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Grounding Questions

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art(at)zemon.name
Guest

Posted: Sun Jul 31, 2016 5:20 am Post subject: Grounding Questions

Folks, 

I am planning the wiring for stuff that goes in the wings of my plane and wondering about how to properly ground it. The plane is a BD-4C, metal, high wing. The salient points are: 

1) The wings are removable and will come off during each annual, which means I will build a wiring harness that goes from the back of the instrument panel to a connector at the wing root, and

 2) I need to run the wires through a conduit inside 2x2 inch channel to get from the top of the cabin to behind the instrument panel. 

I see several choices: 

I could ground everything to the airframe in the wing and trust the the wing spar makes an electrically sound connection when I install the wing. I don't like this idea, even though it would probably be fine. 

I could run a ground wire for each device from the wing root connector to the grounding block behind the instrument panel. E.g., a wire from the left position/strobe light, a second wire from the right position/strobe light, etc. 

I could combine the grounds for "like devices." E.g., combineÂ  the grounds for the position/strobe lights in both wings, combineÂ  the grounds for the fuel senders in both wings, and combine the grounds for the landing lights in both wings. 

I could combine all of the grounds at the wing root and run a single wire to the grounding block behind the instrument panel. 

What thoughts do you have? Thanks. 

Â Â Â  -- Art Z. 

http://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

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Sun Jul 31, 2016 6:28 am Post subject: Grounding Questions

I think you are overly obsessing the issue. All of your wing electrics 

are resistive loads, not radio frequency gizmos. You might gain a 

smidgeon of accuracy in the fuel sender with a separate ground, but 

separate grounds for all the rest won't make a hoot of difference. Make 

a ground connection from wing root to fuselage near wing root. Ground 

each item locally in the wing. No need to run separate wire from wing 

root to your central ground point. You could run a separate ground for 

the fuel sender to central ground, but not likely to make a noticeable 

difference. TC aircraft use local grounds for all that stuff.

You don't say if you plan traditional nav and strobe lights or LEDs. I 

recommend the latter for lower current draw and no need for a high 

voltage strobe power supply, and mostly eliminates the one RFI noise 

source in wings. LEDs will be similar in cost for quality units, so 

money isn't much of a factor.



On 7/31/2016 6:18 AM, Art Zemon wrote:

 	  Quote: 	
		   Folks,



 I am planning the wiring for stuff that goes in the wings of my plane

 and wondering about how to properly ground it. The plane is a BD-4C,

 metal, high wing. The salient points are:



 1) The wings are removable and will come off during each annual, which

 means I will build a wiring harness that goes from the back of the

 instrument panel to a connector at the wing root, and

 2) I need to run the wires through a conduit inside 2x2 inch channel to

 get from the top of the cabin to behind the instrument panel.



 I see several choices:



 I could ground everything to the airframe in the wing and trust the the

 wing spar makes an electrically sound connection when I install the

 wing. I don't like this idea, even though it would /probably/ be fine.



 I could run a ground wire for each device from the wing root connector

 to the grounding block behind the instrument panel. E.g., a wire from

 the left position/strobe light, a second wire from the right

 position/strobe light, etc.



 I could combine the grounds for "like devices." E.g., combine  the

 grounds for the position/strobe lights in both wings, combine  the

 grounds for the fuel senders in both wings, and combine the grounds for

 the landing lights in both wings.



 I could combine all of the grounds at the wing root and run a single

 wire to the grounding block behind the instrument panel.



 What thoughts do you have? Thanks.



     -- Art Z.



 http://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

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

cluros(at)gmail.com
Guest

Posted: Sun Jul 31, 2016 8:30 am Post subject: Grounding Questions

Hi Art. Everything on my BD-4 wingtips is grounded to the wing spar with no difficulties. I think your spar is a much better ground than any wire could be as far as lights and pitot heat. You're adding weight and complexity to no purpose. Drill a hole in the end of each spar and put a nutplate or rivet nut in. 

I would definitely run wires to your single point ground for the fuel gauges. My wing is fibreglass and the fuel gauges were grounded to the fuse and a little corrosion on the ring terminal was enough to throw them off significantly.

Also leave plenty of extra wire in the wings for when you take them off. It's awful having to remove a wing to plug a wire back in that you pulled loose removing a wingtip. I would leave an extra 2-3' sticking out of the wing tip and an extra 3' at the wing root. Remember as you pull the wings off the distance gets almost 2 feet longer before the wing comes off and you can unplug the wire.



Sebastien



On Jul 31, 2016, at 09:18, Art Zemon <art(at)zemon.name (art(at)zemon.name)> wrote:

 	  Quote: 	
		  

Folks, 

I am planning the wiring for stuff that goes in the wings of my plane and wondering about how to properly ground it. The plane is a BD-4C, metal, high wing. The salient points are: 

1) The wings are removable and will come off during each annual, which means I will build a wiring harness that goes from the back of the instrument panel to a connector at the wing root, and

 2) I need to run the wires through a conduit inside 2x2 inch channel to get from the top of the cabin to behind the instrument panel. 

I see several choices: 

I could ground everything to the airframe in the wing and trust the the wing spar makes an electrically sound connection when I install the wing. I don't like this idea, even though it would probably be fine. 

I could run a ground wire for each device from the wing root connector to the grounding block behind the instrument panel. E.g., a wire from the left position/strobe light, a second wire from the right position/strobe light, etc. 

I could combine the grounds for "like devices." E.g., combine  the grounds for the position/strobe lights in both wings, combine  the grounds for the fuel senders in both wings, and combine the grounds for the landing lights in both wings. 

I could combine all of the grounds at the wing root and run a single wire to the grounding block behind the instrument panel. 

What thoughts do you have? Thanks. 

    -- Art Z. 

http://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

ceengland7(at)gmail.com
Guest

Posted: Sun Jul 31, 2016 9:17 am Post subject: Grounding Questions

I'd agree, but I'd avoid rivnuts like       the plague they are. I've never met a rivnut that didn't spin. If       you use 'em, at some point you'll be fighting to get the screw out       so you can drill them out to replace with plate nuts.

       

       On 7/31/2016 11:28 AM, Sebastien wrote:

     

      	  Quote: 	
		                Hi Art. Everything on my BD-4 wingtips is grounded to the         wing spar with no difficulties. I think your spar is a much         better ground than any wire could be as far as lights and pitot         heat. You're adding weight and complexity to no purpose. Drill a         hole in the end of each spar and put a nutplate or rivet nut         in.Â 

       

       

       I would definitely run wires to your single point ground for         the fuel gauges. My wing is fibreglass and the fuel gauges were         grounded to the fuse and a little corrosion on the ring terminal         was enough to throw them off significantly.

       

       

       Also leave plenty of extra wire in the wings for when you         take them off. It's awful having to remove a wing to plug a wire         back in that you pulled loose removing a wingtip. I would leave         an extra 2-3' sticking out of the wing tip and an extra 3' at         the wing root. Remember as you pull the wings off the distance         gets almost 2 feet longer before the wing comes off and you can         unplug the wire.

         

         Sebastien

       

         On Jul 31, 2016, at 09:18, Art Zemon <art(at)zemon.name (art(at)zemon.name)>         wrote:

         

       

        	  Quote: 	
		                      

Folks,           

I am planning the wiring for stuff that goes in             the wings of my plane and wondering about how to properly             ground it. The plane is a BD-4C, metal, high wing. The             salient points are:           

1) The wings are removable and will come off             during each annual, which means I will build a wiring             harness that goes from the back of the instrument panel to a             connector at the wing root, and

             2) I need to run the wires through a conduit inside 2x2 inch             channel to get from the top of the cabin to behind the             instrument panel.           

I see several choices:           

I could ground everything to the airframe in the             wing and trust the the wing spar makes an electrically sound             connection when I install the wing. I don't like this idea,             even though it would probably be fine.           

I could run a ground wire for each device from             the wing root connector to the grounding block behind the             instrument panel. E.g., a wire from the left position/strobe             light, a second wire from the right position/strobe light,             etc.           

I could combine the grounds for "like devices."             E.g., combineÂ  the grounds for the position/strobe lights in             both wings, combineÂ  the grounds for the fuel senders in             both wings, and combine the grounds for the landing lights             in both wings.           

I could combine all of the grounds at the wing             root and run a single wire to the grounding block behind the             instrument panel.           

What thoughts do you have? Thanks.           

Â Â Â  -- Art Z.           

http://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

art(at)zemon.name
Guest

Posted: Sun Jul 31, 2016 11:13 am Post subject: Grounding Questions

Kelly & Sebastien & Charlie,

Thanks for your suggestions. How does this wiring plan look to you?

â€‹

Â strobe position lights.pdf

â€‹



Be nice, please. It's my first attempt at a wiring diagram. 



Â  Â  -- Art Z.



-- 

http://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

cluros(at)gmail.com
Guest

Posted: Sun Jul 31, 2016 12:40 pm Post subject: Grounding Questions

Art,

Looks good except all your Local Grounds from the wing spar and carry through are unnecessary. The spar grounds itself to the carry through quite well even when coated with oil. Obviously anything mounted in the fiberglass wingtips will need a ground wire connected to the spar at the tip end.

Are you planning on using shielded wire in the spar or count on the spar to be your shielding? You might want to use shielded wire from the panel to the first connector as the installation instructions suggest. Further than that I'm not sure it would add anything and connecting the shield to ground might be problematic. You need to keep the in-spar connector as simple as possible to make wing removal and installation as simple and safe as possible. Remember to make sure the wire from the panel hangs out the carry through a MINIMUM of one foot.



Sebastien



On Jul 31, 2016, at 15:11, Art Zemon <art(at)zemon.name (art(at)zemon.name)> wrote:

 	  Quote: 	
		  Kelly & Sebastien & Charlie,

Thanks for your suggestions. How does this wiring plan look to you?

â€‹

 strobe position lights.pdf

â€‹



Be nice, please. It's my first attempt at a wiring diagram. 



    -- Art Z.



-- 

http://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

cluros(at)gmail.com
Guest

Posted: Sun Jul 31, 2016 12:48 pm Post subject: Grounding Questions

Also is the red box in your diagram a connector or the nav strobe unit itself? If the latter you will need to add a connector at the tip end of the spar so that you can disconnect the light for wing tip removal. Make sure you have enough slack in the wires so that the connectors hang out a foot from both the spar and the wing tip each. 



Sebastien



On Jul 31, 2016, at 15:11, Art Zemon <art(at)zemon.name (art(at)zemon.name)> wrote:

 	  Quote: 	
		  Kelly & Sebastien & Charlie,

Thanks for your suggestions. How does this wiring plan look to you?

â€‹

 strobe position lights.pdf

â€‹



Be nice, please. It's my first attempt at a wiring diagram. 



    -- Art Z.



-- 

http://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

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jul 31, 2016 2:06 pm Post subject: Grounding Questions

At 03:38 PM 7/31/2016, you wrote:

  	  Quote: 	
		  Art,



 Looks good except all your Local Grounds from the wing spar and carry through are unnecessary. The spar grounds itself to the carry through quite well even when coated with oil. Obviously anything mounted in the fiberglass wingtips will need a ground wire connected to the spar at the tip end.



 Are you planning on using shielded wire in the spar or count on the spar to be your shielding? You might want to use shielded wire from the panel to the first connector as the installation instructions suggest. Further than that I'm not sure it would add anything and connecting the shield to ground might be problematic. You need to keep the in-spar connector as simple as possible to make wing removal and installation as simple and safe as possible. Remember to make sure the wire from the panel hangs out the carry through a MINIMUM of one foot. 	




   That's what I would do if it were my airplane . . .



 

 

   Bob . . .

art(at)zemon.name
Guest

Posted: Sun Jul 31, 2016 6:12 pm Post subject: Grounding Questions

Sebastien & Bob,



Thank you for your suggestions. I shielded the strobe wire between the switch and the spar tube. I left the wires running inside the spar tube unshielded.

I don't know what the red box represents because all I have right now is the installation doc, no hardware. I added connectors at the wing tips to the drawing, just in case the red box is not a connector of some sort. And I will definitely be sure that I have nice long service loops for removing the wings and the wing tips.

Here is the updated drawing.Â â€‹

Â strobe position lights.pdf

â€‹



Cheers,

Â  Â  -- Art Z.

On Sun, Jul 31, 2016 at 3:38 PM, Sebastien <cluros(at)gmail.com (cluros(at)gmail.com)> wrote:

 	  Quote: 	
		  Art,

Looks good except all your Local Grounds from the wing spar and carry through are unnecessary. The spar grounds itself to the carry through quite well even when coated with oil. Obviously anything mounted in the fiberglass wingtips will need a ground wire connected to the spar at the tip end.

Are you planning on using shielded wire in the spar or count on the spar to be your shielding? You might want to use shielded wire from the panel to the first connector as the installation instructions suggest. Further than that I'm not sure it would add anything and connecting the shield to ground might be problematic. You need to keep the in-spar connector as simple as possible to make wing removal and installation as simple and safe as possible. Remember to make sure the wire from the panel hangs out the carry through a MINIMUM of one foot.



Sebastien



On Jul 31, 2016, at 15:11, Art Zemon <art(at)zemon.name (art(at)zemon.name)> wrote:

 	  Quote: 	
		  Kelly & Sebastien & Charlie,

Thanks for your suggestions. How does this wiring plan look to you?

â€‹

Â strobe position lights.pdf

â€‹



Be nice, please. It's my first attempt at a wiring diagram. 



Â  Â  -- Art Z.



-- 

http://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

 



 

	


	




-- 

http://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

cluros(at)gmail.com
Guest

Posted: Sun Jul 31, 2016 6:27 pm Post subject: Grounding Questions

Looks great Art. 



Sebastien



On Jul 31, 2016, at 22:09, Art Zemon <art(at)zemon.name (art(at)zemon.name)> wrote:

 	  Quote: 	
		  Sebastien & Bob,



Thank you for your suggestions. I shielded the strobe wire between the switch and the spar tube. I left the wires running inside the spar tube unshielded.

I don't know what the red box represents because all I have right now is the installation doc, no hardware. I added connectors at the wing tips to the drawing, just in case the red box is not a connector of some sort. And I will definitely be sure that I have nice long service loops for removing the wings and the wing tips.

Here is the updated drawing. â€‹

 strobe position lights.pdf

â€‹



Cheers,

    -- Art Z.

On Sun, Jul 31, 2016 at 3:38 PM, Sebastien <cluros(at)gmail.com (cluros(at)gmail.com)> wrote:

 	  Quote: 	
		  Art,

Looks good except all your Local Grounds from the wing spar and carry through are unnecessary. The spar grounds itself to the carry through quite well even when coated with oil. Obviously anything mounted in the fiberglass wingtips will need a ground wire connected to the spar at the tip end.

Are you planning on using shielded wire in the spar or count on the spar to be your shielding? You might want to use shielded wire from the panel to the first connector as the installation instructions suggest. Further than that I'm not sure it would add anything and connecting the shield to ground might be problematic. You need to keep the in-spar connector as simple as possible to make wing removal and installation as simple and safe as possible. Remember to make sure the wire from the panel hangs out the carry through a MINIMUM of one foot.



Sebastien



On Jul 31, 2016, at 15:11, Art Zemon <art(at)zemon.name (art(at)zemon.name)> wrote:

 	  Quote: 	
		  Kelly & Sebastien & Charlie,

Thanks for your suggestions. How does this wiring plan look to you?

â€‹

 strobe position lights.pdf

â€‹



Be nice, please. It's my first attempt at a wiring diagram. 



    -- Art Z.



-- 

http://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

 



 

	


	




-- 

http://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

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