---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 03/10/22: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:04 AM - Z101b Fusing Question. (Jeffrey Cohen) 2. 12:09 PM - Re: Z101b Fusing Question. (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 07:04:56 AM PST US From: Jeffrey Cohen Subject: AeroElectric-List: Z101b Fusing Question. I am implementing Z101b on my experimental RV7 Aircraft. Why does Z101b shows NO fuse or fusible Link Wire from the FAT WIRE TIE POINT to the ENG BUS ALT FEED RELAY? Same question, why no fuse for the wire from the BATTERY CONTACTOR to the DIODE BRIDGE NTE53016? Any thoughts why Bob did not fuse protect these wires? With a short, put 100A through a 12GA or 14GA wire, and it will get red hot and light something else on fire. Jeff Jcohen@post.com Jeff Cohen Jcohen@post.com 734-323-7421 ________________________________ Message 2 _____________________________________ Time: 12:09:10 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Z101b Fusing Question. At 09:04 AM 3/10/2022, you wrote: > >I am implementing Z101b on my experimental RV7 Aircraft. > >Why does Z101b shows NO fuse or fusible Link Wire from the FAT WIRE >TIE POINT to the ENG BUS ALT FEED RELAY? > >Same question, why no fuse for the wire from the BATTERY CONTACTOR >to the DIODE BRIDGE NTE53016? > >Any thoughts why Bob did not fuse protect these wires? With a short, >put 100A through a 12GA or 14GA wire, and it will get red hot and >light something else on fire. Wires that are part of the distribution system (fat wires) are generally heavy, short and mechanically well protected from severe faults. Many such examples can be found on a variety of aircraft of all sizes. In TC aircraft like a C172, you don't find circuit protection on battery, starter and bus feeders. We DO see protection on battery end of alternator b-leads in deference to the potential for hard fault inside an alternator . . . exceedingly rare these days but the practice persists in both cars and aircraft. As to the hypothetical 100A 'short' . . . study the mechanics of your system installation to deduce how such a short might happen? Consider the extensive bus-bar structures behind the breaker panels of many aircraft . . . breakers fed by fat wires with mechanically and electrically low/zero risk for hard faults. Some of your airplane's components are considered by design and practice to be free of risk for catastrophic failure. Judiciously installed fat-wire feeders are among those components. On the other hand, wires that branch out from bus bars driven by those feeders are at greater risk due to relatively small size, real estate they traverse and appliances they power . . . each appliance feeder gets its own appropriately sized fuse/breaker. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.