Required circuit breakers

[F1 Rocket]

I?m in the process of a total panel upgrade which has turned into an approximate 90% re-wire my entire airplane. I use to have circuit breakers for everything located on the panel itself. I don?t have room for this with my new equipment so I?ve decided to install a fuse box for the majority of the equipment There are a few circuit breakers I would still like to have easily accessible on the panel for which I still have engough space. My list for these is:

Master
Starter
Alt field
Autopilot
Trim

Are there any others I?ve missed?

Danny

[Hartstoc]

Originally Posted by F1 Rocket

I?m in the process of a total panel upgrade which has turned into an approximate 90% re-wire my entire airplane. I use to have circuit breakers for everything located on the panel itself. I don?t have room for this with my new equipment so I?ve decided to install a fuse box for the majority of the equipment There are a few circuit breakers I would still like to have easily accessible on the panel for which I still have engough space. My list for these is:

Master
Starter
Alt field
Autopilot
Trim

Are there any others I?ve missed?

Danny

I installed a breaker on the main feed to the fuse box(called ?Lighting? on my plane), but I guess it depends upon how far it is from the master contactor. Not sure you really need one for the starter if the starter solenoid is in series with the master contactor, it won?t help if your starter solenoid welds itself in contact. Also, depending upon how complex your avionics suite is, you might consider a fuse block dedicated to that, supplied through an ?Avionics? breaker. - Otis

[Mark33]

I'm doing the same thing with my -7 build. I'm using breakers with everything connected to the "essential bus" and automotive fuses with everything connected to the "main bus". I know that as a general rule you don't want to be re-setting breakers in flight, but I at least wanted to have access to items that I considered "essential" to flight available to me for either re-setting or disconnecting....(such as the alternator and autopilot).

[Mich48041]

If you have crowbar over-voltage protection, a circuit breaker is needed for the alternator field. A fuse can be use if there is no crowbar device installed. An alternator disconnect switch is needed.
The master contactor coil circuit does not need any protection at all because the negative wire is switched, not the positive. The contactor coil limits the current.
The starter contactor coil circuit can be protected with a fuse.
The autopilot can be controlled with a switch and protected with a fuse.

[dutchroll]

As a general rule through my aviation career circuit breakers have mostly been considered something to avoid resetting in flight, except in cases where they may be used to "power cycle" a piece of electronic equipment which has gone a bit astray in an attempt to kick some sense into it.

The only other time we ever really "planned" to tinker with circuit breakers in flight was by pulling them to remove power from items (for the remainder of the flight) which couldn't otherwise be easily isolated.

So....
1) Might you want to quickly isolate it from the electrical supply in an emergency? Consider a c/b.
2) Might you want to re-boot it if it plays up? Consider a c/b.
3) Would it be super handy for maintenance procedures? Consider a c/b.
4) Might you feel an intense need to re-set it if it pops? Have a think about your redundancy plans before you decide it needs a c/b.

For everything else, fuses would probably be fine.

my 2c worth....

[MCA]

Danny,

What is the "master" circuit breaker? The master switch brings the master contactor to ground and does not need a breaker.

[Larry DeCamp]

Functions that see surge overloads (not terminal or flight critical) are :
Alternator Field
Flaps

[F1 Rocket]

Thanks for the input. I ended up with Flaps, Alt, Trim, AP, and IBBS as circuit breakers on the panel. Everything else will be either fuses or circuit breakers on a remote panel. I know fuses will be lighter/simpler but I already have all of the breakers.

[petercavallo]

Put breakers in for things you might like to reset (or try to) ie really critical . mostly if a breaker blows something happened and reset wont fix it but some stuff you want to try
I would add Fuel pump

Flaps
Elec Ignition
Alt field

PS don?t forget your e bus