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New wiring... What sizes?

NimpoCub

NimpoCub

Registered User
Nimpo Lake, BC . . . AKA "the Floatplane Capital o
I figger that while my Cub is nekkid, I might as well replace all the wiring too.

I've searched quite a bit but can't find the wire size (gage) to use on the various circuits. The old (original, I'd guess) wire has no discernable marks on it.

Here's my "clues":
strobes, starter, nav lights are all on 5 amp breakers
generator is on a 25 amp breaker
the 2 radios are on fuses, one is VHF, one is FM (both Icomm's)

How 'bout from the gen. to the main bus-bar & through the ammeter? (bus bar runs off a 30 amp fuse to the master sw.)

Can anyone say what size wire I should use for these circuits?

TJ gave me a hint the other day but not enough (for me) to go on. :)

Thanks (I hope)
 
The number one reason not to buy a used airplane -- rebuilt by someone who doesn't have the first clue what he is doing or how to do it.
 
Logan,
43.13 (I think that's the reference TJ gave you?) gives two criteria for wire size.

The first is current carrying capacity which is limited by heat buildup. The current carrying capacity depends on wire size, insulation type, and the number of wires in a bundle.

The second criterion is for voltage drop, which depends on wire size, current, and the length of the wire run INCLUDING the return ground wire, if used.

Select the larger of the wire sizes you get from evaluating the two criteria.
 
I agree that $300-400,000 will get you a great flying machine built by some fine people in Northern, MN. NimpoCub, It's not your fault the Packers lost.

Dave :wink:
 
Hi Nimpo,

I'm doing two Cubs in Vancouver, one Cdn registered one US registered. The wiring in the Cdn one will have to go back the way it was. The US registered will have the switches and circuit breakers relocated to the instrument panel with the appropriate 337. Both will have the battery relocated under the seat with the FA Dodge STC.

I'm in the process of setting up a table with wire descriptions, Ga, and length. I'm also doing a drawing to match. Then I will get them printed and cut to length by a really fancy and expensive machine. The thicker cables (starter) have printed heat shrink sleeves for the ends.

Now is a good time to do the www.plane-power.com STC's alternator conversion. This simplifies the wiring too.

A third set will be real easy (even with minor variations), so send me a pm (dhague@attglobal.net) if you are interested.

Don
 
WOW.

Thanks guys, ('cept that really smart/rich Packer fan) :) for the quick & informative replies. I got 2 websites with tables/info, and even a phone call to explain stuff. Incredible help. Someday I'll be smart/rich enough to give back here.

(I AM trying not to bug y'all) :)

This is such a rewarding/interesting learning experience. I made the decision with trepidation but I'm real glad I jumped in. My Cub will be far more MINE when I'm finished too.
 
Oh, Don,
Thanks for the offer, I heard about Inland comm (with that expensive machine) but I think I'll just put in white wires, and change to the alternator when I re-engine in a couple years. More than enough stuff to buy this winter for me!! :)

Thanks for the great offer.
 
Nimpo Cub wrote: "I AM trying not to bug y'all"



Hey, c'mon man; ask LOTSA stuff I can pretend to answer. I want to come pester you during fishing season, as soon as the 12 is in the air again!!
 
Geezer has the right stuff. The main idea with breakers is to size them to protect the WIRE not whatever is at the end of it - if you have a 50A breaker on 22 ga. wire you're going to have a fire because the breaker will never trip, even with a dead short. The manual that came with the radio (or whatever) will specify the load and then the length and size is determined by that. The longer the run, the larger the wire necessary. There are tables in 43.13 that list current and voltage drop, and when you need to increase to the next size.

This is one of those areas where you might want the assistance of a pro; you have to use the RIGHT SIZE wire for the calculated load (and length), the right KIND of wire, and then you have to route it and SECURE it properly. It is deadly serious stuff, even on the simple wiring found on a Cub. It's an airplane and HAS to be done right. Think about shorting a big starter or battery wire into a fuel line. Holy Flaming Moley.

Leave the fooling around to the fools.

I, for one, will sleep better knowing you're safe from THAT hazard!



:cheers
 
Nimpo,

There is a wiring diagram in the post-1974 little owner's handbook that might be helpful for you. The various wire sizes are labeled on each run.

I use tefzel M22759/16 wire. Also the 6ga wire listed from the battery to the starter didn't work out when I ran the numbers from the AC43.13 so I go larger.

This diagram is for an alternator which will be wired differently from your generator. The pre-1974 book has the generator wiring that you might use as a guide.

Vickie
 
Nimpo,

Here is a link to the diagram Vickie refers to.

There is one for the 1974 to 1977 models and another for 1978 and up.
There's a reference to Service Letter 828 on the former one.
Does anyone know what´s it about?

Sorry I don't have the generator version.

Vickie, would you say that AWG 4 was the correct size for starter cable,for modern starter/under seat battery location?
Vidir


http://www.supercub.org/photopost/showphoto.php?photo=18222&size=big&cat=500&ppuser=93

http://www.supercub.org/photopost/showphoto.php?photo=18223&cat=500&size=big&ppuser=93
 
Sir,

I believe the following websites may be of some assistance in accomplishing your project:

http://www.aeroelectric.com/

http://www.matronics.com/digest/dig...=html&Chapter=2008-01-23&Archive=AeroElectric

http://www.bandc.biz/index.html

http://www.vision.net.au/~apaterson/aviation/wire_types.htm

(Be advised this site is in Australia and may not constitute accurate advice re: wire / cable selection.)

http://www.steinair.com/store.htm

http://strobeguy.safeshopper.com/index.htm?248

http://www.whelen.com/aviation/index.htm

The book for sale on the AeroElectric Connection is an excellent source of information -- it's oriented towards the experimental community, but the info is exceptionally pertinent for all aircraft.
 
Now THERE'S the info I need. I plan to go at least one size larger to be on the safe side anyway.

I did find some #'s on the old wire but they didn't make sense, I suspect they were some kind of assembly #'s for the different harnesses.

Thanks again all, for answering a tough question. I have enough info to see what WAS installed and enough sense to install a titch larger for safety. The last thing I need on a fun flight is acrid smoke & things shutting down!! :)

I'll sleep well tonight (& go snowmobiling again tomorrow).
 
The number two reason why not to buy a used cub -- rebuilt by someone who adds weight "for added safety" without any engineering basis.
 
STMAWR14 said:
adds mass quantities of unnecessary weight
Click to expand...

If your posts had anything but negativity they might have some credibility.
A titch of intelligence always helps too.

Stay in your own bitter/negative world & leave us (me) alone.
 
I had several questions I was gonna ask about my 12 but I guess I`ll figure it out on my own my wife hurts me feelings enough without any help from STMAWR14
 
Wag-Aero has a basic wiring diagram for the 2+2 and the sport cub that is a real good start to make your system. I'm lucky I have a friend that builds homebuilts that happen to be an electrical engineer,
 
12 Geezer said:
Fer cryin out loud, STMAWR14, how about tending to your own knitting!
Click to expand...

Sounds like cabin fever, Fresh air and a couple of hours of flying will cure......plus reducing the intake of coffee, too much caffeine causes moodiness. :angel: :morning: :morning: :morning: :morning:
 
Logan, Could you figure out the wire size chart in the AC43.13? I wouldn't up size everything. It was designed and regulated by people who knew what they were doing and has been proven by the test of time. Someone else commented on the circuit breaker being sized for the wire not the device. If you up sized the wire you will need to up size the circuit breaker. Never had a problem with wire size on Super Cub wiring except with starters and a lot of that was caused by corrosion and aluminum wiring.
 
Steve wrote: "If you up sized the wire you will need to up size the circuit breaker"

I wouldn't agree with that, Steve. The wire would still be protected by the too-small breaker, and the breaker would still be properly sized for the designated load.

I do agree though, that oversizing wires without a sound engineering reason is a waste of money and weight.
 
I agree but the circuit breaker is designed to protect the wire. I guess it gets into a chicken and egg kinda thing. :lol: Good reason to stick with tried and true. :wink:
 
You can make the wire bigger and bigger and bigger Steve and it will still trip the breaker at the, say, 15 amp rating of the breaker and never hurt the wire. Now if you go smaller and smaller on the wire and still leave the same 15 amp breaker on it...then the wire could overheat and release the "magic smoke" before tripping the breaker.

And we all know why it's called magic smoke right...or does STMAWR14 need to 'splain that one for us too?
 
Maybe we're buying into an oversimplification, that the circuit breaker is to protect the wire. Is the presumption that whatever device is powered by the circuit, is internally protected form overcurrent? Certainly that wouldn't always be the case, lighting for example. So the breaker protects the entire circuit. For sure, though - using the tables, which are thoroughly tested, makes nothing but good sense.

I'm just having some fun nit-picking, Steve - been up for 38 hours straight, completing a so-called "professional certification" process that is mandatory for Washington state teachers. And as an aside (insofar as bureaucrats are concerned), teaching in my 'spare' time. My finished product is over 400 pages that nobody will EVER want to read, and I'm feeling just a bit testy!!!!!!!!!!! Ok, a LOT testy - - - What if I'd spent all that time making great lessons for my students, like circuit protection experiments - - instead of writing all that bureaucratic, politically correct bs.

Ok, I'll shut up. It's just that most of my life I've had dirty fingernails - that actually benefited from the book learning of engineering school - - - this education pablum we have to focus on, rather than just teaching the kids, is something else!

Ok, I'm on a sleep-deprived, caffiene and wine enhanced roll here, so a quick story. Today I put my 400+ page 'portfolio' on my principal's desk, together with the forms he's supposed to sign indicating my work is satisfactory to him, before forwarding everything to the big shots at the university and the state. He glanced at the binder, and then at me, and said - "with that, you are no doubt a MUCH better teacher now." Then he looked at the forms again, then at my binder again. And just sat there for a moment. Tapped the binder with a forefinger and said, "That is an EXCELLENT document". Never lifted the cover before promptly signing the forms as 'accepted'. The key, I think, is that his hair is the same color as mine but didn't used to be - - -- Needless to say, he's a great boss.

Ok, I WILL shut up now.

Just use the tables, Logan - you'll be fine.
 
Steve Pierce said:
I wouldn't up size everything. It was designed and regulated by people who knew what they were doing and has been proven by the test of time. Someone else commented on the circuit breaker being sized for the wire not the device. If you up sized the wire you will need to up size the circuit breaker.
Click to expand...

Thanks Steve, but
I just want to upsize the generator output & the two for the master switch circuits. Those are the ones I wanna make sure don't get warm (they have the potential). And they WON'T be routed anywhere near the (new) fuel lines. The couple tiny wires that I'll replace with 16 is just so I don't have to buy several sizes of wire. Maybe I sounded dumber because I wasn't too clear.

The weight difference will be about as significant as what I happen to have in my pockets at flight time. (IE: not) If my tail light shorts out it will trip the breaker even if I use 6ga wire if it's on a 5 amp breaker. Also, I'm not planning on coming to Valdez to terrorize you guys so my Xtra weight isn't a concern to me.

Owner maint. planes are not saleable into the U.S. so ol' what's-his-name need not be concerned either. :)
 
12 Geezer said:
Just use the tables, Logan - you'll be fine.
Click to expand...

I think so too. I'll sleep well.

Don'tcha just love a wise ol' geezer??
 
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