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Wire Bundles

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skelrad

Well Known Member
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I'm nearing the end of my fuselage wire routing chaos, at least up to the firewall. Quick question re: coax - I've kept the coax as separated as is realistically possible in a small airframe. The bottle neck point is where it all comes together in the center tunnel under the fuel pump. Is it okay to bundle two or three coax lines together with the rest of the wire for this run through the tunnel and up the firewall, or do I need to pull the coax out and run it separately? Either way it's going to come together once it goes vertical at the firewall, so my assumption is the short runs together down the tunnel aren't a problem, but looking for more experienced eyes. It's still a work in progress, so yes, I know it's a mess.

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I have been looking for adhesive cable tie mounts that stick for 40 years. These work. If you want to remove them heating them with a heat gun works but they aren’t coming off otherwise. ACS has them. Send me a DM with your address and I’ll send you a few to try.
 

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Carl Froehlich said:
What you are doing is fine.

Note - if you want to use those zip tie anchors you need to remove the adhesive pad and epoxy them in.

Carl
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Yep, I pull the tape off, scuff them up and use GOOP adhesive. After a few days of curing, they are extremely solid. For this area, I'll probably grab some scrap foam from a shipment and put one or two strips above and below the fuel and brake lines just as belt/suspenders.
 
Mikeyb said:
I have been looking for adhesive cable tie mounts that stick for 40 years. These work. If you want to remove them heating them with a heat gun works but they aren’t coming off otherwise. ACS has them. Send me a DM with your address and I’ll send you a few to try.
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Appreciate it, but I'm good. Hopefully I'm done after I get this tunnel run finished!
 
Side note on this area - is it ok to drill a few holes in the vertical firewall stiffener so I can use Adel clamps for the vertical wire run? I can't find anything in the plans about that putting holes in the stiffener.
 
Seems like there's two shown on the 7(a) plans to secure two sections of the black corrugated conduit. They run from the tunnel up.
 
wirejock said:
Seems like there's two shown on the 7(a) plans to secure two sections of the black corrugated conduit. They run from the tunnel up.
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Thanks Larry. I finally found it on the OP drawings. I didn't get those OP drawings with my plans and didn't realize there was one related to wiring! It looks like they just show one adel clamp at the top. I'm guessing it's okay to put an additional hole at the bottom for a second clamp, but I'll follow up with Van's to be sure.
 
Brandon.
I installed the one adel clamp as shown in the drawing and to keep the corrugation centered on the stiffener glued one of the clamps that you have been using for wiring and then tie wrapped it on the lower end.
A

I can send you a pic tomorrow am.
 
skelrad said:
Thanks Larry. I finally found it on the OP drawings. I didn't get those OP drawings with my plans and didn't realize there was one related to wiring! It looks like they just show one adel clamp at the top. I'm guessing it's okay to put an additional hole at the bottom for a second clamp, but I'll follow up with Van's to be sure.
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Since the conduit enters the tunnel, I didn't see a need for additional at the bottom. I actually made the conduit run all the way to the center section. It's a bit more work to pull wire, but no big deal for a "wirejock". I also added a conduit either side going up the 9xx stiffener. Opposite side from the vent line. Same bolts used for adel clamps. They capture cables coming out each wing root so they don't have to snake all the way to the firewall and back to the panel. Save weight. You can maybe see one pilot side.
 

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I had tried the one by the original poster 5 years ago and they didn't work very well and took a lot of time. I ended up using https://a.co/d/eCEdcxY and they are all still holding strong after 5 years and lots of temperature cycles. If they do pop off they are easy to replaced or stick back on. The other things I have used this time around for wire bundles a lot more is the self healing silicone tape. https://a.co/d/e4CE99M I use it both firewall forward with the addition of adel clamps and firewall back. There is no adhesive, it handles temperature well, no chafing, and it can be removed and replaced easily to add a wire or change the bundle. Below is a spot I used a few of the plastic clamps to keep things tidy along with the silicone tape. The second photo is my avionics harness along with VPX power distribution. It can easily be removed from the aircraft in a few minutes. It connects via 2 cannon plugs. Third photo is how I lay out my wire bundle. Basically get the wire lengths laid down on the bench. Add each wire to the bundle one by one labeling each end as I do. Bundle it all together, strip and terminate. I just need to do the terminations and add the audio jacks for my homemade wh-00125 as shown in the third photo. Also gotta say, can't believe over 3 thousand hours of building before I finally bought a proper tape dispenser. Game changer, one handed operation and the time saved trying to find the end with your fingernail on a used roll pays for itself in a day!
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Drawing OP-26 shows a #10 hole drilled through the r/h angle in the vicinity of the firewall cutout thats intended to for the heater control cable to run through. If you weren't going to use that specific routing for that cable it would be a handy place for an adel clamp. No call to Vans required.

I did route the heater control pe that drawing, so I just wrapped the wire bundle in abrasion sleeve and wire tied it to the heater cable in that area. eeze-peezee.

I had another bundle running up the l/h side like you. On the left side rather than drilling a hole in the firewall angle I just glued a wire tie base on with shoe goo and wire tied that one as well. Like Larry, I didn't see a need for a clamp on the lower ends but I seem to recall that I used a wire tie base in that general vicinity as well. As long as you have good abrasion protection it's captured pretty securely by the heater cover where it comes out of the tunnel.
 
The only issue you might find is with the transponder coax. I would locate the transponder antenna ahead of the spar and route the coax separately from the other runs. There may not be an issue, but why take a chance?
 
penguin said:
The only issue you might find is with the transponder coax. I would locate the transponder antenna ahead of the spar and route the coax separately from the other runs. There may not be an issue, but why take a chance?
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Agree, don't bundle transmitter (xpdr/com) coax cable to a bundle of wires if at all possible.
 
flywithayres said:
Would multiple coax (4) run together through a dedicated conduit be ok? As in, one won’t interfere with the other?
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I would think so if you can gwt them to fit. The trick with coax is do you run the wire first and then put the ends on, or put the ends on first and fish them thru all the holes. I had a really good coax crimp tool so ran the coax first then put the ends on. This makes neat routing easier. Coax is a shielded wire so it doesn't bleed over to adjacent cables unless it is kinked or has another defect in the shielding, in my opinion.
 
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flywithayres said:
Would multiple coax (4) run together through a dedicated conduit be ok? As in, one won’t interfere with the other?
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The xpdr is the worst offender, high power pulsed RF so try to keep that one away from others as much as possible.
Keep the xpdr cable short as practical, power loss is quite high at 1Ghz
 
Thanks all for the sage advice. I’m planning to run the wire then do the connections for a cleaner installation. Also, I’m sure I can run a dedicated path for the xpdr.
 
Way back, I used to install all that stuff in police cars. Radios, computers, racks, light bars, oh my. What a chore. I'll give you one guess how many separate bundles were snaked under carpets and up pillars. That was long ago and coax wasn't RG400 double shield. No way I was going to run separate bundles. Thankfully, it wasn't a problem at UHF.

Fast forward to my airplane. All three RG400 coax runs take different routes. Just worked out that way. Runs are only as long as necessary plus a 6" service loop at the panel end.

Funny, a friend was chasing a horrible noise in his Com. He tried everthing. Coax, antenna, etc. I noticed my talkie had noise too. I looked up and noticed one of those spider looking LED lights. We shut off the light. Noise gone.

I always run wires then terminate. Easier to snake.
 
wirejock said:
Funny, a friend was chasing a horrible noise in his Com. He tried everthing. Coax, antenna, etc. I noticed my talkie had noise too. I looked up and noticed one of those spider looking LED lights. We shut off the light. Noise gone.
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Fluorescent lights can do the same thing. At least, the old ones did...actual fluorescent tubes. I haven't noticed anything with the newer tubes, but it could be a source. I was puzzled by noise in my system while assembling things in the garage until it hit me...turned off the lights, noise went away.
 
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