Some very basic questions

[Dorfie]

I am working on the wingtips, and while waiting for other things thought of running the electrical wires to the the tip through the conduit. I am planning on installing connectors at the wing root should the wings have to be removed in future. Good idea?
Planning on wingtip strobes, position lights, landing lights (poss 2 landing lights, Van's and duckworks LED's). I have 16 and 20 gauge wire at present.
1. What thickness wire will suffice for the different applications?
2. Have read about not to ground at wingtip. If I place a common ground on the last rib and ground all the wingtip lights to that ground, and from there run a single wire to ground in the fuselage common ground, will that be OK? What thickness wire should that be? (I assume this depends on the total current?) Should the wing be grounded to the fuselage as well?
3. Can all the wiring be done with the 16 and 20G wires? If not, what other gauge should I get?
Thanks.
Johan

[Bill.Peyton]

Johan,
Let me see if I can answer some of your questions for you.
1. Regarding using connectors at the wing attach points.... I personally did not use them. I don't plan on removing the wings after it is assembled, and if I do I will simply cut and re-solder splice them as required. I plan on using sealed solder splices for the power and A/P servo connections except of course the coax connectors. It is personal preference. Using connectors adds one more place to mis-wire, and unless you use mil spec connectors, plan on having intermittent connections sometime in the future.

2. Regarding wire size. You can download a wire table from ACS, Wicks, or EAA, but here are the specs in a nutshell

Up to (amps) Use wire size (AWG)
5A 20
10A 18
15A 14
Data signal 22

Your common ground must carry the total return current, so you need to add all of the devices current draw together. If you choose to run a common ground then do not also terminate the ground at the wing tip. That could create a ground loop, (dual current path) that may induce noise. You should always use a single point ground. You can choose to use the wing as a ground for such things as the nav lights, but for the landing lights, pitot heat, and A/P servos, I would run both power and ground.
Take a look at each device you are planning on locating in the wing tip to determine current draw and thus the wire size. If you are installing the Whelen strobes, they will come with a shielded power cable having it's own ground etc. Be sure to run a spare wire, just in case you add something later.
I would suggest that you order the Aerolectric book from ACS http://www.aircraftspruce.com/catalo...roelectric.php
It is a great reference and should answer most all questions you will have regarding your electrical system.

[Mike S]

I used a Dsub for the aileron servo wiring, and "glad hand" or "knife splice" connectors for everything else. Heat shrink over the glad hand units keeps them secure, and keeps out water.

[Bob Axsom]

I change wing tip configurations a few times each year going from tip tanks to no tip tanks, stock tips with lights to racing tips with no lights. I use knife splices for the wing to tank interface, direct terminations for the landing lights knife splices for the nav lights and the supplied connector for the strobe lights out in the stock cruise tip. I am concerned about the knife splice continuity over time with repeated connect/disconnect operations and I have squeezed a few of them already but I have experienced no trouble with them over 8 years of operation. I don't believe you have to add extra wires - with a little thought you can pull what you need with what is in there already. A single point ground is a good idea but practical implememtation is difficult. Some company standards allow no more than 4 terminals at one termination point and there are probable 40 or 50 ground terminals in an RV of normally equiped configuration. I have no ground at the wing tip. All of my ground wires terminate along the ledge on the bottom of the instrument panel and from there I run one heavy gauge wire with 60 amp capacity to the aircraft ground point on the firewall. I have no static or other electrical, communication or navigation problems.

Bob Axsom

[Rupester]

... Used by many RVers, is terminal strips located between seat ribs. I personally found that approach much easier than fiddling with multiple small crimped pins generally require for connectors. The ring terminals are larger and easier to manipulate than those iddy-biddy molex pins or similar. Yet they still allow removal and flexibility in the future.

[Bavafa]

Originally Posted by Bill.Peyton

Johan,
2. Regarding wire size. You can download a wire table from ACS, Wicks, or EAA, but here are the specs in a nutshell

Up to (amps) Use wire size (AWG)
5A 20
10A 18
15A 14
Data signal 22
.

Your wire size should also keep the length of the wire into account. The longer run, the thicker AWG.

[kentb]

I did, and wish that I hadn't.
You can't get your hands between the wing and the fuse once the wing is attached.
When I attached my wings I forgot and needed to remove it to get the connectors hooked up.
It just makes a lot more sense to use a little extra wire and do the connection under the seats. If you attach a connector on the wire, make sure that you can pass it though to fuse side.

Kent

[Buggsy2]

Originally Posted by Dorfie

I am planning on installing connectors at the wing root should the wings have to be removed in future. Good idea?

Yes but for another reason: this allows you to fully install the wiring in the fuse without the wings attached. If you want wire runs without breaks from wingtip into the fuse, you can't run the wing wiring into the fuse until the wings are attached. At that point you've probably built up the superstructure of the fuse (canopy and so on) and have installed the floorboards...so it's more trouble to install the remaining fuse wiring from the wings.

2. Have read about not to ground at wingtip.

I don't think this is necessary. In other words, go ahead and ground everything to the wingtip aluminum and don't run a return wire. The Dynon servo I'm using has its own return anyway.

3. Can all the wiring be done with the 16 and 20G wires? If not, what other gauge should I get?

Get some 24 gage wire in general, 20 gage is too big for a lot of work. Others have pointed you to the wire gage tables.

You might also want to post your question to the aero-electric list and ask Bob Nuckolls specifically to comment.

[Dorfie]

Thanks for all the replies. The questions keeps on coming though.
1. I've read about twisting the wires to prevent RF interference. Does that mean twisting the pair of positive and ground wires for each application? Can I just twist the whole bundle of wires going to the wingtip? How does this change if I have only one larger gauge ground wire returning to the fuselage from the wingtip? Is twisting needed at all?
2. Can you run two VOR receivers from one VOR antenna?
3. Is RG142 the correct/advised/preferred coax cable to use for VHF, VOR, glideslope, marker beacon and transponder?
4. Does the VOR antenna function as the localizer for ILS approaches? (I believe so). Do you need a separate antenna for glideslope? (I think so).
As you can see, electrics is not my strong point!!
I have ordered the electrical book from ACS....questions might get less!!
Thanks.
Johan

[Buggsy2]

Originally Posted by Dorfie

1. I've read about twisting the wires to prevent RF interference. Does that mean twisting the pair of positive and ground wires for each application?

You can do this but first, the dedicated ground wire is unneeded for almost all devices. Just think of the Al frame as your ground wire return...really large gage

Can I just twist the whole bundle of wires going to the wingtip?

No, not a good idea.

How does this change if I have only one larger gauge ground wire returning to the fuselage from the wingtip?

Then don't twist. But see my comment above.

Is twisting needed at all?

Occasionally and then the device maker will specify so or provide a twisted pair. For instance, the flap and trim motor wires, since they reverse polarity, are always in a pair, and the leads are twisted as supplied by the maker (at least the flap wires, can't remember the trim motors)...they must think there is enough current to make it advisable. So I twisted the pair of return wires too, back to the instrument panel. Otherwise there is no point.

BTW, you should refer to a proper reference to making a ground attach wire to an Al airframe. For instance, see AC43.13, Chapter 11, Table 11-14.