Hi! Tony.
Can it be said for "big fat wire"( below) read 14 gauge is OK ?
The negative bus is connected to the Battery main cable supply point through
a 12" length of 14 gauge wire.
regards
Bob H G-PTAG
-----Original Message-----
From: forum-owner@europaclub.org.uk
Subject: Re: Bundling of coax cables
So a "negative" bus bar, with about a dozen connections, should be
thrown and replaced with a single point connection for all the "circuit"
return wires ,as well as a single point connection for the "grounding "
wires? (Just convince me please that circuit negative wires are the same
or different to "ground" wires?) Regards Bob
A negative bus bar is a single point ground if all of your
ground/negative wires terminate on the bar. If all your wiring
terminates on this single bus bar then you have the best form of ground
return other than terminating all of the wires at the battery.
The key is to have all the circuit return wires terminate at as few
(preferably one) point on the aircraft and to have minimal resistance
(read big fat wire)to the current source return (battery). This single
point can be a bus bar, a bolt or a plate with connectors. The point
here is that the resistance between the individual return line
termination points should be very, very low and a block of brass bus bar
does this very nicely.
Circuit negative wires are the same as ground wires which are the same
as return wires.
On a tin can aircraft the skin and structure effectively can act as a
very large single point ground with the return current flowing over the
entire skin. As it's a massive area electrically the current flow per sq
cm is miniscule. Composite aircraft don't have the luxury of having this
cheap return path so we have to build an individual return path for each
and every circuit. Unfortunately electricity has the habit of finding
the easiest path to ground and, if the returns form multiple paths to
grounds and there is a variation in resistance of those return lines,
then voltage differences can be induced between the ground points as the
current flows between them. Bringing all return lines to a single point
and ensuring that the single point has a low resistance to the aircraft
true ground point removes the problem.
I have built several large computer controlled model railway systems
over the years which have amazing parallels to wiring the aircraft.
Failure to bring the grounds back to a single point in those systems can
induce so much electrical noise that the microelectronics simply fails
to work.
Tony
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