REFLECTOR: Wiring in ducts

[Al Gietzen]

Subject: Re: REFLECTOR: Wiring in ducts

 

The question is:  Do the wires running close to the fat wires to/from the
alternator pick up stray electrical noise?  That might make them unsuitable
for instrumentation!

 

Keith

 

Having put an oscilloscope on the alternator output and seen the noise; I
would definitely suggest separating low voltage/current signal wires. The
degree to which it could affect a particular signal of course depends on the
signal, but why take a chance.  The noise from the alternator (or other high
intermittent current leads propagates throughout the power distribution.  

 

Al

 

  _____  

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Nate Jackson
Sent: Sunday, July 02, 2006 8:52 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Wiring in ducts

 

Keith,

 

I haven't needed it yet, but I laid various gages of extra wire down the
co-pilot side.  It's coiled up behind carpet in the front and behind the aft
bullheads.  Yes... a little extra weight.

 

Nate

RG Elite/IVO

----- Original Message ----- 

From: Keith <mailto:KeithHallsten at quiknet.com>  Hallsten 

To: Velocity <mailto:reflector at tvbf.org>  Aircraft Owners and Builders list 

Sent: Sunday, July 02, 2006 7:49 PM

Subject: REFLECTOR: Wiring in ducts

 

I'm about to start pulling wire, and wanted to ask whether anyone has run
engine instrumentation wiring in the same duct as the big #2 alternator
feed/starter/engine ground wires.  I know that it's considered good practice
to separate the fat conductors from the little wires, in order to keep the
noisy big currents, alternator whine and associated magnetic fields away
from the signal wires.  

However, I'm not enthusiastic about running either type of wires through the
pilot's-side duct with the oil cooler lines.  I'm afraid that long term
exposure to the high temperatures will tend to cook the insulation.  I'm
going to be running a lot of thermocouple wires, pressure and temperature
signal wires, capacitive fuel gauge lines, and tach pulse lead up to the
Grand Rapids EIS 6000 engine monitor in the panel.  I don't know if the
potential electrical noise or the heat of the oil cooler lines will be the
bigger threat to their function and life.  So I'm undecided which is likely
to be the better scheme.  What say you?

Keith Hallsten

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