Wiring 101 - What Worked for Me
I found the various chapters of the Aero Connection a good primer on electrical theory - but the various Z diagrams were invaluable for designing my electrical system. I must have gone over Z13/8 in detail a hundred times - can't emphasize enough how valuable the diagrams coupled with the various notes were.
Some ideas (not inclusive) that worked for me (or that I wish I had done):
1) Build a wish list of electrical stuff you may want in your airplane - then figure out (spec values or estimates) the continuous load for each. It's continuous load that matters.
3) Figure out what you want for Plan B (backup alternator, if any) and Plan C (battery only) ops. Keep in mind some avionics components have their own backup batteries.
2) Pick an architecture - I don't think you can beat Bob's Z diagram options - again, I believe Z13/8 (or whatever the follow-on is) is the best for most applications. Determine what components you want on each bus. Your endurance bus is meant to safely get you on the ground in the event of main alternator issues - not continue business as usual flight.
3) Determine normal continuous load (plus desired wiggle room) to size your alternator. Bigger is not necessarily better.
4) Wire sizing recommendations are included in the Z diagrams. Keep in mind, electrons don't mind bigger wires - but tend to make smaller wires hot.
5) Figure out how you want to do the fat wires - I used welding cable, had the crimps done by the local Napa Auto Parts store.
6) Spend a lot of time figuring out wiring runs and where you'll drill holes through the spar (carefully) and firewall. Keep in mind the old rule that two pieces of matter can't occupy the same space at the same time - particularly around firewall penetrations.
7) Determine where you'll selectively use local grounds (strobes, wing lights, heated pitot for me) or the firewall-mounted multi-ground tab device (I used B&C).
8) Determine how you want to mark the wires (printed heat shrink or tabs - and do both ends) - also whether you want to use colored wires (I used too many white wires and regret it).
9) Practice crimping - use the best stripper and crimp tools you can afford. Realize coax is different. I used D-sub connectors whereever possible, but there are orher options. Also, practice soldering. Doesn't have to be pretty - just functional.
10) Document - Document - Document
11) Don't view the task as finishing your electrical system; view it only as doing your next wire as well as you can. Do wire continuity checks all the time. I didn't and the one wire that had a crimpp gap - even though it passed the visual and pull test - drove me nuts in troubleshooting.
10) Cut the wires longer than needed and design in service loops.
11) Be flexible - you will make mistakes and have better ideas as you progress.
12) DOCUMENT AS YOU GO - and pay attention to configuration management.
13) It gets a lot harder the more you close up the wing and fuselage skins. Carefully consider how you'll handle wing wiring - not much room to work the wires in the wing root after wings are attached. Do you really need disconnects or can you just cut wires if the wings have to be removed? I used connectors - and wish I hadn't.
14) Get professional help to wire the panel. I had Stark Avionics wire my avionics. Stein is a star.
15) Determine how you will build and secure wire bundles. I used both lace and cable ties. Bob's files give good lacing instructions.
16) I used fuze blocks mounted in my -8A's fwd baggage compartment. Figured the probability of a replacement fixing a blown fuze problem in flight was remote. Instead built backups into the comm (SL-30 and ICOM 200) and Nav systems (GPS and VOR). If I could do it again, I'd mount the fuze blocks on a fold-down door aft on the aft baggage compartment bulkhead.
17) Terminal blocks help a lot.
18) Stein and B&C were my suppliers of choice. You really do get what you pay for - so don't skimp.
19) You will need more - a lot more - electrical hardware components than you think.
20) I submitted specific questions to Bob via email. He always replied. I also attended his seminar (Auburn, CA, but he does them at various locations).
21) EAA has a very good electrical instruction series in their builder's library.
I had no wiring experience but found the electrical stuff was one of the more enjoyable aspects of building. After a couple glitchs (the connectivity issue described above and an ignition system short caused by insulation rubbing a hot engine component) the system has worked perfectly.
I also accumulated a lot of electrical documentation. Email me if want additional info.
[email protected]
CJ
