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TWISTED PAIRS

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John M Tipton

Joined: 07 Aug 2018
Posts: 45
Location: Devon - England

Posted: Wed May 01, 2019 7:43 am Post subject: TWISTED PAIRS

Hi Guys (Bob)



When a twisted pair is required (eg: Power and ground to Radio), do you take both back to the fuse panel, then lead off the ground wire to the ground block  ( which is a return route - L form) or lead off the ground wire to the ground block en route (it's only half distance to the ground block - ie: T form)



To clarify: the route to the ground block is 15 inches and to the Fuse bus 30 inches.



Regards



John

nuckolls.bob(at)aeroelect
Guest

Posted: Wed May 01, 2019 1:37 pm Post subject: TWISTED PAIRS

At 10:43 AM 5/1/2019, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "John M Tipton" <john(at)tiptonuk.eu>



 Hi Guys (Bob)



 When a twisted pair is required (eg: Power and ground to Radio), do you take both back to the fuse panel, then lead off the ground wire to the ground block  ( which is a return route - L form) or lead off the ground wire to the ground block en route (it's only half distance to the ground block - ie: T form)



 To clarify: the route to the ground block is 15 inches and to the Fuse bus 30 inches. 	


   I can't imagine why anyone would twist

   the ground and power wires on any device

   (other than the illumination lamp to a

   whisky compass up on the windshield).



   What's the product and what, if any, reason

   is given in instructions for doing this

   to the wires?



 

 

   Bob . . .

jim(at)PoogieBearRanch.co
Guest

Posted: Wed May 01, 2019 3:19 pm Post subject: TWISTED PAIRS

Doesn't the remote panel switch for ELTs generally specify the use of

twisted-pair wiring?  Seems like I recall seeing that when I was

considering replacing my ELT.  

Jim Parker



------

art(at)zemon.name
Guest

Posted: Wed May 01, 2019 4:02 pm Post subject: TWISTED PAIRS

My Artex did not



    -- Art Z.



Sent from my phone. Please excuse brevity and bizarre typos.

On Wed, May 1, 2019, 6:34 PM  <jim(at)poogiebearranch.com (jim(at)poogiebearranch.com)> wrote:



[quote]--> AeroElectric-List message posted by: <jim(at)poogiebearranch.com (jim(at)poogiebearranch.com)>

 

 Doesn't the remote panel switch for ELTs generally specify the use of

 twisted-pair wiring?  Seems like I recall seeing that when I was

 considering replacing my ELT.  

 

 

 Jim Parker

 

 ------

John M Tipton

Joined: 07 Aug 2018
Posts: 45
Location: Devon - England

Posted: Thu May 02, 2019 1:07 am Post subject: Re: TWISTED PAIRS

Hi Bob



Here is an example of twisted pairs (even twisted trio) you asked for my EZpilot (A/p):



file:///C:/Users/John%20Tipton/Downloads/EZ%20Pilot%20Manual%20rev%202.5%20.pdf



I hope that works and it on page 36:



Regards



John

John M Tipton

Joined: 07 Aug 2018
Posts: 45
Location: Devon - England

Posted: Thu May 02, 2019 1:11 am Post subject: Re: TWISTED PAIRS

Hi Bob



Try this:



https://www.trioavionics.com/EZ%20Pilot%20Manual%20rev%202.5%20.pdf



Page 36



John

nuckolls.bob(at)aeroelect
Guest

Posted: Thu May 02, 2019 5:06 am Post subject: TWISTED PAIRS

At 06:18 PM 5/1/2019, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: <jim(at)poogiebearranch.com>



 Doesn't the remote panel switch for ELTs generally specify the use of

 twisted-pair wiring?  Seems like I recall seeing that when I was

 considering replacing my ELT. 	


   Could be . . . and I too have suggested it for situations

   where one is building a long run of 2 or more wires. I've

   often used a drill motor to build an independent bundle

   of wires, usually small (22 or 20AWG max) that all terminated

   in the same place.



   Twisting is, at best, a matter of craftsmanship/convenience.

   A bundle of wires in a 'straight lay' is stiff while

   a twisted array remains flexible while physically

   constrained in a handy bundle. When building pendant

   cables for ground test equipment, I often twist the

   array of wires before pulling them through a 'snake

   skin' . . . makes for a really compliant test tool.

  

   Mitigation of magnetic/electro-static coupling by twisting

   SEEMS like a good idea . . . except that those coupling

   modes are exceedingly weak and practical ONLY when the

   pair to be twisting is either a STRONG potential antagonist

   or VULNERABLE victim.



   The DC power leads are NOT potential antagonists

   nor are they vulnerable.



   The fact that either of these conditions

   is a consideration for integrating a particular

   electro-whizzy into your airplane is a CONFESSION

   of poor attention to details . . . like Mil-Std-704,

   DO-160, etc . . . or a lack of understanding.



   It's like the ol' avionics master switch meme intended

   to ward off evil, non-existent 'spikes' while cranking

   an engine. Once planted, it will grow and thrive like

   an intellectual fungus long after advances in understanding

   and application of the SCIENCE has shown it to be floobydust.



   The short answer is: when your electro-whizzy's installation

   manual calls for twisting for 'noise' or avionics master switch

   for 'spikes', a healthy dose of skepticism is called for. 

   



 

 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Thu May 02, 2019 5:26 am Post subject: TWISTED PAIRS

At 04:07 AM 5/2/2019, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "John M Tipton" <john(at)tiptonuk.eu>



 Hi Bob



 Here is an example of twisted pairs (even twisted trio) you asked for my EZpilot (A/p):



 [url=file://C:\Users\John%2520Tipton\Downloads\EZ%2520Pilot%2520Manual%2520rev%25202.5%2520.pdf] file:///C:/Users/John%20Tipton/Downloads/EZ%20Pilot%20Manual%20rev%202.5%20.pdf[/url] 



 I hope that works and it on page 36: 	


   The folks who wrote this did a better

   than average job, but their lack of

   experience in air-frame wiring is

   obvious.



   The narrative about wire sizes is

   startling. 24AWG wire in an airframe

   is more difficult to work with . . .

   26AWG would NOT be recommended.

   I would not suggest such a thing for

   OBAM aircraft and would think LONG

   and HARD before calling it out in

   a TC aircraft.



   Premier (B390) airframe wiring used

   a lot of 24 . . . but this was a 'busy'

   airplane with miles of wire in it.

   Weight savings was significant. But

   the people who had to work with it

   on the line and in the field were

   less than enthusiastic.



   Our airplanes (with mere dozens of

   feet of wire), hooking up with

   smaller than 22AWG is of no practical

   benefit.



   The shielded trios use to wire the

   servos is handy from a fabrication/

   installation perspective. The

   EMC considerations for using

   a shielded trio may be (but

   unlikely) valid. But using off-

   the-spool, pre-twisted, pre-twisted,

   shielded wire is very convenient.



 

 

   Bob . . .

echristley(at)att.net
Guest

Posted: Thu May 02, 2019 6:19 am Post subject: TWISTED PAIRS

I like to twist power and ground for organizational reasons.  It just cleans up the installation.



                  

                                                                    On Wednesday, May 1, 2019, 5:38:13 PM EDT, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com> wrote:                 

                 



                 



                   At 10:43 AM 5/1/2019, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "John M Tipton" <john(at)tiptonuk.eu>



 Hi Guys (Bob)



 When a twisted pair is required (eg: Power and ground to Radio), do you take both back to the fuse panel, then lead off the ground wire to the ground block  ( which is a return route - L form) or lead off the ground wire to the ground block en route (it's only half distance to the ground block - ie: T form)



 To clarify: the route to the ground block is 15 inches and to the Fuse bus 30 inches. 	


   I can't imagine why anyone would twist

   the ground and power wires on any device

   (other than the illumination lamp to a

   whisky compass up on the windshield).



   What's the product and what, if any, reason

   is given in instructions for doing this

   to the wires?



 

 

    Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Thu May 02, 2019 6:54 am Post subject: TWISTED PAIRS

At 09:18 AM 5/2/2019, you wrote:

  	  Quote: 	
		  I like to twist power and ground for organizational reasons.  It just cleans up the installation. 	


   Hear hear! 



 

 

   Bob . . .

art(at)zemon.name
Guest

Posted: Thu May 02, 2019 4:58 pm Post subject: TWISTED PAIRS

I didn't twist much of anything. I used red and black wire and laced the bundles. It ended up looking nice and the lacing was peaceful, satisfying work.



I did twist the wires for my OAT probe and that was just to make the pair easier to handle since it runs the length of the fuselage.



    -- Art Z.



Sent from my phone. Please excuse brevity and bizarre typos.

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