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recapen(at)earthlink.net
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 Posted: Wed Jan 06, 2016 10:30 am Post subject: Grounding Tabs |
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I ran as much as I could to the forest of tabs....if there's a grounding issue, I know where to look for the broken wire.....
Also, I am hopefully preventing ground loops - and energizing the skin.....
YMMV
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Paul Valovich
Joined: 11 Jan 2006
Posts: 75
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| Posted: Thu Jan 07, 2016 6:24 am Post subject: Grounding Tabs |
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In my RV-8A I used the forward baggage bin for fuze and grounding blocks. Still had the shelf for baggage. I connected two ground tabs blocks – one aft and one forward of the firewall, then connected that via welding cable to the engine.
Rather than run relatively big wires back through the cockpit, I used local grounds for pitot heat, flaps and strobes.
Paul Valovich
N192NM 650+ hrs
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nuckolls.bob(at)aeroelect
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| Posted: Thu Jan 07, 2016 5:27 pm Post subject: Grounding Tabs |
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At 12:03 PM 1/6/2016, you wrote:
| Quote: | | I am currently wiring my RV8. I plan on using a "forest of Tabs" for almost all of my grounding, Avionics, EFIS, Lights, Pumps flaps etc. Because of the location of the forward baggage compartment on the RV8, it is not really practical have the tabs on the firewall. I have a forward battery and have a brass bolt connecting the Neg. lead and engine grounding strap to the firewall. What I plan to do is run a #6 cable from there to the "forest of tabs" mounted on the bulkhead behind the instrument panel. I plan to insulate the brass plate and tabs form the bulkhead so all the grounding will go directly to the brass bolt in the firewall. This way there is a true single point grounding. It also makes for a nice clean instillation. I have read the Aero Electric book several times and will probably never fully understand ground loops. So here are my questions. |
Study Figure z-15 of the 'Connection" at
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z15K1.pdf
and . . .
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z15K3p1.pdf
Then see if your questions are answered or in need of
adjustment . . .
Generally speaking, PANEL and AIRFRAME systems congregate
at their own central locations. They get tied together with
a single conductor of appropriate size and integrity.
Bob . . .
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fvalarm(at)rapidnet.net
Guest
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| Posted: Thu Jan 07, 2016 11:50 pm Post subject: Grounding Tabs |
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I did what I believe you are proposing. There will be a lot of ground wires to terminate. I filled two forest of tabs. One on the firewall with the pass-through bolt for the battery neg to connect to. The other just behind the instrument panel with a #6 wire joining them for good measure (and a little extra weight  ).
Bevan
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Michael Lazarowicz
Sent: Thursday, January 07, 2016 6:03 PM
To: aeroelectric-list(at)matronics.com
Subject: Re: Grounding Tabs
I think my question may be in need of adjustment. I pretty much get the do not s of grounding the headphones locally. But my question still is If I need to move the forest of tabs off the firewall by way of a large gauge wire because I really can't or do not like running all my no avionics stuff like cockpit lights, fuel pumps, panned lights to a local ground. Does it make sense to use the same gauge wire (in this case #6) to relocate the forest of tabs away from the firewall. My engine and battery are connected to the firewall with the 5/16 brass bolt. The 6 gauge wire to the grounding tabs are also connected to the same brass firewall bolt. I will have a few grounds locally lights etc. but really like the single point Idea. Because of the G3x system engine sensor ho0kup there is virtually nothing to ground on the firewall side.
I am pretty much a dummy on this stuff and was given your book from my life long friend who runs Central States Ass. Terry, Schubert. If It was a Canard EZ I would be in great shape. Unfortunately since I am building a "span can" its different.
On Thu, Jan 7, 2016 at 8:26 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 12:03 PM 1/6/2016, you wrote:
| Quote: | | I am currently wiring my RV8. I plan on using a "forest of Tabs" for almost all of my grounding, Avionics, EFIS, Lights, Pumps flaps etc. Because of the location of the forward baggage compartment on the RV8, it is not really practical have the tabs on the firewall. I have a forward battery and have a brass bolt connecting the Neg. lead and engine grounding strap to the firewall. What I plan to do is run a #6 cable from there to the "forest of tabs" mounted on the bulkhead behind the instrument panel. I plan to insulate the brass plate and tabs form the bulkhead so all the grounding will go directly to the brass bolt in the firewall. This way there is a true single point grounding. It also makes for a nice clean instillation. I have read the Aero Electric book several times and will probably never fully understand ground loops. So here are my questions. |
Study Figure z-15 of the 'Connection" at
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z15K1.pdf
and . . .
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z15K3p1.pdf
Then see if your questions are answered or in need of
adjustment . . .
Generally speaking, PANEL and AIRFRAME systems congregate
at their own central locations. They get tied together with
a single conductor of appropriate size and integrity.
Bob . . .
|
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fvalarm(at)rapidnet.net
Guest
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| Posted: Thu Jan 07, 2016 11:51 pm Post subject: Grounding Tabs |
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I forgot to mention, that this has been working very well with no strange electrical noises in the headsets when strobes, flap motors etc are turned on. So I'm a very happy camper.
Bevan
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Michael Lazarowicz
Sent: Thursday, January 07, 2016 6:03 PM
To: aeroelectric-list(at)matronics.com
Subject: Re: Grounding Tabs
I think my question may be in need of adjustment. I pretty much get the do not s of grounding the headphones locally. But my question still is If I need to move the forest of tabs off the firewall by way of a large gauge wire because I really can't or do not like running all my no avionics stuff like cockpit lights, fuel pumps, panned lights to a local ground. Does it make sense to use the same gauge wire (in this case #6) to relocate the forest of tabs away from the firewall. My engine and battery are connected to the firewall with the 5/16 brass bolt. The 6 gauge wire to the grounding tabs are also connected to the same brass firewall bolt. I will have a few grounds locally lights etc. but really like the single point Idea. Because of the G3x system engine sensor ho0kup there is virtually nothing to ground on the firewall side.
I am pretty much a dummy on this stuff and was given your book from my life long friend who runs Central States Ass. Terry, Schubert. If It was a Canard EZ I would be in great shape. Unfortunately since I am building a "span can" its different.
On Thu, Jan 7, 2016 at 8:26 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 12:03 PM 1/6/2016, you wrote:
| Quote: | | I am currently wiring my RV8. I plan on using a "forest of Tabs" for almost all of my grounding, Avionics, EFIS, Lights, Pumps flaps etc. Because of the location of the forward baggage compartment on the RV8, it is not really practical have the tabs on the firewall. I have a forward battery and have a brass bolt connecting the Neg. lead and engine grounding strap to the firewall. What I plan to do is run a #6 cable from there to the "forest of tabs" mounted on the bulkhead behind the instrument panel. I plan to insulate the brass plate and tabs form the bulkhead so all the grounding will go directly to the brass bolt in the firewall. This way there is a true single point grounding. It also makes for a nice clean instillation. I have read the Aero Electric book several times and will probably never fully understand ground loops. So here are my questions. |
Study Figure z-15 of the 'Connection" at
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z15K1.pdf
and . . .
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z15K3p1.pdf
Then see if your questions are answered or in need of
adjustment . . .
Generally speaking, PANEL and AIRFRAME systems congregate
at their own central locations. They get tied together with
a single conductor of appropriate size and integrity.
Bob . . .
|
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Sat Jan 09, 2016 11:06 am Post subject: Grounding Tabs |
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At 08:03 PM 1/7/2016, you wrote:
| Quote: | I think my question may be in need of adjustment. I pretty much get the do not s of grounding the headphones locally. But my question still is If I need to move the forest of tabs off the firewall by way of a large gauge wire because I really can't or do not like running all my no avionics stuff like cockpit lights, fuel pumps, panned lights to a local ground. Does it make sense to use the same gauge wire (in this case #6) to relocate the forest of tabs away from the firewall.  My engine and battery are connected to the firewall with the 5/16 brass bolt. The 6 gauge wire to the grounding tabs are also connected to the same brass firewall bolt. I will have a few grounds locally lights etc. but really like the single point Idea. Because of the G3x system engine sensor ho0kup there is virtually nothing to ground on the firewall side.
I am pretty much a dummy on this stuff and was given your book from my life long friend who runs Central States Ass. Terry, Schubert. If It was a Canard EZ I would be in great shape. Unfortunately since I am building a "span can" its different.   |
The only time you run wire between grounding features for
the purpose of achieving a common ground is when only
one of those features is fastened to the airframe. As
Figures Z-15 shows, the ideal location for the forest
of tabs is on the firewall where battery(-) and engine
crankcase come to a single point airframe airframe ground.
Panel avionics ground need not all run to that point
as individual conductors. You gather those wires together
locally on the panel with an avionics grounding feature
and then extend that feature to the firewall ground
with a robust conductor . . . 10 or 12 awg is
suggested.
So it sounds like you don't even need a forest of
tabs at the firewall . . . just the ground stud
to handle battery and crankcase grounds. Then
use the smaller, more compact grounding hardware
to gather up avionics and bring them to that same
stud.
Bob . . .
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billbear
Joined: 26 Oct 2012
Posts: 7
Location: Alasska
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| Posted: Sat Jan 09, 2016 12:30 pm Post subject: Grounding Tabs |
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Bob,
When another “grounding bus” is used, like an avionics ground bus or a “panel” ground bus, is it necessary to isolate/insolate that ground bus from the “local” ground, or other metal frame on the aircraft, before it is connected to the common firewall ground? It seems to me that you should do that to eliminate other possibilities of ground loops.
Bill Bear
On Jan 9, 2016, at 5:41, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 08:03 PM 1/7/2016, you wrote:
| Quote: | I think my question may be in need of adjustment. I pretty much get the do not s of grounding the headphones locally. But my question still is If I need to move the forest of tabs off the firewall by way of a large gauge wire because I really can't or do not like running all my no avionics stuff like cockpit lights, fuel pumps, panned lights to a local ground. Does it make sense to use the same gauge wire (in this case #6) to relocate the forest of tabs away from the firewall.  My engine and battery are connected to the firewall with the 5/16 brass bolt. The 6 gauge wire to the grounding tabs are also connected to the same brass firewall bolt. I will have a few grounds locally lights etc. but really like the single point Idea. Because of the G3x system engine sensor ho0kup there is virtually nothing to ground on the firewall side.
I am pretty much a dummy on this stuff and was given your book from my life long friend who runs Central States Ass. Terry, Schubert. If It was a Canard EZ I would be in great shape. Unfortunately since I am building a "span can" its different.   |
The only time you run wire between grounding features for
the purpose of achieving a common ground is when only
one of those features is fastened to the airframe. As
Figures Z-15 shows, the ideal location for the forest
of tabs is on the firewall where battery(-) and engine
crankcase come to a single point airframe airframe ground.
Panel avionics ground need not all run to that point
as individual conductors. You gather those wires together
locally on the panel with an avionics grounding feature
and then extend that feature to the firewall ground
with a robust conductor . . . 10 or 12 awg is
suggested.
So it sounds like you don't even need a forest of
tabs at the firewall . . . just the ground stud
to handle battery and crankcase grounds. Then
use the smaller, more compact grounding hardware
to gather up avionics and bring them to that same
stud.
Bob . . .
|
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Sat Jan 09, 2016 1:15 pm Post subject: Grounding Tabs |
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At 02:28 PM 1/9/2016, you wrote:
| Quote: | Bob,
When another “grounding bus” is used, like an avionics ground bus or a “panel” ground bus, is it necessary to isolate/insolate that ground bus from the “local” ground, or other metal frame on the aircraft, before it is connected to the common firewall ground? It seems to me that you should do that to eliminate other possibilities of ground loops. |
I'm going to clarify Z-15 in next revision . . .
you're correct that running a ground from
panel ground to firewall ground is redundant in a metal
airplane. It doesn't hurt anything as long as all
the potential victims (avionics and instruments)
ground at the single point panel ground. No
potentially antagonist loops are created by adding
a wire to the firewall . . . it's just redundant.
Bob . . .
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handainc(at)madisoncounty
Guest
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| Posted: Sat Jan 09, 2016 1:58 pm Post subject: Grounding Tabs |
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Bob - I think you answered only half the question. Is it better to isolate the grounding buss, and run a dedicated ground back to the firewall ground, or mount the ground buss to the airframe, and not run a wire back to to the firewall ground? In a metal airplane. Are you more apt to have possible ground loops if you mount the buss to the airframe than you would isolating it from the airframe and running the ground wire back to the firewall ground?
M. Haught
| Quote: | On Jan 9, 2016, at 3:14 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
At 02:28 PM 1/9/2016, you wrote: | Quote: | | Bob, When another “grounding bus” is used, like an avionics ground bus or a “panel” ground bus, is it necessary to isolate/isolate that ground bus from the “local” ground, or other metal frame on the aircraft, before it is connected to the common firewall ground? It seems to me that you should do that to eliminate other possibilities of ground loops. |
I'm going to clarify Z-15 in next revision . . . you're correct that running a ground from panel ground to firewall ground is redundant in a metal airplane. It doesn't hurt anything as long as all the potential victims (avionics and instruments) ground at the single point panel ground. No potentially antagonist loops are created by adding a wire to the firewall . . . it's just redundant.
Bob . . .
|
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theidtke(at)cox.net
Guest
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| Posted: Sun Jan 10, 2016 7:05 am Post subject: Grounding Tabs |
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Marvin,
You might find a good explanation and tips in the Wiring For Smart People document included as a link here.  http://www.meyette.us/aircraft_wiring12july2008.pdf
I found it very useful when wiring my plane. If I did it/read it right, the answer to your question is to isolate the grounding buss and take a lead back to the main battery and/or battery buss.
Just my two cents…..
Trent
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of H. Marvin Haught
Sent: Saturday, January 09, 2016 2:57 PM
To: aeroelectric-list(at)matronics.com
Subject: Re: Grounding Tabs
Bob - I think you answered only half the question. Is it better to isolate the grounding buss, and run a dedicated ground back to the firewall ground, or mount the ground buss to the airframe, and not run a wire back to to the firewall ground? In a metal airplane. Are you more apt to have possible ground loops if you mount the buss to the airframe than you would isolating it from the airframe and running the ground wire back to the firewall ground?
M. Haught
| Quote: |
On Jan 9, 2016, at 3:14 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
At 02:28 PM 1/9/2016, you wrote:
Bob,
When another “grounding bus” is used, like an avionics ground bus or a “panel” ground bus, is it necessary to isolate/isolate that ground bus from the “local” ground, or other metal frame on the aircraft, before it is connected to the common firewall ground? It seems to me that you should do that to eliminate other possibilities of ground loops.
I'm going to clarify Z-15 in next revision . . .
you're correct that running a ground from
panel ground to firewall ground is redundant in a metal
airplane. It doesn't hurt anything as long as all
the potential victims (avionics and instruments)
ground at the single point panel ground. No
potentially antagonist loops are created by adding
a wire to the firewall . . . it's just redundant.
Bob . . .
|
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ceengland7(at)gmail.com
Guest
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| Posted: Sun Jan 10, 2016 8:20 am Post subject: Grounding Tabs |
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There's probably some useful info there, but keep your salt shaker handy.
Charlie
On 1/10/2016 9:03 AM, Trent Heidtke wrote:
| Quote: | <![endif]--> <![endif]-->
Marvin,
You might find a good explanation and tips in the Wiring For Smart People document included as a link here.  http://www.meyette.us/aircraft_wiring12july2008.pdf
I found it very useful when wiring my plane. If I did it/read it right, the answer to your question is to isolate the grounding buss and take a lead back to the main battery and/or battery buss.
Just my two cents…..
Trent
Â
From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] On Behalf Of H. Marvin Haught
Sent: Saturday, January 09, 2016 2:57 PM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Subject: Re: Grounding Tabs
Â
Bob - Â I think you answered only half the question. Â Is it better to isolate the grounding buss, and run a dedicated ground back to the firewall ground, or mount the ground buss to the airframe, and not run a wire back to to the firewall ground? Â In a metal airplane. Â Are you more apt to have possible ground loops if you mount the buss to the airframe than you would isolating it from the airframe and running the ground wire back to the firewall ground? Â
Â
M. Haught
Â
 | Quote: |
On Jan 9, 2016, at 3:14 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Â
At 02:28 PM 1/9/2016, you wrote:
Bob,
When another “grounding bus” is used, like an avionics ground bus or a “panel” ground bus, is it necessary to isolate/isolate that ground bus from the “local” ground, or other metal frame on the aircraft, before it is connected to the common firewall ground? It seems to me that you should do that to eliminate other possibilities of ground loops.
  I'm going to clarify Z-15 in next revision . . .
  you're correct that running a ground from
  panel ground to firewall ground is redundant in a metal
  airplane. It doesn't hurt anything as long as all
  the potential victims (avionics and instruments)
  ground at the single point panel ground. No
  potentially antagonist loops are created by adding
  a wire to the firewall . . . it's just redundant.
 Bob . . .
|
Â
|
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jmjones2000(at)mindspring
Guest
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| Posted: Sun Jan 10, 2016 8:54 am Post subject: Grounding Tabs |
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I think the can of worms was just reopened.
There is some correct information in this document but there is a whole lot of opinions. The document was written by Greg from the now-defunct Blue Mountain Avionics.
Bob has attempted to have an open discussion on some of the points that Greg has attempted to make, but from what I recall, Greg wasn't interested in the discussion for one reason or another. I will let Bob elaborate.
Just a few rhetorical questions about some of the points he made.... Why would you want two batteries (or one 24v) and not two alternators? What if the belt driving the alternator breaks or the bearing in the alternator causes it to fail? Or the alternator fails? Or the regulator fails... With an electrically dependent engine, hack the clock as your airborne time is now limited. With a second alternator (perhaps driven from the vacuum pad) you now have a non-event and lower risk of an impending engine failure due to running out of stored electrons.
There are many more issues with the document that I won't go into, however some of the information is factually correct.
Be careful out there. The Internet is full of potentially bad information.
Justin
On Jan 10, 2016, at 07:03, Trent Heidtke <theidtke(at)cox.net (theidtke(at)cox.net)> wrote:
| Quote: | <![endif]--> <![endif]-->
Marvin,
You might find a good explanation and tips in the Wiring For Smart People document included as a link here. http://www.meyette.us/aircraft_wiring12july2008.pdf
I found it very useful when wiring my plane. If I did it/read it right, the answer to your question is to isolate the grounding buss and take a lead back to the main battery and/or battery buss.
Just my two cents…..
Trent
|
| Quote: |
From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] On Behalf Of H. Marvin Haught
Sent: Saturday, January 09, 2016 2:57 PM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Subject: Re: AeroElectric-List: Grounding Tabs
Bob - I think you answered only half the question. Is it better to isolate the grounding buss, and run a dedicated ground back to the firewall ground, or mount the ground buss to the airframe, and not run a wire back to to the firewall ground? In a metal airplane. Are you more apt to have possible ground loops if you mount the buss to the airframe than you would isolating it from the airframe and running the ground wire back to the firewall ground?
M. Haught
| Quote: |
On Jan 9, 2016, at 3:14 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
At 02:28 PM 1/9/2016, you wrote:
Bob,
When another “grounding bus” is used, like an avionics ground bus or a “panel” ground bus, is it necessary to isolate/isolate that ground bus from the “local” ground, or other metal frame on the aircraft, before it is connected to the common firewall ground? It seems to me that you should do that to eliminate other possibilities of ground loops.
I'm going to clarify Z-15 in next revision . . .
you're correct that running a ground from
panel ground to firewall ground is redundant in a metal
airplane. It doesn't hurt anything as long as all
the potential victims (avionics and instruments)
ground at the single point panel ground. No
potentially antagonist loops are created by adding
a wire to the firewall . . . it's just redundant.
Bob . . .
|
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nuckolls.bob(at)aeroelect
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| Posted: Sun Jan 10, 2016 9:36 am Post subject: Grounding Tabs |
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At 03:57 PM 1/9/2016, you wrote:
| Quote: | | Bob - I think you answered only half the question. Is it better to isolate the grounding buss, and run a dedicated ground back to the firewall ground, or mount the ground buss to the airframe, and not run a wire back to to the firewall ground? |
In the metal airplane, grounding all panel mounted
systems to panel structure is sufficient . . . no
'extension' wire to the firewall is useful . . . nor
is it a potential 'loop hazard'.
| Quote: | | In a metal airplane. Are you more apt to have possible ground loops if you mount the buss to the airframe than you would isolating it from the airframe and running the ground wire back to the firewall ground? |
No . . . the 'loop' exists when a potential
antagonist (alternator, battery charging
currents, flap motors, strobe supplies, etc)
SHARES a grounding pathway with the low voltage
signals of a potential victim (headphones, microphones,
intercoms, remote compass sensors, etc).
Tie all potential victims to ground at one place
local to the panel . . . after that, signal integrity
is no longer 'at risk' no matter how and where
you ground all other things,
Bob . . .
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nuckolls.bob(at)aeroelect
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| Posted: Sun Jan 10, 2016 9:48 am Post subject: Grounding Tabs |
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At 09:03 AM 1/10/2016, you wrote:
| Quote: | Marvin,
You might find a good explanation and tips in the Wiring For Smart People document included as a link here.  http://www.meyette.us/aircraft_wiring12july2008.pdf
I found it very useful when wiring my plane. If I did it/read it right, the answer to your question is to isolate the grounding buss and take a lead back to the main battery and/or battery buss. |
Approach that document with caution . . . it
is fraught with error and unfounded assertions.
See:
http://tinyurl.com/qxvr6nx
Bob . . .
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wtmills
Joined: 05 Feb 2007
Posts: 32
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| Posted: Sun Jan 10, 2016 10:08 am Post subject: Grounding Tabs |
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Well said Charlie.
Do not archive
Bill
Sent via the Samsung Galaxy Note® II, an AT&T 4G LTE smartphone
-------- Original message --------
From: Charlie England
Date:01/10/2016 7:30 AM (GMT-08:00)
To: aeroelectric-list(at)matronics.com
Subject: Re: AeroElectric-List: Grounding Tabs
There's probably some useful info there, but keep your salt shaker handy.
Charlie
On 1/10/2016 9:03 AM, Trent Heidtke wrote:
| Quote: | <![endif]--> <![endif]-->
Marvin,
You might find a good explanation and tips in the Wiring For Smart People document included as a link here. [/url][url=http://www.meyette.us/aircraft_wiring12july2008.pdf]http://www.meyette.us/aircraft_wiring12july2008.pdf
I found it very useful when wiring my plane. If I did it/read it right, the answer to your question is to isolate the grounding buss and take a lead back to the main battery and/or battery buss.
Just my two cents…..
Trent
From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] On Behalf Of H. Marvin Haught
Sent: Saturday, January 09, 2016 2:57 PM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Subject: Re: AeroElectric-List: Grounding Tabs
Bob - I think you answered only half the question. Is it better to isolate the grounding buss, and run a dedicated ground back to the firewall ground, or mount the ground buss to the airframe, and not run a wire back to to the firewall ground? In a metal airplane. Are you more apt to have possible ground loops if you mount the buss to the airframe than you would isolating it from the airframe and running the ground wire back to the firewall ground?
M. Haught
| Quote: |
On Jan 9, 2016, at 3:14 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
At 02:28 PM 1/9/2016, you wrote:
Bob,
When another “grounding bus” is used, like an avionics ground bus or a “panel” ground bus, is it necessary to isolate/isolate that ground bus from the “local” ground, or other metal frame on the aircraft, before it is connected to the common firewall ground? It seems to me that you should do that to eliminate other possibilities of ground loops.
I'm going to clarify Z-15 in next revision . . .
you're correct that running a ground from
panel ground to firewall ground is redundant in a metal
airplane. It doesn't hurt anything as long as all
the potential victims (avionics and instruments)
ground at the single point panel ground. No
potentially antagonist loops are created by adding
a wire to the firewall . . . it's just redundant.
Bob . . .
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handainc(at)madisoncounty
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| Posted: Sun Jan 10, 2016 10:34 am Post subject: Grounding Tabs |
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Okay.....I think I finally understand. I was making it a lot more complex that it really is, at least for a metal airframe. The airframe itself is a good basic ground for all components as long as you have good grounding points for the firewall/airframe/engine, and good common airframe ground for panel components. So for wing tip mounted strobes, the airframe ground is sufficient? No need to run a ground wire back to the firewall ground to avoid interference?
M. Haught
On 1/10/2016 10:45 AM, Robert L. Nuckolls, III wrote:
| Quote: | At 03:57 PM 1/9/2016, you wrote:
| Quote: | | Bob - I think you answered only half the question. Is it better to isolate the grounding buss, and run a dedicated ground back to the firewall ground, or mount the ground buss to the airframe, and not run a wire back to to the firewall ground? |
In the metal airplane, grounding all panel mounted
systems to panel structure is sufficient . . . no
'extension' wire to the firewall is useful . . . nor
is it a potential 'loop hazard'.
| Quote: | | In a metal airplane. Are you more apt to have possible ground loops if you mount the buss to the airframe than you would isolating it from the airframe and running the ground wire back to the firewall ground? |
No . . . the 'loop' exists when a potential
antagonist (alternator, battery charging
currents, flap motors, strobe supplies, etc)
SHARES a grounding pathway with the low voltage
signals of a potential victim (headphones, microphones,
intercoms, remote compass sensors, etc).
Tie all potential victims to ground at one place
local to the panel . . . after that, signal integrity
is no longer 'at risk' no matter how and where
you ground all other things,
Bob . . . |
 This email has been sent from a virus-free computer protected by Avast. www.avast.com
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Sun Jan 10, 2016 3:50 pm Post subject: Grounding Tabs |
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At 12:22 PM 1/10/2016, you wrote:
| Quote: | | Okay.....I think I finally understand. I was making it a lot more complex that it really is, at least for a metal airframe. The airframe itself is a good basic ground for all components as long as you have good grounding points for the firewall/airframe/engine, and good common airframe ground for panel components. So for wing tip mounted strobes, the airframe ground is sufficient? No need to run a ground wire back to the firewall ground to avoid interference? |
No
Bob . . .
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jimbean6(at)optimum.net
Guest
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| Posted: Tue Jan 12, 2016 12:41 pm Post subject: Grounding Tabs |
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I don't see why you say it is not practical to mount on the firewall.
My 8 has tabs on both sides of the firewall with a big brass bolt
through the whole thing that picks
up the engine ground strap. They are just below the baggage compartment
floor.
Worked for me.
cheers Jim Bean
Time: 12:36:37 PM PST US
Subject: Re: Returned Mail: Re: Grounding Tabs
From: Michael Lazarowicz
Thanks Bob. I will use the Forest of Tabs. Like I said in
previous post.
It is not Practical in the RV 8 to locate the forest on the
firewall so it
will be mounted on the bulkhead behind the panel ( Isolated from
that thin
bulkhead and I will ground everything I can to those tabs. I
will use a #6
wire to connect that to the firewall/batter/engine strap bolt. I
guess my
confusion is Z-15 Shows all " panel grounds " in one place and
all
firewall grounds in another. I just wondered if by sharing that
#6 wire to
the firewall I would cause a problem?
Thanks for your patience
On Sun, Jan 10, 2016 at 6:55 PM, Robert L. Nuckolls, III <
nuckolls.bob(at)aeroelectric.com> wrote:
> At 04:35 PM 1/10/2016, you wrote:
>
> I have read Bob's reply.=C3=82 It raises another
question.=C3=82 If I w
ere to use
> B&C forest of tabs to ground everything.=C3=82 Flap motor , P.
Heat,=C3
=82 strobes,
> interior lights and all the panel stuff like coms, audio panel
etc.=C3=82
would
> that cause a ground loop.
>
>
> No . . . the "ideal" single point ground philosophy
> says take EVERYTHING to one place . . . except for
> the simplest of small airplanes, this is impractical.
>
> As shown in the Z-15 figures, collect all panel grounds
> (potential victims) to one place, all airframe grounds
> to firewall as practical . . . or ground locally as
> convenience dictates.
>
> For plastic airplanes, then -A- you DO gather airframe
grounds to
> the firewall and -B- take an extension wire from
> the panel ground down to the firewall.
>
> Bob . . .
>
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Tue Jan 12, 2016 2:31 pm Post subject: Grounding Tabs |
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At 02:36 PM 1/12/2016, you wrote:
| Quote: | --> AeroElectric-List message posted by: James Bean <jimbean6(at)optimum.net>
I don't see why you say it is not practical to mount on the firewall. |
. . . if you've got something like a Kitfox with
a few day/vfr avionics and the panel hardware
is close to the firewall ground . . . then it's easy.
But if you have a LAIVP with a panel full of electron
herders and byte thrashers, it's not so practical to
run a BUNDLE of shield, audio, power and signal grounds
up to the firewall. Then it makes more sense to
gather all those things up AT THE PANEL then, if
a plastic airplane, EXTEND the panel ground to the
firewall on a suitable conductor. If a metal airplane,
then no extension is necessary or helpful.
Bob . . .
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