Ground block part number

[sonex1678]

Another way to pull the new/additional wires through the wing is to solder the new wires to an existing one and pull them through as the old wire is removed--this is stronger than the tape method and also takes up less room in the conduit. As a last resort, the entire wire bundle can be removed (with a wire attached to aid in pulling the bundle back through), then the additional wires added, and the bundle pulled back through. The limiting factor to any of the methods is usually the conduit side and relative straightness of the conduit/bundle routing--the tighter the turns in the conduit/routing and smaller the conduit ID the harder it is to do. If new wires can't be pulled through the existing conduit/route, there may be a way to add the additional wires via another route--if this is done, it is best to ensure that the least protected/secured wires are grounds so any chaffing or subsequent shorting would be on the ground vice power side of the circuit.

[mfazio]

What size conduit are folks using? I'm thinking for a wing with light and strobes there would be 5 wires in the bundle. I believe wire size AWG 20 is the right size wire for LED lighting.

I have some ¾" OD soft tubing I was considering using and running it through the forward tooling hole. I'm concerned about chaffing so also considering grommets, in the end that is a pretty big hole in the forward rib.

Can anyone offer a better solution?

Mike


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[Sonex1243]

Mike;
I used 1/2" OD tubing from the "lowes" aviation department. I wouldn't go any bigger than that. Can't remember the brand, but, it was a milk white type that came in a 25' length.

[Bryan Cotton]

There is a good article that Bob Nuckolls wrote on the topic. You can find it here:
http://www.aeroelectric.com/articles/wiresize.pdf
Bob likes to keep his losses under 5%.

Also AC43.13 chapter 11 tells us acceptable voltage drops for aircraft. For a 14V system, they are ok with a half volt continuous or one volt intermittent.

My Whelen nav/strobe has 4 wires- nav power, strobe power, power ground, and synch. The strobes pull 5.2A when on, but only average 1A. The nav lights pull 0.48A. For the Waiex I estimate a 26' round trip for the wires. For 16ga wire, the drop to the strobes is 0.68V and the percent loss is 4.9%. This assumes the nav lights are on too, which makes for a bit of additional voltage drop on the shared ground. For 18ga the numbers become about 0.85V and 6%, which should be ok. For 20 ga it goes to 1.4V and 9.5% losses.

My landing lights are 0.68A and 22 ga is good with 0.4V/3%.

I plan to run 2 conductor 16 ga (2C/16) for the strobes. I will run 2C/22 or 20 for nav and synch. I had some 1/4" OD poly tube which fits nicely in the tooling holes, but this will be tight with 2C/16 and 2C/20 run together. I will likely upsize the aft holes for 3/8" OD tube. I will run my 1/4" poly in the front holes and 2C/20 or 22 for the landing light.

[Rynoth]

What size conduit are folks using?

I believe I used the same 1/2" OD tubing that Ken used. I just drilled up the fwd tooling holes to 1/2" and carefully slid it through the ribs 1 at a time (work slowly so you don't end up bending the ribs as you pull down the line.)



I won't be installing lights before first flight, but this was an easy step that would make future installation of lights far easier.

[Sonex1243]

I used 1/2" OD x 3/8" ID polyethylene tubing. Drilled the forward rib tooling holes to 1/2" with a unibit making a nice snug fit while threading it through the ribs like Ryan did.

I transitioned to the rear tooling hole at Rib #10 and #11 since the duck works light was installed between the two outboard ribs.



The AeroLED light wires are 3 conductor 20 gauge shielded and the duck works light wires are 18 gauge tefzel.

[DCASonex]

If using all LED lights and strobe, consider one multi-conductor shielded cable for all. 1/4" OD poly tube is a bit tight for this, 3/8" OD should work fine.

David A. Sonex TD #1327