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		Area-51
 
 
  Joined: 03 May 2021 Posts: 439
 
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				 Posted: Tue Apr 25, 2023 2:48 am    Post subject: Wiring Looms | 
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				Have over 40yrs experience in automotive and now swapped to aviation; what an absolute joy!!
 
 Regarding wiring looms.. what spec wire are people using in aircraft looms, and what is being used as the outer protective sheathing? Is it a specific shrink wrap fire retardant material?
 
 Thanks in advance.
 
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		johnbright
 
  
  Joined: 14 Dec 2011 Posts: 166 Location: Newport News, VA
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				 Posted: Tue Apr 25, 2023 3:31 am    Post subject: Re: Wiring Looms | 
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				My wire notes are in the footnote of this document: https://docs.google.com/document/d/1s0xBEMmMzSyXW6S1vXLYCvqcWpzj2znVb23ZVKWSLfI/edit?usp=drivesdk
 
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  _________________ John Bright, RV-6A, at FWF, O-360
 
Z-101 single batt dual alt SDS EM-5-F.
 
john_s_bright@yahoo.com, Newport News, Va
 
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		Area-51
 
 
  Joined: 03 May 2021 Posts: 439
 
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				 Posted: Tue Apr 25, 2023 2:28 pm    Post subject: Re: Wiring Looms | 
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				Thanks John.. will look for a related spec chart based on your info; found it all a bit difficult to comprehend regarding number codes there... maybe they are related to a specific aircraft kit product
 
 I get the AWG and Tefzel sude of things.. Are there any known Tefzel shrink wrap sheathing products out there for finishing off custom wiring?
 
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		Eric Page
 
 
  Joined: 15 Feb 2017 Posts: 260
 
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		chaskuss(at)yahoo.com Guest
 
 
 
 
 
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				 Posted: Tue Apr 25, 2023 8:02 pm    Post subject: Wiring Looms | 
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				Mil Spec 22759/16   aka Tefzel wire. The wire you find on oxygen sensors is the same. The copper wire is tinned to prevent corrosion. The Tefzel insulation withstands high heat [150 C] and  abrasion. Under the cowl you can use Mil Spec 22759/11, which has silver, rather than solder coating the copper strands. The insulation is Teflon, rather than Tefzel. This wire withstands higher heat [200 C] than 22759/16. The Teflon insulation is softer, so it can be bent into tighter radii. Many avionics shops will use the /11 wire behind the instrument panel, to allow tighter loops in the harness. One caveat with the /11 wire, don't secure it to tightly or use Nylon wire ties, as this can saw through the soft Teflon insulation over time. FYI, I have found it easier to get the /11 wire in colors. 
 
 Charlie
 
                   
                                                                     On Tuesday, April 25, 2023 at 06:57:13 AM EDT, Area-51 <goldsteinindustrial(at)gmail.com> wrote:                 
                  
 
                  
 
                  --> AeroElectric-List message posted by: "Area-51" <goldsteinindustrial(at)gmail.com (goldsteinindustrial(at)gmail.com)>
 
 Have over 40yrs experience in automotive and now swapped to aviation; what an absolute joy!!
 
 Regarding wiring looms.. what spec wire are people using in aircraft looms, and what is being used as the outer protective sheathing? Is it a specific shrink wrap fire retardant material?
 
 Thanks in advance.
 
 Read this topic online here:
 
 http://forums.matronics.com/viewtopic.php?p=510698#510698
 
 _-= the many List utilities such as List Un/Subscription,
 
 http://www.matronics.com/Navigator?AeroElectric-List
 
 http://forums.matronics.com
 
 http://wiki.sp;                     &=   -->
 
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		nuckolls.bob(at)aeroelect Guest
 
 
 
 
 
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				 Posted: Wed Apr 26, 2023 9:10 am    Post subject: Wiring Looms | 
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				At 05:48 AM 4/25/2023, you wrote:
   	  | Quote: | 	 		  --> AeroElectric-List message posted by: "Area-51" <goldsteinindustrial(at)gmail.com>
 
  Have over 40yrs experience in automotive and now swapped to aviation; what an absolute joy!!
 
  Regarding wiring looms.. what spec wire are people using in aircraft looms, and what is being used as the outer protective sheathing? Is it a specific shrink wrap fire retardant material?
 
  Thanks in advance. | 	  
     Designers of TC aircraft go out of their
     way to avoid a necessity for mechanically
     shielding wire bundles.  When external
     covers are found on the drawings, there's
     a special risk for mechanical damage to
     the bundle . . . wheel wells, exposure to
     foot traffic, etc.
 
     There are lots of things in airplanes
     that would suffer operational compromise
     if they came into antagonistic contact
     with foreign bodies. Bus bars, control cables . . .
     and yeah, wire bundles.
 
     First rule of thumb is to conduct the failure
     modes effects analysis to identify risk and
     then eliminate it. If not possible/practical,
     then add 'shielding'.  Shielding is rarely
     found to be useful.
 
  
  
    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
 
 
 
 
 
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				 Posted: Wed Apr 26, 2023 9:28 am    Post subject: Wiring Looms | 
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				 	  | Quote: | 	 		  | Under the cowl you can use Mil Spec 22759/11, which has silver, rather than solder coating the copper strands. The insulation is Teflon, rather than Tefzel. This wire withstands higher heat [200 C] than 22759/16. The Teflon insulation is softer, so it can be bent into tighter radii. Many avionics shops will use the /11 wire behind the instrument panel, to allow tighter loops in the harness. One caveat with the /11 wire, don't secure it to tightly or use Nylon wire ties, as this can saw through the soft Teflon insulation over time. FYI, I have found it easier to get the /11 wire in colors.  | 	   
  
    Teflon over silver plated wire is not
    recommended for general airframe wiring
    or appliance fabrication. I don't think
    our wire bundle shops even had Teflon
    in inventory . . .
 
    Had a conversation about Teflon with
    with Greg Richter of BlueMountain fame
    starting on page 38 of this document:
 
   https://tinyurl.com/2tbearkn
 
   
 
  
    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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		Area-51
 
 
  Joined: 03 May 2021 Posts: 439
 
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				 Posted: Thu May 04, 2023 12:51 am    Post subject: Re: Wiring Looms | 
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				Thanks guys for all the input there...
 
 The Tefzel i'm aware of, and its my preference... but what options are people using to wrap the bundle in? Are there any fire retardant shrink wrap products available? 
 
 I would not feel convinced with silver coated traces; its a great conductor but brittle over time.
 
 I thought shielding is required to mitigate RF generated interference to avionics?? And i'm aware of the purpose for twisted pairs, and how they affect CANBUS signals.
 
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		nuckolls.bob(at)aeroelect Guest
 
 
 
 
 
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				 Posted: Thu May 04, 2023 7:46 am    Post subject: Wiring Looms | 
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				At 03:51 AM 5/4/2023, you wrote:
   	  | Quote: | 	 		  --> AeroElectric-List message posted by: "Area-51" <goldsteinindustrial(at)gmail.com>
 
  Thanks guys for all the input there...I would not feel convinced with silver coated traces; its a great conductor but brittle over time. | 	  
     The use of silver plating on Teflon insulated
     wires is necessary because of high extrusion
     temperatures for Teflon . . . not for improved
     conductivity. Tinned conductors are not compatible
     with Teflon insulation.
 
   	  | Quote: | 	 		  | I thought shielding is required to mitigate RF generated interference to avionics?? | 	  
     Please review the chapter in the 'Connection on
     electro-magnetic compatibility practice. Ideally,
     the well crafted installation of qualified
     appliances in airplanes (or any other vehicle)
     do not require shielding of any kind. You
     will be hard pressed to find a shielded wire
     in any system in your car . . . or TC aircraft.
     They are rare.
 
     I can't remember the last time I found it
     necessary to shield any wire.
 
  
  
    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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		jluckey(at)pacbell.net Guest
 
 
 
 
 
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				 Posted: Thu May 04, 2023 8:01 am    Post subject: Wiring Looms | 
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				I will throw in one asterisk *  ...
 Many Avionics manufacturers recommend the use of shielded cables for their data bus wiring.
  OK, 2 asterisks...
 Also, it is fairly common practice to shield low-level audio wires.
 
 
 -Jeff
                   
                                                                     On Thursday, May 4, 2023 at 08:51:49 AM PDT, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com> wrote:                 
                  
 
                  
 
                    At 03:51 AM 5/4/2023, you wrote:
   	  | Quote: | 	 		  --> AeroElectric-List message posted by: "Area-51" <goldsteinindustrial(at)gmail.com>
 
  Thanks guys for all the input there...I would not feel convinced with silver coated traces; its a great conductor but brittle over time. | 	  
     The use of silver plating on Teflon insulated
     wires is necessary because of high extrusion
     temperatures for Teflon . . . not for improved
     conductivity. Tinned conductors are not compatible
     with Teflon insulation.
 
   	  | Quote: | 	 		  | I thought shielding is required to mitigate RF generated interference to avionics?? | 	  
     Please review the chapter in the 'Connection on
     electro-magnetic compatibility practice. Ideally,
     the well crafted installation of qualified
     appliances in airplanes (or any other vehicle)
     do not require shielding of any kind. You
     will be hard pressed to find a shielded wire
     in any system in your car . . . or TC aircraft.
     They are rare.
 
     I can't remember the last time I found it
     necessary to shield any wire.
 
  
  
     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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		Ceengland
 
 
  Joined: 11 Oct 2020 Posts: 394 Location: MS
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				 Posted: Thu May 04, 2023 8:19 am    Post subject: Wiring Looms | 
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				It is common practice with a/c audio wires, but it rarely does anything helpful. The reason  is that a/c audio is 'low impedance'; around 600 ohms, and is far less susceptible to picking up radiated noise than the wiring in a home stereo, where the low level stuff is ~50k ohms impedance. 
 Similar situation with data. I wonder if the mfgrs of avionics are just hoping that one more layer of 'stuff' may head off a service complaint.
 Charlie
 Audio tech, and service tech, in a couple of past lives
 On Thu, May 4, 2023 at 11:06 AM Jeff Luckey <jluckey(at)pacbell.net (jluckey(at)pacbell.net)> wrote:
 
  	  | Quote: | 	 		  
          I will throw in one asterisk *  ...
 Many Avionics manufacturers recommend the use of shielded cables for their data bus wiring.
  OK, 2 asterisks...
 Also, it is fairly common practice to shield low-level audio wires.
 
 
 -Jeff
                   
                                                                     On Thursday, May 4, 2023 at 08:51:49 AM PDT, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:                 
                  
 
                  
 
                    At 03:51 AM 5/4/2023, you wrote:
   	  | Quote: | 	 		  --> AeroElectric-List message posted by: "Area-51" <goldsteinindustrial(at)gmail.com (goldsteinindustrial(at)gmail.com)>
 
  Thanks guys for all the input there... | 	     
 
  
   	  | Quote: | 	 		  | I would not feel convinced with silver coated traces; its a great conductor but brittle over time. | 	  
     The use of silver plating on Teflon insulated
     wires is necessary because of high extrusion
     temperatures for Teflon . . . not for improved
     conductivity. Tinned conductors are not compatible
     with Teflon insulation.
 
   	  | Quote: | 	 		  | I thought shielding is required to mitigate RF generated interference to avionics?? | 	  
     Please review the chapter in the 'Connection on
     electro-magnetic compatibility practice. Ideally,
     the well crafted installation of qualified
     appliances in airplanes (or any other vehicle)
     do not require shielding of any kind. You
     will be hard pressed to find a shielded wire
     in any system in your car . . . or TC aircraft.
     They are rare.
 
     I can't remember the last time I found it
     necessary to shield any wire.
 
  
  
     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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  _________________ Charlie | 
			 
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		jluckey(at)pacbell.net Guest
 
 
 
 
 
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				 Posted: Thu May 04, 2023 8:43 am    Post subject: Wiring Looms | 
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				Interesting observations.  But from a practical point of view...
 Charlie, that may be the case, but I would not want to be in a situation where something is not working correctly, possibly due to some kind of interference, and having to explain to manufacturer's tech support that I did not comply with their recommended procedures.  It could give them license to say: "Well it's on you, then".
 Same thing goes for customers.  I would have trouble trying to explain to a customer why I didn't comply with the manufacturer's recommendations.
 
 
 -Jeff
                   
                                                                     On Thursday, May 4, 2023 at 09:24:35 AM PDT, Charlie England <ceengland7(at)gmail.com> wrote:                 
                  
 
                  
 
                  It is common practice with a/c audio wires, but it rarely does anything helpful. The reason  is that a/c audio is 'low impedance'; around 600 ohms, and is far less susceptible to picking up radiated noise than the wiring in a home stereo, where the low level stuff is ~50k ohms impedance. 
 
 Similar situation with data. I wonder if the mfgrs of avionics are just hoping that one more layer of 'stuff' may head off a service complaint.
 
 Charlie
 Audio tech, and service tech, in a couple of past lives
 
 On Thu, May 4, 2023 at 11:06 AM Jeff Luckey <jluckey(at)pacbell.net (jluckey(at)pacbell.net)> wrote:
  	  | Quote: | 	 		  
          I will throw in one asterisk *  ...
 
 Many Avionics manufacturers recommend the use of shielded cables for their data bus wiring.
 
  OK, 2 asterisks...
 
 Also, it is fairly common practice to shield low-level audio wires.
 -Jeff
 
                   
                                                                     On Thursday, May 4, 2023 at 08:51:49 AM PDT, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:                 
                  
                  
                    At 03:51 AM 5/4/2023, you wrote:  	  | Quote: | 	 		  | --> AeroElectric-List message posted by: "Area-51" <goldsteinindustrial(at)gmail.com (goldsteinindustrial(at)gmail.com)> Thanks guys for all the input there... | 	        	  | Quote: | 	 		  | I would not feel convinced with silver coated traces; its a great conductor but brittle over time. | 	      The use of silver plating on Teflon insulated    wires is necessary because of high extrusion    temperatures for Teflon . . . not for improved    conductivity. Tinned conductors are not compatible    with Teflon insulation.  	  | Quote: | 	 		  | I thought shielding is required to mitigate RF generated interference to avionics?? | 	      Please review the chapter in the 'Connection on    electro-magnetic compatibility practice. Ideally,    the well crafted installation of qualified    appliances in airplanes (or any other vehicle)    do not require shielding of any kind. You    will be hard pressed to find a shielded wire    in any system in your car . . . or TC aircraft.    They are rare.    I can't remember the last time I found it    necessary to shield any wire.  
     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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		Ceengland
 
 
  Joined: 11 Oct 2020 Posts: 394 Location: MS
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				 Posted: Thu May 04, 2023 9:42 am    Post subject: Wiring Looms | 
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				If one is buying brand new avionics       with a bunch of digits to the left of the decimal point, then       obviously it makes sense to follow the mfgr's installation       instructions, for exactly that reason.
        
        But now we're talking about what works for 'interpersonal       relations'; not what works.
         
        
        On 5/4/2023 11:42 AM, Jeff Luckey wrote:
      
       	  | Quote: | 	 		                         Interesting observations.            But from a practical point of view...
          
          
          Charlie, that may be the           case, but I would not want to be in a situation where           something is not working correctly, possibly due to some kind           of interference, and having to explain to manufacturer's tech           support that I did not comply with their recommended           procedures.  It could give them license to say: "Well it's on           you, then".
          
          
          Same thing goes for           customers.  I would have trouble trying to explain to a           customer why I didn't comply with the manufacturer's           recommendations.
          
          
          
          
          -Jeff
          
          
        
                             On Thursday, May 4, 2023 at 09:24:35 AM PDT, Charlie             England <ceengland7(at)gmail.com> (ceengland7(at)gmail.com) wrote: 
            
            
            
            
                                                                                                 It is common                       practice with a/c audio wires, but it rarely does                       anything helpful. The reason  is that a/c audio is                       'low impedance'; around 600 ohms, and is far less                       susceptible to picking up radiated noise than the                       wiring in a home stereo, where the low level stuff                       is ~50k ohms impedance. 
                                           
                      Similar                       situation with data. I wonder if the mfgrs of                       avionics are just hoping that one more                       layer of 'stuff' may head off a service complaint.
                                           
                      Charlie
                      Audio tech, and                       service tech, in a couple of past lives
                    
                                                                                   On                         Thu, May 4, 2023 at 11:06 AM Jeff Luckey <jluckey(at)pacbell.net (jluckey(at)pacbell.net)>                         wrote:                       
                         	  | Quote: | 	 		                                                                                   I will throw in one asterisk                               *  ...
                                                           
                              Many Avionics manufacturers                               recommend the use of shielded cables for                               their data bus wiring.
                                                           
                               OK, 2 asterisks...
                                                           
                              Also, it is fairly common                               practice to shield low-level audio wires.
                                                           
                                                           
                              -Jeff
                                                           
                                                           
                                                           
                            
                                                                                         On Thursday, May 4, 2023 at 08:51:49                                 AM PDT, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>                                 wrote: 
                                                               
                                                               
                                                                                                                                         At 03:51 AM 5/4/2023,                                       you wrote:                                                                           	  | Quote: | 	 		  | -->                                       AeroElectric-List message                                       posted by: "Area-51"                                       <goldsteinindustrial(at)gmail.com (goldsteinindustrial(at)gmail.com)>                                                                              Thanks guys for all the input                                       there... | 	                                                                                                                                                          	  | Quote: | 	 		  | I would not                                       feel convinced with                                       silver coated traces; its a great                                       conductor but brittle over                                       time. | 	                                                                               The use of silver plating on                                     Teflon insulated                                        wires is necessary because of                                     high extrusion                                        temperatures for Teflon . . . not                                     for improved                                        conductivity. Tinned conductors                                     are not compatible                                        with Teflon insulation.                                                                           	  | Quote: | 	 		  | I thought                                       shielding is required                                       to mitigate RF generated                                       interference to avionics?? | 	                                                                               Please review the chapter in the                                     'Connection on                                        electro-magnetic compatibility                                     practice. Ideally,                                        the well crafted installation of                                     qualified                                        appliances in airplanes (or any                                     other vehicle)                                        do not require shielding of any                                     kind. You                                        will be hard pressed to find a                                     shielded wire                                        in any system in your car . . .                                     or TC aircraft.                                        They are rare.                                                                             I can't remember the last time I                                     found it                                        necessary to shield any wire.                                                                                                               
    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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		Area-51
 
 
  Joined: 03 May 2021 Posts: 439
 
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				 Posted: Thu May 04, 2023 11:23 am    Post subject: Re: Wiring Looms | 
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				This is really interesting now! 🤓
 
 When i did the nervous system for a mustang project everything was twisted pairs throughout, except the loom between electric steering control box and steering rack, and GPS antenna; which were both twisted pair and shielded.
 
 Makes sense that RF comes from AC and not DC current flow 🤔
 
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		nuckolls.bob(at)aeroelect Guest
 
 
 
 
 
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				 Posted: Mon May 08, 2023 7:15 am    Post subject: Wiring Looms | 
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				At 11:01 AM 5/4/2023, you wrote:
   	  | Quote: | 	 		  I will throw in one asterisk *  ...
 
  Many Avionics manufacturers recommend the use of shielded cables for their data bus wiring.
 
   OK, 2 asterisks...
 
  Also, it is fairly common practice to shield low-level audio wires. | 	  
    If these techniques are necessary for the
    system to achieve design goals then the
    manufacturer's instructions will say so
    and their wiring diagrams will illustrate
    it.
 
    Had a builder show up at one of my seminars
    out in California waaayyy back when showing
    off pictures of his LongEz project. He was
    rather proud of the wiring . . . he advised
    that he used shielded wire for everything.
    I asked if he was having a noise problem and
    he advised, 'no, the airplane isn't flying yet'.
    
    The $, weight and time expended on this
    endeavor would have been much better spent
    elsewhere. The the physics that defines the
    necessity for shielding is simple. If it's
    not on the instructions, it's not necessary.
 
  
  
    Bob . . .
 
                     //// 
                    (o o) 
     ===========o00o=(_)=o00o========= 
     < Go ahead, make my day . . .   > 
     < show me where I'm wrong.      > 
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     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
 
 
 
 
 
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				 Posted: Mon May 08, 2023 7:22 am    Post subject: Wiring Looms | 
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				 	  | Quote: | 	 		  
  Similar situation with data. I wonder if the mfgrs of avionics
  are just hoping that one more layer of 'stuff' may head off a service complaint. | 	  
     Hope doesn't get you very far in the TC
     aircraft world. DO160 and similar documents
     call out a constellation of laboratory tests
     to verify that an appliance is going to be
     well behaved in the ship's electronic community.
 
     The qualification tests demonstrate
     resistance to expected, external stimuli
     as well as freedom from generating 'noises' that
     put other systems at risk.
 
     If the drawings do (or do not) show shielding,
     then you can bet there is a good reason for
     it.
 
  
    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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