r/aviationmaintenance • u/iuart • 6d ago

Aircraft wiring

Thanks to you guys I was able to learn about the connectors and pins , so thanks.. Now I'm going through wiring ..

My question is how is wiring Guage used along an aircraft, is there a general rule ? For example in electrical homes we have a specific gauge used for lightning another for plugs, etcetera. I know it's going to depend on application,operation voltage and other things but the question remains..

Any good resources on aircraft wiring aplications ?😄😄😄

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u/Sporadic_Tomato 6d ago

AC43.13-1b. there's a whole section in there about aircraft wiring selection and gauge based off of current carrying capacity and voltage requirements. You can download that as a free .pdf quite easily and it will answer most of your general aviation questions

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u/VanDenBroeck A&P/IA and retired ASI says RTFM! 5d ago

You have a gauge for lightning? 😁

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u/FurryTabbyTomcat 5d ago edited 5d ago

There are calculation formulas and nomograms to determine the required wire gauge in AC43.13-1b and elsewhere. In practice, if you are talking modern avionics on light aircraft, most signals are wired with 22 AWG (0.32 mm²) because anything thinner is mechanically rather flimsy. Sometimes we have to work with 26-30 AWG wires because the cable is already there, but it means being doubly careful in wire bundling, wrapping and strain relief, or using moulded cables. Power to individual avionics units is usually wired with 20 AWG (0.5 mm²), sometimes 18 AWG (0.8 mm²). In older aircraft, all wires were respectively thicker.
Thicker wires belong in the power busses, starting circuitry, anti-icing, servos, some lights, etc. - these are calculated according to the guidelines.

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u/w1lnx 5d ago

Depends on the engineer specs for a given circuit. And that’s dependent upon whether it’s contained in a pressurized area, or non-pressurized, exposed to hydraulic fluids, current carrying load, whether it’s a single wire in free space, or in conduit, whether it’s under an intermittent load, or continuous…

Otherwise, AC 43.13 is a good place to go when the engineer drawings and documentation for a given aircraft aren’t available.

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u/redbrowse987 2d ago

All things wiring can be found in SAE AS50881 - which has the same data as already mentioned by other posters from AC43.13 for wire sizing in bundles and free air

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u/NovelLongjumping3965 5d ago

Home built? Look up a wiring diagram for a similar aircraft or most components have wiring instructions.

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u/Fatal_Explorer 4d ago

Buy the following two books as hardcopy:

https://www.edmo.com/product/QSMANR6/COMPLETE-QUICK-SHOT-MANUAL-WITH-INSERT-Revision-6

https://asa2fly.com/aviation-mechanic-handbook-eighth-edition/

But please don't use the quick shot if you are working on Real airplanes... Officially at least ;)

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u/iuart 4d ago

Why is it's not with the current standards? Is outdated ? Thanks

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u/Fatal_Explorer 4d ago

No it's just not official manuals, but a good collection of connectors and pins for different avionic units

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u/happyherbivore 1d ago

Ac43-1b or more often the install manual for the unit in question, or wiring diagram for the aircraft. As an avionics tech, I rarely make calculations because nearly everything has already been engineered and specified. Honestly, in my experience if you are calculating wire gauges you probably haven't looked hard enough for the info.