Today's Message Index:
----------------------
1. 11:06 AM - Re: Grounding Tabs (Robert L. Nuckolls, III)
2. 12:30 PM - Re: Grounding Tabs (Bill Bear)
3. 01:15 PM - Re: Grounding Tabs (Robert L. Nuckolls, III)
4. 01:58 PM - Re: Grounding Tabs (H. Marvin Haught)
Message 1
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| Subject: | Re: Grounding Tabs |
At 08:03 PM 1/7/2016, you wrote:
>I think my question may be in need of
>adjustment.=C2 I pretty much get the do not s of
>grounding the headphones locally.=C2 But my
>question still is If=C2 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,=C2 fuel pumps, panned lights to a local
>ground. Does it make sense to use the same gauge
>wire=C2 (in this case #6) to relocate the forest
>of tabs away from the firewall.=C2 =C2 My engine
>and battery are connected to the firewall with
>the 5/16 brass bolt.=C2 The 6 gauge wire to the
>grounding tabs are also connected to the same
>brass firewall bolt.=C2 I will have a few grounds
>locally lights etc. but really like the single
>point Idea.=C2 Because of the G3x system engine
>sensor ho0kup=C2 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.=C2 If
>It was a Canard EZ I would be in great
>shape.=C2 Unfortunately since I am building a "span can" its different.
=C2 =C2
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 . . .
Message 2
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| Subject: | Re: Grounding Tabs |
Bob,
When another =93grounding bus=94 is used, like an avionics ground bus or
a =93panel=94 ground bus, is it necessary to isolate/insolate that
ground bus from the =93local=94 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@aeroelectric.com> wrote:
> At 08:03 PM 1/7/2016, you wrote:
>> I think my question may be in need of adjustment.=C2 I pretty much
get the do not s of grounding the headphones locally.=C2 But my
question still is If=C2 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,=C2 fuel
pumps, panned lights to a local ground. Does it make sense to use the
same gauge wire=C2 (in this case #6) to relocate the forest of tabs
away from the firewall.=C2 =C2 My engine and battery are connected to
the firewall with the 5/16 brass bolt.=C2 The 6 gauge wire to the
grounding tabs are also connected to the same brass firewall bolt.=C2 I
will have a few grounds locally lights etc. but really like the single
point Idea.=C2 Because of the G3x system engine sensor ho0kup=C2 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.=C2 If
It was a Canard EZ I would be in great shape.=C2 Unfortunately since I
am building a "span can" its different. =C2 =C2
>
> 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 . . .
>
Message 3
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| Subject: | Re: Grounding Tabs |
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/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 . . .
Message 4
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| 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
> On Jan 9, 2016, at 3:14 PM, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
>
> At 02:28 PM 1/9/2016, you wrote:
>> Bob,
>>
>> When another =C2=93grounding bus=C2=94 is used, like an avionics
ground bus or a =C2=93panel=C2=94 ground bus, is it necessary to
isolate/isolate that ground bus from the =C2=93local=C2=94 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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