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Which wire size ?

Larry DeCamp

Well Known Member
Garmin instructions suggest all DB connectors can be wired with 24 AWG or 22 AWG . Is there any rationale that would discourage using 22 AWG exclusively for all ? This would obviously minimize inventory and simplify the process.

As a result of my ignorance, I used 20 AWG thermocouple extension for Alcor sensors because they came with short 20 AWG wires. The 20 AWG fits in the pins used in the GEA24. Any reason not to just build on with my Daniels crimp tool ?
 
I have found that the maximum wire size that can be used in the High Density D sub connector pins and sockets is 22AWG.

The Standard Density pins and sockets will accept 20AWG. Just be sure to set the Daniels crimper to the correct wire size.

There are times when using the 74 position HD connectors, and all positions are wired and populated, that it is easier to get all the wires through the D-shell housing and strain relief if the smaller size wire is used. The PS Engineering Audio Panel comes to mind.
 
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either or

I used all 24 gauge for shielded signal wires. I found them much easier to fit in the limited bulkhead holes to the rear of my RV-10. I have the GTX45R, GTR20, GSA28 pitch servo and GMU11 not to mention elevator and rudder trim, tail strobe, battery and rudder beacon in the back. Lots of wires to run past the spar carry through in very limited holes. Oh, and I almost forgot, two coax antenna wires as well.

That being said, 24 gauge is mighty small and required extra care and cheater glassed to terminate. From what I read and others have recommended over the years #22 is easier to work with and just fine in function. It is just a little larger in diameter to pull through the holes.

The different dies for the Daniels crimper are needed based on the low/high density pins not the wire size. Wire size is just an adjustment on the crimper settings.
 
I do not use #24 wire anywhere - other than four conductor shielded wire for headphone jacks, ADS-B receiver, trim motors and such. I consider #24 to be too fragile for aircraft use unless it is part of a shielded wire assembly.

If you are doing a standard install (as in no analog CDI and such) you will only use a fraction of the pins on the back of something like a GTN-650, so no need to worry about bundle size getting big. I used a total of 43 pins on my last GTN-650 install that went with a dual SkyView panel.

Carl
 
Larry, my fellow RV-3 brethren,

I use 22 or 24 gauge twisted shielded wire for data and audio purposes and 20 or 22 gauge bare wire for power and ground runs at the panel avionics. I try to use shielded wire for power to sensitive remote LRUs like magnetometers and LED lighting (18 gauge shielded for landing lights, 22 to strobes, both grounded back at panel with shield bonded to airframe at both ends).

You can always go up in wire size without jeopardizing the safety of the design. So you are good with 20 gauge. If you find yourself with high-density pins and 20-gauge wire you might find the wire is too thick to insert into the pin end. If so consider stripping the wire with the 22 or 24 die to cut out some of the copper strands so the wire will fit the crimp area of the pins/sockets. In such a case strip twice the length and use small heat shrink over the wire butted up against the pin to replace the extra stripped insulation to ensure if there are any intenerant cut copper strand ends at the base of the stripped area the heat shrink will capture those cut ends and encapsulate them to preclude shorting out on adjacent pin positions. The cut down area of conductor strands crimped inside the pin and small length under the heat shrink won't reduce the rated capacity of the wire to any meaningful degree.

The opposite is also true. If you have small wires like 24 gauge in standard-density pins or 26 gauge in high-density pins strip twice the needed length and fold the stripped area over on itself doubling the diameter so it fits the pin end properly. A prime example of this is the USB dongle wired into GDL 8X connectors used for initial programming with a laptop. Those signal wires are so small they wouldn't crimp into the base of the pins so the conductor strands have to be doubled to fill the pin cavity for the crimper to work. This concept also holds for full size ring terminals. If you run out of red terminals move up to blue and strip twice as long and fold over the wire strands on each other to make them thicker and keep on trucking while your replacement red ones are on order.

I am upgrading my RV 3 panel right now and employing similar techniques.

Jim
 
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