Shielded wire

[Tblack]

Looking for 16-4 shielded wire but can only find UL listed speaker wire anyone have some suggestions.

[PapuaPilot]

Just curious what you plan to use it for? There is nothing on a Kitfox I can think of that needs anything like this.

Best practices for any airplanes is to use aircraft wiring, not automotive or other commercially available stuff. There is a big difference in quality.

Aircraft Spruce sells 16-2 shielded wire. If you really need 16 gauge buy two times the length and run 2 sets.

[Geek]

Looking for 16-4 shielded wire but can only find UL listed speaker wire anyone have some suggestions.

Agree with Phil that 16 gauge is kind of an 'in between' size for the Kitfox. BUT....... I would check with these guys.

https://skygeek.com/military-specification-m27500-16sb4t23-wire.html

The link will take you to a page that says it's 2 conductor but the part number is for 4 conductor. I have had this issue when using them. They have wire but the description is often in error. If you just order from the description and not the part number you can get the wrong wire.

Gary

[Tblack]

Just curious what you plan to use it for? There is nothing on a Kitfox I can think of that needs anything like this.

Best practices for any airplanes is to use aircraft wiring, not automotive or other commercially available stuff. There is a big difference in quality.

Aircraft Spruce sells 16-2 shielded wire. If you really need 16 gauge buy two times the length and run 2 sets.

Thanks for the reply, I’m installing AeroLed nav w/ strobes that have four wires. Per Aero these need a 10 amp breaker, looking at a ampacity chart 16 ga. is even light for that long of a run. Also installing Dynon glass avionics and they recommend using shielded wire to reduce feed back from pulsing loads. The magnetometer will be installed at the wing tip, nav/ strobe and magnetometer wiring will both run down the rear spar to the tip that’s why I was looking for 16/4, I had thought of running two 16/2 runs but while trying to find 16/4 I kept coming across the 16/4 speaker wire that is high quality wire and is also used in 12 volt systems. Like yourself I always want to use aircraft quality material, but many of the things used in experimental aircraft are not certified but are safe to use. That’s why I threw it out there to see if anyone had any information about non Mil spec. wire. Let me know if I’m missing something here.

[Benbell4140]

I spoke with tech support at aero LED a few weeks ago and he told me to use 20 gauge for the wing tip lights. He mentioned that larger wire would be needed for a longer run but the short run in a kitfox wouldn’t be any problem. I still haven’t ordered the wire yet.


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[PapuaPilot]

I spoke with tech support at aero LED a few weeks ago and he told me to use 20 gauge for the wing tip lights. He mentioned that larger wire would be needed for a longer run but the short run in a kitfox wouldn’t be any problem. I still haven’t ordered the wire yet.

That sounds good and it's right from the horse's mouth. :D

I am going to run the numbers again for my plane because I upgraded to AeroLed Pulsar NSP lights.

[Tblack]

Looking for 16-4 shielded wire but can only find UL listed speaker wire anyone have some suggestions.

I just measured our 7 and my run will be about 24' I was originally guessing that it would be close to 28'+. I plugged that into the calculator and we can get away with 18 Ga. accepting a 10% voltage drop. looks like 20Ga. would be a little small. That's just me being cautious. Attached is a screen shot of the calculator image.29631

[Benbell4140]

I just measured our 7 and my run will be about 24' I was originally guessing that it would be close to 28'+. I plugged that into the calculator and we can get away with 18 Ga. accepting a 10% voltage drop. looks like 20Ga. would be a little small. That's just me being cautious. Attached is a screen shot of the calculator image.29631

Thanks.. better to be a little on the big side than small.


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[PapuaPilot]

Only one problem, you are using the current for both strobe lights. There are separate wires going to the Lt. and Rt. strobes. The amps in each wire are going to be half of the total. If you run the calculator again using 4.9A you will find that you can use twice the length of wire previously calculated, and that 20 guage will work up to 27 feet.

[DesertFox4]

How about using our forum sponsor SteinAir for all your aircraft lighting, avionics and electrical wire and coax cable needs. They carry every size wire you will ever need in any experimental aircraft project. Service is great and likely Stein will be answering the phone when you call. Telephone: 651-460-6955 (tel:6514606955)

https://www.steinair.com/product-category/wire-coax/

[Tblack]

Only one problem, you are using the current for both strobe lights. There are separate wires going to the Lt. and Rt. strobes. The amps in each wire are going to be half of the total. If you run the calculator again using 4.9A you will find that you can use twice the length of wire previously calculated, and that 20 guage will work up to 27 feet.

We would agree if we wanted to put each light on it's own breaker, but the combined load at the breaker is still the peak draw of 9.9 Amps so a 10Amp breaker if we are powering them both on a single breaker. We don't feel comfortable putting a 10Amp breaker on a 20 Ga. conductor, if I'm thinking correctly the wire could overheat and
burn before the 10Amp breaker with trip.

[Tblack]

How about using our forum sponsor SteinAir for all your aircraft lighting, avionics and electrical wire and coax cable needs. They carry every size wire you will ever need in any experimental aircraft project. Service is great and likely Stein will be answering the phone when you call. Telephone: 651-460-6955 (tel:6514606955)

https://www.steinair.com/product-category/wire-coax/

Thank you for the lead, we will check with them.

[PapuaPilot]

We would agree if we wanted to put each light on it's own breaker, but the combined load at the breaker is still the peak draw of 9.9 Amps so a 10Amp breaker if we are powering them both on a single breaker. We don't feel comfortable putting a 10Amp breaker on a 20 Ga. conductor, if I'm thinking correctly the wire could overheat and
burn before the 10Amp breaker with trip.

Just trying to help. Your original question had to do with the gauge wire size, that's what I was answering. I will address CBs here too.

Using the stated 9.9A peak current means there are actually two 5A circuits going to the individual strobes. It is safe to use 20 gauge wiring, it can handle the 5A current for that length of wire per AC43-13.1B. Bottom line: You can save weight and readily obtain 20/4 shielded wiring.

But wait, there's more . . .
Regarding the CB: You are correct in not wanting to use a 10A breaker on 20 ga. wiring. If you choose to use 20 ga. wire you can use a 7.5A or smaller CB (see AC43.13-1B: Par. 11-51 and Table 11-3). Although the peak current is 9.9A for both strobes the AeroLed specs also show that the average current is 1.2A. This is what the CB is really feeling. A 5A CB would also work; it is both protecting the 20 ga. wiring, and provides 400% margin for the average current.

Still doubting?
I think the best way to explain the CB issue is to use an actual certified plane as an example. I maintain and train mechanics on the Daher/Quest Kodiak 100. Looking at the wiring diagrams I found the following. The Kodiak uses certified AeroLed NSP and SunBeacon strobes (apples to apples). They use a single 5A CB to feed two switches for the wing strobes (2 ea.) and flashing beacon. That means there are 3 strobes run through one 5A CB. The entire circuit uses 20 gauge wiring and the plane has a 45' wingspan (much longer wire runs then a Kitfox). The combined peak current for the 3 strobes is 11.5A, but the combined average current is only 1.4A. That is why they can use a 5A CB and 20 gauge wiring. Again, this is a FAA certified aircraft designed by aircraft engineers and approved by the FAA under the latest Part 23 certification standards.

Honestly, if you consider that one strobe circuit is only 0.6A you could safely use 22 ga. wiring. Actually the wire with most current is the ground because it grounds the nav and strobe; it would be 1.4A on that wire. Try running this number through the wire length calculator and see what length is acceptable.

Cheers!

[Tblack]

Phil,
Thank you for the great explanation, I wouldn’t have been concerned if the tech at aero yesterday hadn’t told me that we needed to use a 10A breaker. Using the Kodak for reference was a great idea. Aero doesn’t give a recommended breaker size in their data sheet that’s why I gave them a call. I’m all for using the lightest wire possible.
Regards

[PapuaPilot]

BTW welcome to the forum! I saw this was your first post on the forum and wanted to give you a proper answer.

Here is a copy of my wiring diagram for this circuit.


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https://teamkitfox.com/Forums/blob:https://teamkitfox.com/25a95a49-d9c5-4a85-a5c2-6392c9271ae9https://teamkitfox.com/Forums/blob:https://teamkitfox.com/63bf8d20-7f08-49e7-8e6f-705aa4501e4a

[Tblack]

Makes sense, used two breakers. Thanks for taking the time to post this.

[Delta Whisky]

Phil - a related, inquiring minds want to know, question (nothing to do with the nav/stobe light issue); specifically you said "It is safe to use 20 gauge wiring, it can handle the 5A current for that length of wire per AC43-13.1B." Why wouldn't you be able to use a 10A CB for two parallel circuits? (From your statement: "You are correct in not wanting to use a 10A breaker on 20 ga. wiring.") Thanks.

[PapuaPilot]

The problem is that a 10A CB is not protecting the wires, which a requirement in AC43.13-1B; it shows a 20 gauge wire must use a 7.5A CB (or smaller). If a circuit with a 20 ga. wire has a short and it doesn't blow the 10A breaker the wire can potentially overheating and cause a fire.

The circuit in the example I mentioned has 3 parallel circuits all on one 5A CB using 20 ga. wiring to all three strobes.

[Delta Whisky]

Thanks Phil - I appreciate your response. It did make me re-read the above postings and then get back into 43.13, and as painful as that can be, a good refresher.

I would add two points hoping that others might find helpful.

1. current calculation web sites often are for cars and assume a frame ground is being used. If return wires are used, the complete circuit length is to be used in the calculations/charts.
2. a small weight savings can be had when putting strobe, position, nav, and landing lights in wing tips by using a common ground but the total current in the ground wire has to be used when sizing.

BTW - there was a very good article in one of the aviation mags (either Kitplanes or Sport Aviation) only a month or two ago discussing ground returns; the considerations when torn between using wires or a chassis ground. (In full disclosure I'm a proponent of wires and a common ground buss.)

BTW (and this is an IMHO input) there are lots of automotive and marine wires that are as good as aviation wire for the intended use. They are supplied to one or more commercial specs which have to be read to determine usability in an aircraft. In all cases, wire used in an airplane has to be plated - raw copper like lots of the stuff off the selves in you see in the local BB store is no bueno. BUT (#1) - it is much easier buying to a milspec so this is a non-value added comment. But (#2) - if you are stuck between a rock and a hard spot . . . . . . . .

[Doggitz]

Phil

Nice drawing. What program did you use to generate the schematic?

Fred

[PapuaPilot]

Phil

Nice drawing. What program did you use to generate the schematic?

Fred
There are specific apps and CAD programs that can do wiring diagrams, but they have quite a big learning curve.

I just used Paintbrush on my Mac. All you really need to do are lines, text and basic shapes. I actually didn't take that long. It's easy to do colors too.

[DMMeix]

One of the easier programs for creating diagrams is Fritzing. It's geared towards PCB design, but easily applicable to what you're trying to do.

https://fritzing.org/learning/

[VictorV]

I've been using Skycad for my wiring diagrams. Here's a low-res snapshot of what it looks like. Fairly large learning curve but easy to make changes.

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