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Main CB Bus Feed out to a Fuse Block

LR60

Active Member
I am adding an 8 circuit Fuse block to cover miscellaneous circuits that I don't want on my main CB panel. (saving some CB spots for future upgrades)

What is best practice to feed power to this Fuse Block?

Should this feed wire be protected?

Should feed wire size for the Fuse Block be based on actual loads or should it be based on future higher current loads if Circuits are added.

Thanks in advance

Mark
 
IMHO, the feed wire should be sized to handle ALL the potential future loads (at same time) plus a buffer, and consider the available sizes of circuit breakers.

If the feed wire is longer than 6 inches, or passes through a bulkhead, I believe it should have circuit protection. The circuit breaker feeding this feed wire must be sized to protect the feed wire (ie not pass more current than the feed wire can an handle).

Don’t forget to include wire length (Probably not an issue in our size aircraft) and whether it will be buried in a bundle (probably not the best). Current ratings change if the wire cannot cool in free air.

Bevan
 
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CB?

If this is a main feed, with a large wire size, perhaps it would be better to use a fuse instead of a circuit breaker. The fuse is to protect the wire from melting, not to protect any equipment, so if it trips (blows) than something is seriously wrong and probably should not be reset.
 
It is not a good idea to have fuses in series. A hard short circuit can blow both the load
fuse and the main fuse or circuit breaker. I would keep the wire short (less than six inches)
between the main power bus and aux bus. Good workmanship will prevent short circuits.
 
I have a circuit breaker to feed my fuse block. The wire from the breaker to the fuse block is sized based on the circuit breaker. I did it this way to use a smaller wire to feed the fuse block and if necessary I can pull the breaker to turn off everything on the fuse block. I put non flight critical loads on the fuse block. Things like over head lights, usb aux outlets, Defog fans, etc.
 
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