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How many circuit breakers for RV-7A?

Guilhermepilot

Guilhermepilot

Well Known Member
I will start my panel and eletric system, evev togh my kit has not arrived yet I think I can get a alluminio panel cut and start work on that just to save time, system as follows
GARMIN G3X single unit with engine eis(all engine info here no gauges)
GARMIN VHF GTR 225
GARMIN GTX 327 TRANSPONDER
IPAD
AERA 500 PORTABLE GPS ATACHED TO PANEL
D1 DYNON POCKET EFIS ATCHADED TO PANNEL
AND 1 12V OUTLET
NAV LIGHTS
LANDING LIGHT

QUESTION IS how many CB,S do I need and wich amps?

thanks in advance
 
Breakers vs Fuses

IMO, first thing you or any builder should do with the electrical system is read Knuckolls's book which can be obtained here.

http://www.aeroelectric.com/Catalog/pub/pub.html

He is the guru many of us have used to wire our aircraft. After reading it you might toss the idea of circuit breakers. He recommends fuse blocks which are way lighter, way cheaper, take up much less panel space, etc...

Some like the looks of "acres of breakers", not me. Nomex on...

Just sayin'

Jerry
 
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I would agree with Jerry. Make a list of what each component draws and what the recommended breaker is per it's manual. Then think about what is flight critical and what would happen if multiple things go out. Also, the wire is sized for breaker size not load, so think about that too. Stein recommends a minimum size wire regardless of amps just due to environmental hazards like chafing and such. Some avionics have two power inputs each with a separate breaker. BTW - Don't let this list scare you for the apparent total amperages. That is a separate subject :)

SteinAir did my panel wiring and selected the breakers, but I had some idea of it before starting. What little I have sized and done to install, I conclude it pays to either become knowledgable and understand each element or enlist expert (singular) to make a complete wiring diagram including breakers. Look at the Garmin experimental website and my panel is pictured there. N266WL is on on the panel. There are several very good panels there to learn from.

I have several things that use automotive style blade fuses that are not flight critical, but can be reached easily once on the ground. Like heated seats, trim, baggage compartment light etc. I don't regret having my panel built, as it was bench tested and I know it works together.

Good luck with your panel planning. It is time well spent. Also, once completed, I wish I had though more about the physical placement of wiring runs and hardware. You may want to do this as it would have saved me a lot of time.
 
Vlad said:
On my RV9 I have nine breakers. Seriously. Guess how much you need on your 7 :)
Click to expand...

I have a few critical to flight. Ask yourself the question: If it trips in flight, do I really need to reset it?

All are pullable
Avionics master
flaps
Trim Switchable
Plasma ignition
alternator field
Auto Pilot
SD20 field
Two spares (I have no idea why)
 
I've never understood the obsession with needing to reset circuit breakers. A number of possible inflight emergencies don't faze me too much. But inflight fire does.

I prefer them especially for high demand items not so they can be reset, but because you can easily locate and pull them to isolate power to that entire circuit - something which I've had several colleagues on certified aircraft need to do when things have started producing smoke which wasn't called for!
 
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Sometimes you want to "pull" a breaker such as when doing maintenance/troubleshooting. You may want to pull the starter's breaker for safety when you have the main buss powered for testing/troubleshooting.

Bevan
 
I followed the advice of Bob Nuckolls and The AeroElectric Connection.

My -8 has one (1) 5-amp circuit breaker for the alternator field. The rest are automotive style fuses, with one big-a$$ in-line fuse on the big wire coming out of the alternator.

In 1000+ hours of operation, I had one circuit blow and that was the aforementioned 5-amp cb on the alternator field when the voltage regulator took a powder.
 
YellowPeril said:
I followed the advice of Bob Nuckolls and The AeroElectric Connection.

My -8 has one (1) 5-amp circuit breaker for the alternator field. The rest are automotive style fuses, with one big-a$$ in-line fuse on the big wire coming out of the alternator.

In 1000+ hours of operation, I had one circuit blow and that was the aforementioned 5-amp cb on the alternator field when the voltage regulator took a powder.
Click to expand...

I note that you have dual Lightspeed EI. I'm not sure about your particular model of LS EI but my understanding is that Klaus now incorporates inbuilt crowbar over-voltage devices to protect the units from a voltage surge. If you have a LS EI with an inbuilt over-voltage device I think you will find that Klaus wants you to have a CB for each unit rather than fuses. That gives you the ability in the event of a voltage surge to instantly reset one or both of the EIs and get your ignition going again (and perhaps your engine going again also ;)).

My recommendation is that you contact Klaus and give him your EI serial numbers so that he can advise you on this matter.
 
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I think I was one of the first to install a VP-50 so the answer is "1". The only CB I have is for the Lightspeed. I do have a fuse block in the subpanel for some things. I don't really understand the need to clog up an instrument panel with CBs anymore.
 
Captain Avgas said:
My recommendation is that you contact Klaus and give him your EI serial numbers so that he can advise you on this matter.
Click to expand...

Thanks for the tip. My units are 11+ years old, and I installed them as directed with fuses, but I'll drop Klaus a line.

They've been flawless, BTW.
 
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