good info on loads.  I am using the = LS1

> coils, and I did have a

> 15A fuse blow on one set of (3) coils.  It

> apparently happened on startup (I

> don't recall doing anything behind the panel that

> may have caused it), and

> apparently under the right conditions, a high draw

> can occur when things are

> turned on.  The engine, of course, still started = and

> ran on the other set of

> coils, but I could tell something wasn't entirely

> cricket.

>

> I have looked for slow-blow blade-type fuses, but

> have not found them.

>

> Just as a reminder, the estimated loads are useful

> in sizing wires, but

> circuit protection is selected to protect the wire;

> not the load.

>

> Al

>

 

 

--

Homepage:  http://www.flyrotary.com/

Archive and UnSub:   = http://mail.lancaironline.net/lists/flyrotary/

------=_NextPart_000_0001_01C754C3.3DE39770--