harness to harness service loops?

[alpinelakespilot2000]

I'm trying to keep my wiring as neat and as efficient as possible. Is there any rule of thumb for how much service loop there should be from one wire harness to another?

For example, wires from my intercom harness mate with wires from my Icom radio harness. I'm assuming I wire from the intercom d-sub connector to the icom molex connector directly (without any splices). There's really never any relative movement between the radio and intercom, so is there a need for any service loop? If so, how much of one would be standard?

Thanks.

[gmcjetpilot]

Originally Posted by alpinelakespilot2000

I'm trying to keep my wiring as neat and as efficient as possible. Is there any rule of thumb for how much service loop there should be from one wire harness to another?

For example, wires from my intercom harness mate with wires from my Icom radio harness. I'm assuming I wire from the intercom d-sub connector to the icom molex connector directly (without any splices). There's really never any relative movement between the radio and intercom, so is there a need for any service loop? If so, how much of one would be standard?

Thanks.

Good questions but hard to answer. In an attempt to answer a similar question I drew this out.



You can go crazy making service loops and disconnects and so on. Typically it has some positive affect but can also sometimes add complexity, weight, cost for little benefit. How often are you going to tear your panel apart. Avionics and instruments are fairly reliable. The idea I have, how to wire to make maintence easier:

Upgrade or swap out avionics
Work from the front of the panel
Reduce need to "panel dive" on my head
Trouble shoot and make logic and sense of the wiring

I guess you have a slider? My plan of attack is to make three sub panels, left (pilot), center (slightly off set to right), right (aux panel) and lower knee panels left and right for switches and CB's.

The idea? I hope I can pull individual components from the front of the panel with minimal panel diving to disconnect, OR remove the whole sub-panel and leave enough "service loop" so I can pull the panel out enough to work on or disconnect items or remove the whole sub-panel.

How? It takes some ingenuity and thought. I am working on that now and hope I am successful.

Again how many times am I going to tear my panel apart? Some guys are really talent and creative. Some have made tip down panels, which takes even more effort and creativity to route wires and tubes, allowing the panel to swing down. For me that is cool but a lot of work. However I'm sure they giggle happy in their comfortable seat as the fold the panel down and work on the guts with ease. One idea I had (stole) was slider rails so the sub-panels can slide out. The rails are like those roller ball bearing guides on high end furniture drawers.

At some point the idea is to go flying. Have fun.

PS: One thing, if you are going to be working on your head and panel diving, put longer items towards the top and shorter items lower in the panel. Short items on top will be hidden when working under the panel. Some items are rack mount some are not. Just make the wiring logical and label the heck out of it. Molex is fine but they do add more places to fail. However a few logical disconnects could be a nice feature.

[Bob Axsom]

As usual George provides a lot of good information and design forethought. Down at the basic level for individual wires I have one requirement that has stuck in my brain over the years. My first job after getting out of the Air Force was a "Radio & Electrical Inspector" on the F-101B and RF-101C for the McDonnell Aircraft Company in St. Louis. One of the inspection requirements was, every wire shall have sufficient length to cut off the termination and re-terminate it three times. In building my own RV-6A that requirement has been met or exceeded and I have no reservation about doubling wires back and tying them into the wire bundle/harness. Tying up the wire bundles/harnesses creates a new product visually that is independent of the individual wires and if you do that neatly the individual wire variations become obscure unless you have a short wire. Functionally you will not be able to tell the difference in an RV.

(Side note: My name is Axsom not Axom in spite of the member list , I loose my s enough in races as it is.)

Bob Axsom

[alpinelakespilot2000]

Thanks guys for trying to answer a question that was not very elegantly stated. The picture George provided suggests an answer to my question, as does Bob's three-termination potential. Common sense applies, as always--just leave enough slack for neat routing and future re-terminations.