I'm redesigning my Piper's electrical system after ripping out the panel completely. The only original thing remaining is the master switch and contactors. The new system will be a little more complicated with more devices.

I have a rudimentary understanding of aircraft DC electrical systems, and have taken into consideration the various installation documents that each of my new panel devices specify. I pored over each, looking for wiring diagrams, current requirements, and breaker size, if specified. Often the install docs will just direct you to AC43.13b for wire sizing, especially if the length of the run is variable.

But AC43.13b falls a little short in the design department. It seems to be written more to address specific ways things fail, more like a checklist of what not to do or how stout to make it.

Any recommendations on books or guides for electrical system design? Would also like some guidance on best practices for connectors and organization.

Thanks.

Hands down, grab a copy ob Bob Nuckolls’ Aeroelectric Connection.

It’s the Bible among the Vans RV crowd. He gives the book away free if you don’t mind downloading the chapters here. There used to be a link on his site for the whole pdf, but I can’t find it at the moment.

I think you can still buy a hard copy which may be easier to use in the shop, though whichever version you have includes many different electrical system schematics you can copy depending on what your needs are.

One of the best books anywhere on small aircraft electrical system design.

I had a friend that rewired his Fairchild 24 tell me to make a ground bus and ground it to the battery and airframe. I did that on the Canuck and it has worked perfectly.
I guess the same technique as wiring a composite airplane.
Dave

I took the EAA electrical course, it's a little basic, but I found it very helpful in giving me a solid foundation to work from. The Aircraft Wiring Guide from EAA was also helpful.

The other thing I would encourage you to do is find an online wiring diagram software and pull all your avionic's diagrams and make up a full system diagram. It'll really help you understand your system.

From the land down under, Australia's Civil Aviation Safety Authority has AC 21-99 - Aircraft Wiring and Bonding, online at

https://www.casa.gov.au/standard-page/ac-21-99-aircraft-wiring-and-bonding

The Aircraft Electronics Association https://aea.net/ offers classes as well as relevant publications (not free, but worthwhlie IMO).

In case you are unaware aircraft wiring and even the flow of electricity is different than any other application, so you need to proceed with caution. Let me share a few examples with you. These come from my experience rewiring my first C185.

First it's important to know that aircraft wire has a greater number of copper wires within the strand of a given wire gauge than say automotive wire.

Second, electricity flows on the outside of these strands, not in the strand itself. Except when it doesn't do that, and I have no idea why. Because of this, and the statement above, aircraft can use a smaller gauge wire than would be used in a car.

Third, when the CAA (now FAA) started inspecting wiring in aircraft builds, there was a nationwide shortage on dye so all the wires at the time were white. The CAA decided from then on aircraft wiring could only be white. Obviously there had to be some way to identify each wire so they devised a numbering system and each wire, no matter how small, must have its unique number stamped on it every so many inches. That includes if you replace a wire. So be sure and buy that tool.

Fourth, apparently electrons tend to get lost in aircraft. Perhaps it's the reduced oxygen at altitude. So it's important that you don't assume the electrons can get from one place to another without some assistance. This was demonstrated to me in my C185. The primary panel for all the instrumentation was made of a single sheet of steel as you'd expect. A ground wire from the negative side of the battery attached to this steel. Now in an automobile that would be sufficient. But not in the aviation world. Attached to that same connection was another wire that ran from there across the panel to the other end of this single piece of steel. Where it was attached to this piece of steel. The reason I suspect for this is to help electrons that are getting hypoxic, and because this situation the wire was actually black, not white. Apparently in an application such as this black wires matter.

Fifth, if you've ever tried to remove an instrument from the panel or the panel itself you've likely encountered wires that were too short to allow enough movement. Since you will be wiring your own plane you can help this by adding "service loops" in your wire run. Since space is limited, and in an effort to maintain some kind of order under the panel run your service loops around instruments, this way they remain neat and tidy. My 185 had a number of these.

Sixth, you probably already know that in aviation applications butt connectors, ring terminals, and other connectors are different than those used in the automotive world, so buy plenty before you start least you be tempted to run to the auto parts store to buy more if you run short.

Finally, zip ties are a no no in aviation wiring (no doubt because they are simple, efficient, and inexpensive). Instead you need to use those little things that resemble twist ties for like a bread bag. No idea what they are called or where you can get them but rest assured they will be harder to use, more annoying, and more costly than zip ties.

Hope this helps. Feel free to reach out to me anytime for more free advice.

Barnstormer wrote:..... if you've ever tried to remove an instrument from the panel or the panel itself you've likely encountered wires that were too short to allow enough movement. Since you will be wiring your own plane you can help this by adding "service loops" in your wire run. Since space is limited, and in an effort to maintain some kind of order under the panel run your service loops around instruments, this way they remain neat and tidy. ....

I knew there was a logical explanation.

hotrod180 wrote:

Barnstormer wrote:..... if you've ever tried to remove an instrument from the panel or the panel itself you've likely encountered wires that were too short to allow enough movement. Since you will be wiring your own plane you can help this by adding "service loops" in your wire run. Since space is limited, and in an effort to maintain some kind of order under the panel run your service loops around instruments, this way they remain neat and tidy. ....

I knew there was a logical explanation.

I have a salvage pacer in my hangar that has probably 1/2 mile worth of service loops. It has to weigh 75 lbs.

Don't forget that you have to allow for wire expansion under heavy loads also--
like an expansion loop in a steam line.