What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

To conduit or not to conduit?

Paul K

Paul K

Well Known Member
Please help me out here. I am ready to wire the wings of my 7A and can't decide if I will install conduits or not. I have seen it done both ways, with good results. The question is, why would I want to install conduits or why wouldn't I want conduits. Beyond the obvious, will I really be changing or adding additional wires in the future? Would it be impossible without conduits? Is the added weight of the conduits worth the ease of future wire changes? Is it better for the wire to be in conduits? Wouldn't it be better to have the wires hanging in air and not rubbing on the inside of a conduit? The questions go on and on.

I would be very interested in what others have done and why. Help
 
Conduit it

Paul I vote for conduit. Easy to install, lightweight, cheap. Leave a string inside for your future wire runs.
 
I vote no conduit

I didn't use conduit and have no regrets. I've added a wire or two without incident. The only "challenge" is near the root with the closely-spaced ribs. Just tape the wire to a leftover piece of hinge pin and poke it through (make your holes in a straight line!). No reason you couldn't leave a piece of string there too for that matter, even without conduit. Bear in mind that future wire runs may not extend full span- say for an autopilot servo or heated pitot. Conduit wouldn't help you much in that situation. I assume it goes without saying that you DO need snap bushings in the holes.
 
Just getting to the conduit section myself and I vote conduit.

You don't know what you might add later. It's much easier to pull a string and not worry about fastening the wire down.
 
Conduit,

OK, so if I go the conduit way, what did all of you use? Did you get the stuff from Van's or did you go to the big box aircraft store? I would think that thin walled and very light would be best. I can also see leaving a small gap mid way through the wing for the pitot or auto pilot servo. Perhaps in the area of an access cover?

Any reason to worry about flame retardant materials away from the cabin?

Come on, there has to be a lot of opinions out there in Forum land!
 
Conduit, use the stuff Van's sells and then pro-seal it at each rib so it can't move and get cut.

Simple & light.
 
I used the black plastic irrigation pipe. Allows for some flexibility if you can't drill the holes in a straight line (like me). I put two in each wing - one that goes to the wingtip and a second that goes to the bellcrank bay (servo in L wing and camera in R wing).

greg
 
Depends on what you are doing. How much stuff are you putting in your wings? Are you a tinker? are you planning on upgrading?

I have simple wiring. Vans tip lights, LED nav & strobe. A/P servo. Dynon AOA pitot. So while I didn't need a lot of room, my 2/side snap bushing are full. No conduit for me.

Could I pull in more wiring?....probably. would it be tough?...definitely. Do I care?...NO
 
Paul K said:
OK, so if I go the conduit way, what did all of you use? ......Come on, there has to be a lot of opinions out there in Forum land!
Click to expand...
I would install conduit for no other reason than to have it available for potential use at some future date. Whether you choose to use it or not, Van's conduit weighs next to nothing. How much weight does it really add to the airplane? Well for my particular installation, I weighed it and that included all associated installation hardware. If per Van's suggestion you simply drilled a large hole through each wing rib to route the conduit through, the total weight would be even less. I posted the findings here:

http://www.vansairforce.com/community/showthread.php?t=14523
 
I used the Vans stuff and it took me about 30 seconds to pull all my wires in after the wings were on for good. I vote for conduit!
 
I would install the fat conduit that Van's sells for sure! I used the Home (and aircraft) Depot stuff and it is pretty light duty. Also, much smaller diameter. I completely underestimated how much wire was going to the left wing, so now I have the Van's conduit that I am going to replace the other with. The only problem is that my wings are closed up and the access is pretty terrible. I have to figure out how to enlarge the conduit holes. I can't wait for that project!

I also had to remove a baggage floor panel to run more wires to the tail. I vote for extra conduit everywhere. The stuff weighs nothing. I don't see how you could wire tie or panduit (zip tie) the wire runs in the inboard wing area properly with the limited access.

One thing though, the Van's conduit is NOT split like the Home depot stuff. Therefore, it will need weep holes drilled in it. (IMHO)
 
Home Depot

The stuff I got from HD isn't split and is very heavy duty.

Don't check the home electronics area of the store, go to the wiring/electrical section and search through their conduit. That's where you'll find the good stuff.
 
Go conduit

I am not building yet, but I recommend conduit. In my professional career I work on Navy avionics systems. I have seen too many cases of chaffed and cut wires that could be avoided with the simple application of conduit. Vibration in an aircraft is tremodous. Conduit will remove rubbing points.
 
On my quick built RV-9A I used Van's conduit. Pull it through half closed wings was tough. On RV-10 I brought 50' from Van' for $15 (it should come with finish kit too). It took only a few minutes to pull through each wing. I have plenty left for the fuselage. It makes running the wires easy and protects the wires from chaffing. It is also easy to poke a hole. For AP servo wires I cut a hole near the ballcrank and run the wires out through the hole. Since the tube is corrugated and the rib holes are drilled at the smaller diameter, the conduit stays put without further fastening. It is good solution for wire run.
 
Do it, MUCH better down the road. Get one thats pretty decent diameter, and put another that only runs as far as the aileron bellcrank in the right wing so if you add and autopilot later it will work well... As me how know :D
 
Do it!

OK OK You convinced me! I'll do conduit.

I ordered some of Van's and it should arrive later in the week or early next week. I appreciate everyone's opinions on both sides. I guess I just needed a kick in the tail to get going on it.

Thanks for your help. Isn't Doug's web site great! What would we do without it?
 
Last edited:
I have already pop-riveted my baggage and rear seat floor panels in place, not realizing that I may need extra conduit runs. The only cable holes I have are the ones suggested in the drawings. I would really like have the skyview in my panel, but don't see any way to run the cables to the rear in my current configuration. Any suggestions (other than drilling out a monster load of floor panel rivets)?
 
If I had to do it again, I'd locate the conduit nearer the middle of the wing ribs as others have done versus at the forward end. Being new to building, I did what I saw someone else do, but ended up with a joggle at the bellcrank bay to deal with. Not a horrible thing, but I'd rather have put it somewhere else.

http://www.aclog.com/rv-9a/images/Wing/DCP_1638.JPG
 
Smitty - I sent you an email, sorry, but I think you'll have to drill out one side of the bag floor.
 
PVC?

Am I right in thinkin that most of the conduit I see people using is made from PVC (aka milk jug plastic)? Also, take a peep at 43.13 for free air current versus conduit/bundle capacity. What's more, once you put a wire in a conduit, you can't inspect it. It does deter mice, but I've seen mice inside conduit. Hmmmm.
 
Smitty,

It's not that big of a deal to drill out the rivets and then replace them later. Also allows you to clean up the construction debris under the baggage and seat floors that has inevitably accumulated. Takes maybe an hour or two total to drill and rerivet. Yes, I've done this to add some wire conduit when I moved my battery from the FW to behind the baggage bulkhead.

greg
 
Thanks Greg!

I think I will do that. Also, I've noticed that there only 4 factory holes in the main wing spar to get wires through to the seats and baggage area. With all the cool dynon stuff to be added, there must be an issue with needing more cable holes. How did you handle needing more avenues to run cables around or through the main spar?
 
I drilled more holes, as small as reasonable. I think I ended up with one extra hole on each side and one right in the center, each about a half inch diameter (allows for a snap bushing and 3/8" wire - one of my wires is the #2 battery cable since I moved my battery to the back). I'm not a structural engineer, but what I know about stress/strain suggests that the best/safest place to put holes is in the middle of the spar web. If you're worried about it, I suggest a call to Vans (and would be interested to know what they say even though it's too late for me to make any changes).

cheers,
greg
 
This may sound nuts........

but, I used light weight 1/2" PVC. It is smooth and the wires can easily be pulled. I ran it through the lightening holes that have the pushrods. Anchored it down at the wing tip rib, ran under the bell crank brace and anchored it at the wing root. There is absolutely no way it can interfer with any controls or move. Did this on the advice of a seasoned builder and it works great.

Your results may vary.
 
You must log in or register to reply here.
Back
Top