Silly Question time - all white wire?

Rgbeard

Rgbeard

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rgbeard
Get ready to point and laugh. I'm used to it.

Why do we use all white wires in aviation?

When you open up an automobile, or nearly anything else for that matter, wires are colored and the schematics have color charts/tables to help. Yet in aviation, we use this uniform white wire, making it difficult to tell one wire from another.

Red for +V, black for ground? Bueller?
 
Who said we do (use all white)?

I've seen multiple colors of wires often.

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As for why avionics shops don't, A) that's a lot of different color wires that you would have to keep in stock. B) the electrons don't care what color the wire is. C) Given the number of wires in a bundle, the number of different wire colors needed would be pretty large to be able to have a unique color for every wire. D) Being able to find a wire mid run isn't always very useful. If it was, you would probably see wires labeled every 18".
 
"We" don't. Historically many or most wire in airplanes has been white, but this is not as common now. Most power wires are red, most grounds are black and lighting/dimmer wires are often yellow or orange. However, many audio and communication wires are shielded bundles, which are usually white. The wires inside are white, white/blue, white/orange, white/green, etc depending on the number of wires in the shielded bundle. Most shielded wire is white. You may be able to get non-white, but I have never seen it unless maybe it has a colored stripe on the outside to differentiate one from another when grouped and routed together. A lot of old planes have numbers printed on the wires so you can find the wire on both ends of a run. The problem is that these labels get hard to read after 30+ years.
 
I guess my exposure has been limited to all-white-wire airplanes.

Every PA-28/PA-32 I've seen opened up was a mass of white.

Thanks. I'm glad to know it's not a 100% thing.
 
We use nothing but white exterior in the military world....Wires within a white jacket will be of different colors, based on what the wiring design guys selected. Typically, we also laser the wire information on each wire, about every foot or so. Harnesses get warp around or strip labels within a few inches of connectors or terminals. Single terminal wires typically get a piece of heat shrink with the wiring data on it, close to the terminal.

Easier to stock one color too. We buy wire by the tens of miles at a time....
 
If you look closely you will see a code printed on the wire for identifying each circuit.
 
There are only so many colors in the rainbow, and only so many color/stripe combinations. The OEMs elected to use white, labelled wires, and their schematics identify them that way. No fun, I know. BTDT.

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Rgbeard said:
Why do we use all white wires in aviation?
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FYI: To pick up on a point above, all aircraft wire originated from military specifications (MIL-SPEC) which only listed white for single conductor wire. The military being the largest customer, every wire mfg'r catered to that customer and only produced white. Fast forward to new technology and mfg processes the MIL-SPEC and other specs were updated to include different color insulation coatings. And as noted other rules and specs require a wire ID placed on every wire installed in an aircraft which is coded to which electrical system and item number in the print. So different colored wires are not really needed in general..
 
donjohnston said:
Who said we do (use all white)?

... Being able to find a wire mid run isn't always very useful. If it was, you would probably see wires labeled every 18".
Click to expand...

Actually, one really nice thing about the wiring harnesses in my DA40 is that every wire is labelled (laser marked) every 6 inches or so. I have done some avionics work on the airplane over the years and the combination of having comprehensive wiring diagrams and labelled wires makes modifications and servicing much easier and less error-prone.
 
NavAir said:
Actually, one really nice thing about the wiring harnesses in my DA40 is that every wire is labelled (laser marked) every 6 inches or so. I have done some avionics work on the airplane over the years and the combination of having comprehensive wiring diagrams and labelled wires makes modifications and servicing much easier and less error-prone.
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Before the laser marking it was ink-marked with a roller that the wire ran under. I was able to track wires that had been in the airplane for 40 years with that marking. I think some later methods included dot-matrix printing.
 
Labeling is the solution. Colored wires are nice, especially in personal home built but color blindness is an issue if color is used as a critical differentiator. Been there, done that.


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OEM wires in my Beech are white. But they are also labeled every 4 inches or so with the wire number indicated on the schematic.
 
NavAir said:
Actually, one really nice thing about the wiring harnesses in my DA40 is that every wire is labelled (laser marked) every 6 inches or so. I have done some avionics work on the airplane over the years and the combination of having comprehensive wiring diagrams and labelled wires makes modifications and servicing much easier and less error-prone.
Click to expand...
Never said it wasn't useful. I said it wasn't ALWAYS useful.

There were a couple times when I was making changes to my electrical system that it would have been nice to be able to identify a wire in the middle of a bundle halfway through it's run. But most times (~99%) having it labeled at the ends was more than sufficient.

I looked at getting my wires labeled. The cost convinced me otherwise.
 
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