---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 12/26/16: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:33 AM - A couple of questions about Fuses (Carlos Trigo) 2. 06:17 AM - Re: A couple of questions about Fuses (Art Zemon) 3. 06:29 AM - Re: A couple of questions about Fuses (Charlie England) 4. 06:37 AM - Re: A couple of questions about Fuses (user9253) 5. 08:09 AM - Re: Re: A couple of questions about Fuses (C&K) 6. 07:06 PM - Securing Split PVC Conduit (Art Zemon) ________________________________ Message 1 _____________________________________ Time: 03:33:05 AM PST US From: "Carlos Trigo" Subject: AeroElectric-List: A couple of questions about Fuses Good morning 'letric Bob and all 'letric experts. I hope you had a Merry Christmas! In my fused power busses I decided to use LED blade fuses, those whose LED gets illuminated when the fuse trips. It happens that I have a couple of circuits which require a 1A fuse, but there are no 1A LED blade fuses. Therefore, in these circuits, either I use a normal (non-illuminated) 1A fuse, or I go for a 2A illuminated fuse. What happens if I decide for the latter? Do I get less protection? Is that particular device more prone to be fried? Now, for the second question, in a broader perspective: I have heard dozens of times that a fuse (or other protection device) is there to protect the wire and not the device at its end. However, the size (in A) of the fuse is determined by the device in use (you read in the installation manuals that "to protect this device, you should use a 3A fuse or circuit breaker"). I know that this depends on the power (W) that is used by the device when working, and that both the wire and the fuse must be sized accordingly. I also know that if we use a thinner wire, it will get very hot and eventually melt. But what about using an higher A or a lesser A fuse? What are the physics involved? Thanks Carlos ________________________________ Message 2 _____________________________________ Time: 06:17:13 AM PST US From: Art Zemon Subject: Re: AeroElectric-List: A couple of questions about Fuses Hi Carlos, Take a look at chapter 10, circuit protection, in *The AeroElectric Connection*. And here are a few articles: http://www.aeroelectric.com/articles.html#Circuit Protection In building my plane, I am following the advice to size the fuse for the wire, except in a couple of cases where I only need a couple of amps and did not feel like installing tiny wire. In those cases, I went ahead and used an undersized fuse, even though the wire is capable of carrying more current. Cheers, -- Art Z. On Mon, Dec 26, 2016 at 5:31 AM, Carlos Trigo wrote : > Good morning =98letric Bob and all =98letric experts. > > I hope you had a Merry Christmas! > > > In my fused power busses I decided to use LED blade fuses, those whose LE D > gets illuminated when the fuse trips. > > It happens that I have a couple of circuits which require a 1A fuse, but > there are no 1A LED blade fuses. Therefore, in these circuits, either I u se > a normal (non-illuminated) 1A fuse, or I go for a 2A illuminated fuse. > > What happens if I decide for the latter? Do I get less protection? Is tha t > particular device more prone to be fried? > > > Now, for the second question, in a broader perspective: I have heard > dozens of times that a fuse (or other protection device) is there to > protect the wire and not the device at its end. > > However, the size (in A) of the fuse is determined by the device in use > (you read in the installation manuals that =9Cto protect this devic e, you > should use a 3A fuse or circuit breaker=9D). > > I know that this depends on the power (W) that is used by the device when > working, and that both the wire and the fuse must be sized accordingly. I > also know that if we use a thinner wire, it will get very hot and > eventually melt. > > But what about using an higher A or a lesser A fuse? What are the physics > involved? > > > Thanks > > Carlos > -- https://CheerfulCurmudgeon.com/ *"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel* ________________________________ Message 3 _____________________________________ Time: 06:29:19 AM PST US Subject: Re: AeroElectric-List: A couple of questions about Fuses From: Charlie England Charlie On Dec 26, 2016, 6:40 AM, at 6:40 AM, Carlos Trigo wrote: >Good morning 'letric Bob and all 'letric experts. > >I hope you had a Merry Christmas! > > > >In my fused power busses I decided to use LED blade fuses, those whose >LED >gets illuminated when the fuse trips. > >It happens that I have a couple of circuits which require a 1A fuse, >but >there are no 1A LED blade fuses. Therefore, in these circuits, either I >use >a normal (non-illuminated) 1A fuse, or I go for a 2A illuminated fuse. > >What happens if I decide for the latter? Do I get less protection? Is >that >particular device more prone to be fried? > > > >Now, for the second question, in a broader perspective: I have heard >dozens >of times that a fuse (or other protection device) is there to protect >the >wire and not the device at its end. > >However, the size (in A) of the fuse is determined by the device in use >(you >read in the installation manuals that "to protect this device, you >should >use a 3A fuse or circuit breaker"). > >I know that this depends on the power (W) that is used by the device >when >working, and that both the wire and the fuse must be sized accordingly. >I >also know that if we use a thinner wire, it will get very hot and >eventually >melt. > >But what about using an higher A or a lesser A fuse? What are the >physics >involved? > > > >Thanks > >Carlos ________________________________ Message 4 _____________________________________ Time: 06:37:26 AM PST US Subject: AeroElectric-List: Re: A couple of questions about Fuses From: "user9253" Fuses that glow when blown depend on the load to complete the circuit. If the load circuit happens to open up as a result of the malfunction, the fuse will not glow. While the above scenario is possible, it is not likely. If some electrical device does not work, check the glow-type fuse with a meter to be sure that it is not blown. Yes, the larger the fuse, the less protection there is. By protection, I am talking about protection against smoke in the cockpit. As far as protection for the electrical device, it doesn't matter if the fuse is 1 amp or 2 amps or 5 amps. If the device shorts out, it will be fried regardless of the fuse size. A lager fuse size will not make any electrical device more prone to fail. Many devices have internal fuses to protect against internal short circuits. 22 AWG wire can be protected by a 3 amp fuse. But if a device only requires one half amp, then a 1 amp fuse will offer more protection against smoke if the device ever shorts out. Bottom line is, you can use either a 1 amp or 2 amp fuse. A 1 amp will give more peace of mind. A 2 amp will work too. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=464402#464402 ________________________________ Message 5 _____________________________________ Time: 08:09:13 AM PST US Subject: Re: AeroElectric-List: Re: A couple of questions about Fuses From: C&K I would add that I have seen cases where the recommended small fuse popped after many years. Replacing the fuse with a handy slightly larger fuse also popped but this time it was accompanied by smoke from the transponder. Neither fuse put the wire at any risk and likely the smoke would have stopped by itself but I prefer to follow the manufacturers fuse recommendation. OTOH I don't worry about going up to the appropriate larger wire protection fuse in cases where it is convenient to put multiple items on the same fuse. Of larger concern to me are some of the very small gage cords that get plugged into 15 amp circuits in houses. Ken On 26/12/2016 9:35 AM, user9253 wrote: > > Fuses that glow when blown depend on the load to complete the circuit. If the load circuit happens to open up as a result of the malfunction, the fuse will not glow. While the above scenario is possible, it is not likely. If some electrical device does not work, check the glow-type fuse with a meter to be sure that it is not blown. > Yes, the larger the fuse, the less protection there is. By protection, I am talking about protection against smoke in the cockpit. As far as protection for the electrical device, it doesn't matter if the fuse is 1 amp or 2 amps or 5 amps. If the device shorts out, it will be fried regardless of the fuse size. A lager fuse size will not make any electrical device more prone to fail. Many devices have internal fuses to protect against internal short circuits. > 22 AWG wire can be protected by a 3 amp fuse. But if a device only requires one half amp, then a 1 amp fuse will offer more protection against smoke if the device ever shorts out. > Bottom line is, you can use either a 1 amp or 2 amp fuse. A 1 amp will give more peace of mind. A 2 amp will work too. > > -------- > Joe Gores > > ________________________________ Message 6 _____________________________________ Time: 07:06:51 PM PST US From: Art Zemon Subject: AeroElectric-List: Securing Split PVC Conduit Folks, I am using some split PVC conduit in my plane and two of the runs are pretty close to vertical, about 4 feet long. Sitting in my garage, with the wires not yet secured at the bottom, the conduit keeps trying to slide downward in the 2 inch square channels through which it runs. I think that I ought to secure it somehow and wonder if you have any ideas that will keep it in place. Maybe I can wrap a thin cable tie around it and get it to slip into a groove? Or maybe wrap it with silicone self-sealing tape and the put an AN742 clamp around it? Thanks, -- Art Z. -- https://CheerfulCurmudgeon.com/ *"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel* ------------------------------------------------------------------------------------- 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.