Van's Air Force
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Wiring help
- Thread starter rwarre
- Start date
not recommended.
Most use a buss system to feed power to the electronics. It’s not impossible to combine “some” boxes but think about protection for the equipment. If you have 2 boxes that require 5amp protection and you splice them together- now you need a 10amp fuse. the 10 amp fuse is not protecting anything but the wire.
in a buss system you have individual fuses or circuit breakers that power and PROTECT each piece of expensive equipment.
Most use a buss system to feed power to the electronics. It’s not impossible to combine “some” boxes but think about protection for the equipment. If you have 2 boxes that require 5amp protection and you splice them together- now you need a 10amp fuse. the 10 amp fuse is not protecting anything but the wire.
in a buss system you have individual fuses or circuit breakers that power and PROTECT each piece of expensive equipment.
It depends. I use Dynon and all the avionic boxes use very low current. I use a terminal block similar in the picture. One side takes in the bus power from a fused or circuit breaker, and the other side provides electrical output to the rest of the support avionics. The only downside is if the bus power goes out, the rest of the avionic goes out too. Some people have a dedicated power wire to each of the unit. Simple saves weight at the cost of redundancy. More complicated means more weight, more wires, but gives you more granular control.
BTW, my Dynon manual lists the current draw to all the boxes so I could do the power loading estimate for the wiring design. So far during testing, the current draw from everything in the plane was only 8-9 amps. This surprises me too.
Attachments
Suggest you read Aeroelectric Connection by Bob Nuckolls as well as Aircraft Wiring Guide by Marc Ausman. Aircraft Wiring & Electrical Installation by Avotek Information Resources is also a good source. BTW, circuit breakers are intended to protect the wiring, not the electrical equipment attached to the wires
I recommend a separate fuse for each load. If a fuse blows, you won't have to guess which load is the problem. Fuse block(s) including fuses might cost less than one circuit breaker. And fuses are lighter weight and easier to replace than circuit breakers. Van's sells lighted fuses that glow when blown (provided that a load is connected). Never replace a fuse or reset a circuit breaker in flight. How often to you replace fuses in your road vehicle?
The simpler the electrical system, the better. Yes, there is an alternative to an avionics bus: Just one main power bus with all loads connected to it. If an avionics switch or relay in not installed, then it can not fail. Read what Bob Nuckolls has to say about avionics master switches. Avionics Master Switches: Really Necessary?
The simpler the electrical system, the better. Yes, there is an alternative to an avionics bus: Just one main power bus with all loads connected to it. If an avionics switch or relay in not installed, then it can not fail. Read what Bob Nuckolls has to say about avionics master switches. Avionics Master Switches: Really Necessary?
I 2nd this. Both points.
+1
My airplane uses only fuses in fuse blocks, none are accessible in flight. Main, Hot, Essential. (I do have backup batteries on things like EFIS, etc., in addition to the Essential buss).
No Avionics buss...not needed, and the stuff about "spikes" on starting is an OWT. Modern electronics can handle pretty much whatever is thrown at it, which is a *drop* in power on starting, not a spike, anyway.
And yes, get and read Nuckolls' book.
Fuses are fine for protection of the wire to each device, but with circuit breakers you gain the ability to pull the breaker to turn off the device (or devices) connected to it. There are a few of my devices that I want to be able to interrupt during flight, like the autopilot and AP servos.
I'm an old school Electronics Engineer (professionally registered EE), and have an individual circuit breaker for each load in my RV-10, with each breaker clearly labeled. I have been very happy with this arrangement, and have used it for trouble shooting before first flight, and testing back up functionality (e.g. what happens if the power is removed from on of my avionics devices. If the power goes out to my PFD, does the MFD revert to PFD function?, etc.)
But this is experimental aviation, so each of us makes a decision and builds our aircraft and avionics panel the way we believe best.
Cheers,
I'm an old school Electronics Engineer (professionally registered EE), and have an individual circuit breaker for each load in my RV-10, with each breaker clearly labeled. I have been very happy with this arrangement, and have used it for trouble shooting before first flight, and testing back up functionality (e.g. what happens if the power is removed from on of my avionics devices. If the power goes out to my PFD, does the MFD revert to PFD function?, etc.)
But this is experimental aviation, so each of us makes a decision and builds our aircraft and avionics panel the way we believe best.
Cheers,
A/P is integrated into the EFIS, so there's that. Servos have the A/P disconnect button on the stick (true, doesn't remove power from them, but they can be overcome by moderate stick forces anyway, like any well-designed A/P servo-aircraft system).
I use switches (and built-in power-off functions) to test things like what happens when a device is off-line or to, you know, turn things on and off, not CBs. But as you note, it's EAB...do whatever makes ya happy and comfortable in the air!
