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Initial wire order - how much?

Latech15

Well Known Member
The wiring is the most daunting part of this build for me. I am at the point of closing up the wings and I need to install some wiring for the zip tips, pitot heat, trim and roll a/p servo. I am going to just go with white wires and a heat shrink label maker. I know that I will need 16 and 20 ga for the zip tips, but I have no adea how much to order. I can't even see that stein or spruce just sell a roll.

Do you just order 500 feet of each and re order when you run out or is there som reference as to how much of each you will need?

Let's not make this a color coding argument. There is already a good thread on that, I'm just looking for a total footage of wire to order, for the first order.
 
Fortunately wire - compared to other aviation parts - is relatively inexpensive. Biggest problem is forgetting to install a run you’ll need later. So sit down, with pen and paper, and list everything electrical you can think of. Go to the airframe and think again. Don’t forget RG400 for radios. Then, for normal wires, measure the straight line distance, and double it. For coax, which costs more, lay in a piece of scrap wire (use tape) from each radio to the antenna location. Pull and measure the wire, add 20% more length. (Nothing worse than coming up a foot short on a coax run). Also use the ‘measure and add 20%’ method for expensive wire, like #2 for the starter. You’ll also need to figure wire sizes, based on current and length. You can find charts for this. One thing I did, to slightly simplify: I ordered no AWG16 wire. If that was the minimum size needed, I used 14. Very slightly heavier, but a bit simpler for planning/ordering. Bottom line, take as much time as needed to plan and get it right the first time. Yes, you can go back later and fix omissions, but it is awkward and time consuming. If you’re not sure, run extra wire now.
 
There are some runs that I want to get at least started before I completely close up the outboard bottom wing skin. I don’t want to do that after attachment.

I am sure a completely engineered plan would be best, I’m just trying to get an initial order in that will get my wing items, or at least the difficult ones taken care of.

I’ll just order 500’ of 20ga and 250’ each of red and black 16ga and start with that.
 
Vans kit

For a start, I bought the Vans RV basic wiring kit. It includes a range of wire sizes and connectors that are typically needed.
Then I added 100m rolls of Tefzel white 22 gau and 20 gau wire from rsonline.com, similar to digikey.com.
Additionally, I bought the Dynon servo harness/connector kits and brackets.
 
Before ordering wire, I made up a rough road map of harness routing and component location, and used that to rough out lengths of each run and work out estimated quantities. Then I padded each amount by 10-20% before making my order.

In the end, I still came up short on a few things and had to order a bit more. If I had it to do over again, I'd probably pad as much as 50%.
 
I started with the Van's wiring kit for my RV-6 build. It's a good value and covers most of the primary wire (not avionics). For that I used Dynon harness kits.

For wings you will want to think about strobe, position, landing, taxi, heated pitot, fuel level. Many people use shielded wire for strobe/position lights, I did.
 
Just like Philip says ... lay out your best plan on paper with approximate lengths and then add a goodly chunk. 50% would be plenty (he says grinning!) Then go on to estimate connectors! Good luck with that.

With your wiring, it's kinda like ordering fake stone to cover a fireplace or baseboard for a house. You'll end up with a lot of cut offs too short/small to use that just become waste.

I'm a big fan of having ALL your supplies on hand at the start to avoid any temptation to do something questionable! That includes tools as well.

Cheers
 
You should also account for the servo wiring too. My Dynon servo needs 8 wires and you have to plan where to connect the ends inside the fuselage. I ordered 1000' of 22 gauge for the avionic connection and I barely have any left. My plane isn't fully assembled yet.
 
Vans has a PDF file with a wiring plan for a loaded RV14. It lists all the likely wiring runs you could want. It has lengths on every wire. I built a fuselage harness per plan and it fit perfectly. For other models you could take that plan and use it to list the circuits and rough out what’s needed.
 
One other suggestion: Run a few spare wires (both single conductor and shielded twisted pair (22 awg), labeled so you can determine each end when you need to use them. Also, run a couple of "pull strings" in your conduits so you can pull in wires you forgot to run later. And yes, I ran a length of the Van's flexible conduit the length of each wing, and was glad I did. You can cut holes in this with a soldering iron (for rounded edges) to allow you to bring wires out of the conduit between the ends.

And leave extra wire length coiled up at the ends until you are ready to terminate each wire. It's a lot less painful to cut a few feet of extra wire off when terminating, than it is to find you are an inch short and have to replace the entire length of wire. (I recommend you do NOT splice a piece of wire onto and existing one to extend it. That creates an potential failure point, and can be a difficult failure to identify in the future.)
 
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