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Ground Wire for Starter Contactor?

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tinnemaha(at)hotmail.com
Guest

Posted: Sat Oct 14, 2006 4:58 am Post subject: Ground Wire for Starter Contactor?

Hi List,



I followed the Z-11 diagram for my simple system & see that the starter 

contactor has a 'firewall ground'.  To me, that means it grounds through the 

stainless steel firewall it is mounted on.  Indeed, that is what my ohmeter 

says & I'm confident it will perform fine (As I'm not flying yet & haven't 

quite fired up the engine yet, I haven't actually seen the contactor work)  

However, this seems to conflict with the single point ground idea basic to 

Bob's philosophy.  My starter contactor is the only component of my system 

without a dedicated wire running to the forest of ground tabs.



Any experienced advice or opinions on this?



I've been absent the list for a long time & couldn't find anything on this 

in the archives.  Hope you haven't already gone over it a hundred times.



Thanks,

Grant

nuckollsr(at)cox.net
Guest

Posted: Sat Oct 14, 2006 9:45 am Post subject: Ground Wire for Starter Contactor?

At 05:57 AM 10/14/2006 -0700, you wrote:



 	  Quote: 	
		  



Hi List,



I followed the Z-11 diagram for my simple system & see that the starter 

contactor has a 'firewall ground'.  To me, that means it grounds through 

the stainless steel firewall it is mounted on.  Indeed, that is what my 

ohmeter says & I'm confident it will perform fine (As I'm not flying yet & 

haven't quite fired up the engine yet, I haven't actually seen the 

contactor work)

However, this seems to conflict with the single point ground idea basic to 

Bob's philosophy.  My starter contactor is the only component of my system 

without a dedicated wire running to the forest of ground tabs.



Any experienced advice or opinions on this?



I've been absent the list for a long time & couldn't find anything on this 

in the archives.  Hope you haven't already gone over it a hundred times.


	


   The commonly utilized automotive starter contactors

   do get a ground for the coil through the base provided

   that the firewall sheet is metallic and your system

   has a firewall ground stud and forest-of-tabs for

   other systems.



   This is fine as installed. The contactor is VERY

   intermittent duty and is neither a potential victim

   nor potential antagonist for ground-loop coupled

   noises. I guess I should add "starter contactors" to

   the list of items that integrate nicely into airplanes

   using LOCAL grounds.



   Bob . . .



      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

rv8ch

Joined: 10 Jan 2006
Posts: 250
Location: Switzerland

Posted: Sat Oct 14, 2006 10:22 am Post subject: Ground Wire for Starter Contactor?

 	  Quote: 	
		     The commonly utilized automotive starter contactors

   do get a ground for the coil through the base provided

   that the firewall sheet is metallic and your system

   has a firewall ground stud and forest-of-tabs for

   other systems.


	


Sorry I may have missed it, but did we ever get to the bottom of why the 

"newer" B&C battery contactors have rubber boots on the mounting tabs? 

If we have that model, should we remove the boots, or otherwise ground 

the contactor?



Thanks,

Mickey



-- 

Mickey Coggins

http://www.rv8.ch/

#82007 finishing

do not archive

_________________
Mickey Coggins
http://www.rv8.ch/

nuckollsr(at)cox.net
Guest

Posted: Sat Oct 14, 2006 10:44 am Post subject: Ground Wire for Starter Contactor?

At 08:20 PM 10/14/2006 +0200, you wrote:



 	  Quote: 	
		  

<mick-matronics(at)rv8.ch>



>   The commonly utilized automotive starter contactors

>   do get a ground for the coil through the base provided

>   that the firewall sheet is metallic and your system

>   has a firewall ground stud and forest-of-tabs for

>   other systems.



Sorry I may have missed it, but did we ever get to the bottom of why the 

"newer" B&C battery contactors have rubber boots on the mounting tabs? If 

we have that model, should we remove the boots, or otherwise ground the 

contactor?


	


   Never did see any documents or conversation that

   explained why the boots were added and/or considered

   a good thing to do under any circumstances. I'm

   thinking we're on firm ground to recommend removal

   for installation under the prevailing philosophy.



   Bob . . .



      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

dsvs(at)comcast.net
Guest

Posted: Sat Oct 14, 2006 6:51 pm Post subject: Ground Wire for Starter Contactor?

--

nuckollsr(at)cox.net
Guest

Posted: Sat Oct 14, 2006 7:13 pm Post subject: Ground Wire for Starter Contactor?

 	  Quote: 	
		  

    Never did see any documents or conversation that

    explained why the boots were added and/or considered

    a good thing to do under any circumstances. I'm

    thinking we're on firm ground to recommend removal

    for installation under the prevailing philosophy.



    Bob . . .



     I tried to get the "boots" off and gave up.  I think they are oin to

stay. Any good ideas as to how to remove them?


	


   Hmmmm . . . I guess I've never seen them either. Got

   a digital camera? Send me some pictures. I note that

   B&C is still using the pictures I took.



   Bob . . .

dsvs(at)comcast.net
Guest

Posted: Sat Oct 14, 2006 7:57 pm Post subject: Ground Wire for Starter Contactor?

--

nuckollsr(at)cox.net
Guest

Posted: Sun Oct 15, 2006 7:41 am Post subject: Ground Wire for Starter Contactor?

 	  Quote: 	
		  

 >

 >     I tried to get the "boots" off and gave up.  I think they are oin to

 >stay. Any good ideas as to how to remove them?



    Hmmmm . . . I guess I've never seen them either. Got

    a digital camera? Send me some pictures. I note that

    B&C is still using the pictures I took.



    Bob . . .



Will try to take some tomorrow.  The contactor is mounted and I am not sure

that I can get a good enough shot to show any thing about the boot

attachment.  They appear to be molded on and I think the legs were drilled

to allow the molding to form pass a through to hold them on.


	


   Did you get it from B&C? I'll call them tomorrow and

   see if they'll send me a sample.



   Bob . . .

dsvs(at)comcast.net
Guest

Posted: Sun Oct 15, 2006 6:34 pm Post subject: Ground Wire for Starter Contactor?

--

jack.byrne(at)bigpond.com
Guest

Posted: Tue Oct 17, 2006 12:55 pm Post subject: Ground Wire for Starter Contactor?

Bob



What was the out come of the molded rubber boots?

I actually have the S701-2 and have reconfigured the jumpers to the S701-1

configuration. I figured the actual contactors are one and the same.



The boots are on there to stay (grinder will be required) and there is no

way the contactor will get a ground with them on. Are you still recommending

to grind them off?

Can the case be grounded by running a wire to the gnd forest of tabs. If so

what size wire. The contactor is mounted on a composite firewall 2' from the

tabs. Starter contactor is on the firewall side which grounds through the

stainless firewall. If the boots come off the contactor will ground through

the firewall via the starter mounting bolts (starter contactor and battery

contactor mounted back to back)

Thanks Bob.



Chris Byrne

SYDNEY

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