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Z101 Fuseable link question

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jcohen@post.com

Joined: 10 Mar 2022
Posts: 17

Posted: Mon Mar 06, 2023 7:19 am Post subject: Z101 Fuseable link question

On reviewing Mudfly's Schematics, and the Z101 Rev b, I have a basic question on the implementation of fusible links for the power feed wire from the main power bus to the bus input (pin 6) on the LR-3 (via the Master Switch).



1. Z101 has 20AWG wire for this line, but the fusible link appears to be 20FLW(#) using 16AWG? Shouldn't this be a 24AWG fusible link to protect a 20AWG wire? Is this a typo or, as I am learning with Z101 and Bob's excellent work, is there a good reason for this? Am I mistaken on what fusible link nomenclature 20FLW(#)-16AWG means? Does the Breaker in-line on this wire affect the FLW selection?



2. Mudfly appears to be using 18AWG for the above wire, but the same fusible link setup. Is this correct?



3. One more question: If protection of the Alternator B line is important but for a very rare event, why bother with ANL devices that need space on a firewall, when fusible links are clearly simpler, lighter, cheaper, and most likely more reliable?



Thank you for your help educating me on this stuff.

_________________
Jeff

Ceengland

Joined: 11 Oct 2020
Posts: 391
Location: MS

Posted: Mon Mar 06, 2023 8:02 am Post subject: Z101 Fuseable link question

On 3/6/2023 9:19 AM, jcohen(at)post.com wrote:

 	  Quote: 	
		   



 On reviewing Mudfly's Schematics, and the Z101 Rev b, I have a basic question on the implementation of fusible links for the power feed wire from the main power bus to the bus input (pin 6) on the LR-3 (via the Master Switch).



 1. Z101 has 20AWG wire for this line, but the fusible link appears to be 20FLW(#) using 16AWG? Shouldn't this be a 24AWG fusible link to protect a 20AWG wire? Is this a typo or, as I am learning with Z101 and Bob's excellent work, is there a good reason for this? Am I mistaken on what fusible link nomenclature 20FLW(#)-16AWG means? Does the Breaker in-line on this wire affect the FLW selection?



 2. Mudfly appears to be using 18AWG for the above wire, but the same fusible link setup. Is this correct?



 3. One more question: If protection of the Alternator B line is important but for a very rare event, why bother with ANL devices that need space on a firewall, when fusible links are clearly simpler, lighter, cheaper, and most likely more reliable?



 Thank you for your help educating me on this stuff.



 --------

I'm not looking at either drawing at the moment, but I'd bet that #1 is 
	


because 24AWG wire is pretty fragile, and relatively uncommon in small 

a/c anyway. Not sure why Bob picked 20/16 in that spot instead of 22/18, 

unless it was to keep some level of commonality with other wires already 

spec'd in the system, or perhaps to minimize voltage drop which might 

affect regulation stability in the regulator.



For #3, I used 12AWG link wire for the link and 8AWG welding cable for 

the B-lead, on  55A alternators. B-lead length is pretty short on my 

installation; probably around 2 feet for each alternator (alternative 

engine with both alts on the accessory end of the engine). I really like 

using the link wire, to save weight, number of connections, money, etc.



-- 

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_________________
Charlie

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Mar 06, 2023 9:13 am Post subject: Z101 Fuseable link question

At 09:19 AM 3/6/2023, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "jcohen(at)post.com" <jcohen(at)post.com>



 On reviewing Mudfly's Schematics, and the Z101 Rev b, I have a

 basic question on the implementation of fusible links for

 the power feed wire from the main power bus to the bus

 input (pin 6) on the LR-3 (via the Master Switch). 	


    Yes, RevB to Z101 corrected an oversight in

    depiction of the BUS EXTENSION from the main

    bus feeder out to the circuit breaker dictated

    by incorporation of a crowbar ov management

    system.



    The segment from FAT wires out to the breaker

    is a distribution feature that COULD be serviced

    by a 24FWL driving a 20AWG feeder. Fusible

    link wire is not common available in sizes less

    than 20 which dictates a feeder of 16AWG or

    larger. This is a one-of-a-kind situation so

    I wouldn't work too hard to get a hunk of 16AWG

    for that segment. 14 or even 12 would be fine

    to.



    Once past the breaker, the pathway becomes

    an appliance feeder with wire sizes suggested

    by installation requirements for that appliance.



  	  Quote: 	
		  1. Z101 has 20AWG wire for this line, but the fusible link appears to be 20FLW(#) using 16AWG? 	


    No, that's 20FWL fusible link wire . . .



  https://tinyurl.com/2p9eyv46



    spliced onto a 16AWG (or larger) extension

    out to the breaker. That dot with an X thru

    it is a splice.



  	  Quote: 	
		  Shouldn't this be a 24AWG fusible link to protect a 20AWG wire? Is this a typo or, as I am learning with Z101 and Bob's excellent work, is there a good reason for this? Am I mistaken on what fusible link nomenclature 20FLW(#)-16AWG means? Does the Breaker in-line on this wire affect the FLW selection? 	


    Link selection in this case is driven by

    product availability. Now, you COULD build

    your own 24FWL



  http://aeroelectric.com/articles/fuselink/fuselink.html



    . . . acquiring he fiberglas/silicone sleeving

    is probably more effort than off-the-shelf

    fusible link wire.

    

  	  Quote: 	
		  3. One more question: If protection of the Alternator B line is important

 but for a very rare event, why bother with ANL devices that need space

 on a firewall, when fusible links are clearly simpler, lighter, cheaper,

 and most likely more reliable? 	


   Very perceptive. But of course. The car guys have

   been doing this for decades. My KIA has a cluster

   of circuit protective devices right at the battery(+)

   terminal. They look like mini ANL current limiters.

   The wiring diagram calls the 'fusible links'.



   The fact that these could not get any closer to

   the battery terminal should suggest something

   about battery energy hazards in a munch-up.

   Back in our EMT days, one of the FIRST things

   the jaws-of-life guys did on arrival at the

   scene was cut the battery wires . . . assuming

   they could be reached.



 

  	  Quote: 	
		  Thank you for your help educating me on this stuff. 	


   That's what we're here for my friend.



 

   Bob . . .



                    //// 

                   (o o) 

    ===========o00o=(_)=o00o========= 

    < Go ahead, make my day . . .   > 

    < show me where I'm wrong.      > 

    =================================

  

    In the interest of creative evolution

    of the-best-we-know-how-to-do based

    on physics and good practice.

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Mar 06, 2023 9:19 am Post subject: Z101 Fuseable link question

 	  Quote: 	
		  I'm not looking at either drawing at the moment, but I'd bet that #1 is because 24AWG wire is pretty fragile, and relatively uncommon in small a/c anyway. Not sure why Bob picked 20/16 in that spot instead of 22/18, unless it was to keep some level of commonality with other wires already spec'd in the system, or perhaps to minimize voltage drop which might affect regulation stability in the regulator. 	


    20AWG linkwire is the the smallest off-the-shelf

    product I've located thus far. If anyone spots

    something smaller, please give the List a 

    heads-up.



    But it's not a really pressing issue. The 20/16 

    FAT wire extension satisfies crash safety design

    goals . . . the fact that it's a bit 'big' for

    a 5A feeder is no big deal. If that were a 2 AMP

    breaker protecting some device on the airframe,

    the 20/16 extension would still be just fine.



  	  Quote: 	
		  I really like using the link wire, to save weight, number

 of connections, money, etc. 	


    Agreed . . . I'd rather install a fist full

    of butt-splices than one ANL mounting block!



 

   Bob . . .



                    //// 

                   (o o) 

    ===========o00o=(_)=o00o========= 

    < Go ahead, make my day . . .   > 

    < show me where I'm wrong.      > 

    =================================

  

    In the interest of creative evolution

    of the-best-we-know-how-to-do based

    on physics and good practice.

jcohen@post.com

Joined: 10 Mar 2022
Posts: 17

Posted: Mon Mar 06, 2023 12:18 pm Post subject: Re: Z101 Fuseable link question

 	  Quote: 	
		  20AWG linkwire is the the smallest off-the-shelf

product I've located thus far. If anyone spots

something smaller, please give the List a

heads-up. 	




well, if you have $9, this B&C Specialty Products kit works. 



https://bandc.com/product/fusible-link-kit-24-20-awg/



maybe cheaper than trying to buy 6" of Silicone covered fiberglas sleeving on your own.

_________________
Jeff

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Mar 06, 2023 2:46 pm Post subject: Z101 Fuseable link question

At 02:18 PM 3/6/2023, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "jcohen(at)post.com" <jcohen(at)post.com>



 

 > 20AWG linkwire is the the smallest off-the-shelf

 > product I've located thus far. If anyone spots

 > something smaller, please give the List a

 > heads-up.



 

 well, if you have $9, this B&C Specialty Products kit works. 



  https://bandc.com/product/fusible-link-kit-24-20-awg/ 	


   Yep, that works too. I used to sell that

   kit wwaaaaayyyy back when . . .



 

 

   Bob . . .



                    //// 

                   (o o) 

    ===========o00o=(_)=o00o========= 

    < Go ahead, make my day . . .   > 

    < show me where I'm wrong.      > 

    =================================

  

    In the interest of creative evolution

    of the-best-we-know-how-to-do based

    on physics and good practice.

Ceengland

Joined: 11 Oct 2020
Posts: 391
Location: MS

Posted: Wed Mar 08, 2023 5:57 am Post subject: Z101 Fuseable link question

On 3/6/2023 2:18 PM, jcohen(at)post.com (jcohen(at)post.com)       wrote:

     

      	  Quote: 	
		          	  Quote: 	
		  --> AeroElectric-List message posted by: "jcohen(at)post.com" (jcohen(at)post.com) <jcohen(at)post.com> (jcohen(at)post.com)

          	  Quote: 	
		  20AWG linkwire is the the smallest off-the-shelf

product I've located thus far. If anyone spots

something smaller, please give the List a

heads-up.

	
       well, if you have $9, this B&C Specialty Products kit works. 



https://bandc.com/product/fusible-link-kit-24-20-awg/



maybe cheaper than trying to buy 6" of Silicone covered fiberglas sleeving on your own.



--------

Jeff

	
     	
     I tried out a 'catastrophic fault test' on some 22AWG milspec wire     inside a short piece of silicone tubing, and the wire was vaporized     but the silicone tubing completely contained the event. (It did let     the wisp of smoke out, of course.)

     

     Wire is going to be on hand, and silicone tubing could probably be     sourced locally, or certainly from the usual online suspects. A few     dollars and you'd have enough to makesmall gauge link shields for the rest of     your flying career. 

     

     Charlie

     

   

  



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_________________
Charlie

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Mar 08, 2023 4:04 pm Post subject: Z101 Fuseable link question

 	  Quote: 	
		  I tried out a 'catastrophic fault test' on some 22AWG milspec wire inside a short piece of silicone tubing, and the wire was vaporized but the silicone tubing completely contained the event. (It did let the wisp of smoke out, of course.)



 Wire is going to be on hand, and silicone tubing could probably be sourced locally, or certainly from the usual online suspects. A few dollars and you'd have enough to makesmall gauge link shields for the rest of your flying career. 



 Charlie 	


   Good show. Got any pictures?  I can

   append the experiment and your results

   on the DIY fusible link comic book.



 

   Bob . . .



                    //// 

                   (o o) 

    ===========o00o=(_)=o00o========= 

    < Go ahead, make my day . . .   > 

    < show me where I'm wrong.      > 

    =================================

  

    In the interest of creative evolution

    of the-best-we-know-how-to-do based

    on physics and good practice.

Ceengland

Joined: 11 Oct 2020
Posts: 391
Location: MS

Posted: Wed Mar 08, 2023 6:18 pm Post subject: Z101 Fuseable link question

On 3/8/2023 6:04 PM, Robert L.       Nuckolls, III wrote:

     

      	  Quote: 	
		                 	  Quote: 	
		  I           tried out a           'catastrophic fault test' on some 22AWG milspec wire inside a           short piece           of silicone tubing, and the wire was vaporized but the           silicone tubing           completely contained the event. (It did let the wisp of smoke           out, of           course.)

           

           Wire is going to be on hand, and silicone tubing could           probably be           sourced locally, or certainly from the usual online suspects.           A few           dollars and you'd have enough to makesmall gauge link shields           for the           rest of your flying career. 

           

           Charlie 	
       

         Good show. Got any pictures?  I can

         append the experiment and your results

         on the DIY fusible link comic book.

       

                

             Bob . . .

                	
     Just the post-test, disassembled  one I attached to       the message, and one showing the test link, pre and post test. I'm       sending all three direct to your email address. The tubing was       ordered from probably either Amazon or ebay. As I said, it's *not*       clear vinyl; it's silicone. I'd be a little less confident in       vinyl. 

       

       Charlie

        Virus-free.www.avast.com[url=#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2] [/url]

_________________
Charlie

jcohen@post.com

Joined: 10 Mar 2022
Posts: 17

Posted: Thu Mar 09, 2023 6:58 am Post subject: Re: Z101 Fuseable link question

Charlie, great thanks for performing that test! Really helpful for me to understand what to expect.

_________________
Jeff

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