On 29 Oct 2014, at 16:01, Steven Pitt <steven.pitt2@ntlworld.com> wrote:
> Ira/Ferg/Peter
> Your input came at just the moment I am rewiring my radio and transponder
> equipment
for mode S and 8.33khz and I was reviewing my ground/earth installation.
> As a non aviation electrician I have always been confused by these concepts
> and
the issue of earth loops so can I ask for clarification.
> Shielded wire for the mikes and phones are shown as connected in the Trig
> diagrams
so that suggests to me that connecting them all together and then running
one wire back to the battery negative contact would be the way to go.
> But then what about the ground strap to the engine block and the PTT wires
> which
are shown as 'earthed'. How can you do that in a plastic aircraft.
> Sorry if this is really basic and although I have been flying for 8 years in
'DH I have always been uncertain that I had wired up the grounds correctly.
Steve - you can get good advice about this and many other aeroplane wiring
issues
---From 'Lectric Bob. His website is at:
http://www.aeroelectric.com
Many years ago I purchased a paper copy of the AeroElectric Connection which
helped
me translate many of the principles I already knew as an
electrical/electronic/audio
engineer into practical guidelines for wiring my aircraft.
You can get the publication on paper or CD-ROM, or you can just wade into the
Matronics
AeroElectric list and start asking questions.
You can also see how I planned my own electrical installation at:
http://www.rowlandcarson.org.uk/aviation/europa_435/wirebook.php
There are many references in my diagrams to common earth either cockpit side or
engine side. This is a couple of stout metal plates fastened together through
the firewall, with many tabs on each side for 1/4 blade connectors, and a big
terminal to connect to the battery negative.
B & C Speciality makes this item and you can see it at:
http://www.bandc.biz/grounding-supplies-battery-cables.aspx
In UK, Airworld stocks it:
http://shop.airworlduk.com/ground-bus-2448-position-300941-367-p.asp
Everything that requires to be earthed or grounded has a wire running all the
way
back to that block of tabs. On my main circuit diagram (based on the one in
the Europa build manual) a line marked ground return busbar is shown. To match
the physical reality, that should really be shown as a single point, but that
would make the diagram very messy.
Hope this helps.
in friendship
Rowland
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