Replacing Fuses with Circuit Breakers

[spduffee]

I searched before asking, but couldn't find a specific answer: What is needed FAA-wise to replace fuses with circuit breakers? Can it be done on systems with a Generator? How time intensive is the replacement?
Thanks,

Shawn

[minton]

Log book entry with specifics related to matching the CB to the wire gauge.The club has a link to those numbers.

Yes you can use CB's for generator circuit but must be matched to the generator max output assuring that the wire gauge is correct.

Are you planning to or have you upgraded the wire itself? If not I would certainly get that old stuff changed out.

This project must include your A&P

[Bruce Fenstermacher]

Generator or alternator, makes no difference how the power is generated. the fuse/breaker is protecting the wire from overload. Replacing fuses with breakers is usually considered a minor alteration with a log entry.

If you had a single fuse holder in the panel by itself and you wanted to replace it with a single breaker, the job can be fairly easy. However that is not what you have in your '50 A model. You have a line of fuses mounted next to each other just under the switches they feed. There is a wire between each of these forming a bus. The other wire for the most part goes to the switch above it with a short wire. All the terminals at the fuse holders are soldered. There are screw terminals on the swithchs.

Separating one fuse holder and replacing it with a breaker can be a real hassle and a bit tedious. You must have a soldering iron big enough to get enough heat into to joint to unsolder it and then figure out how your going to reattach the previously soldered wire to the screw terminal on the breaker. Of course most of this while lying on your back with hot solder falling on you.

I would say the job is not for the beginner.

It is easier to replace all the breakers at one time in the'52 and earlier airplanes. But then this becomes a real project and the cost of the breakers adds up. And then when and where do you stop. There are old threads showing how I replaced the fuse holders with breakers in the same original spot.The easiest part is making up the two aluminum plates used to sandwich the original fuse bracket.

I thought you were selling the plane?

[bagarre]

If you do decide to replace your breakers, I'd recommend replacing them all as well as the wires.
It's really not that big of a job, but is tedious under the panel. If you replace everything 1 for 1, it's a log book entry.
If you add circuits or get creative, you'll need approval for the changes.
When I did mine, I went up one size on each wire. There's just not too many wires in these birds.

[spduffee]

Thanks all for the replies.
Yes, I am selling it, but I noticed the Landing Light fuse was bad and not knowing what kind of effort is behind it, I had to ask. Now I know, unfortunately. Bruce's reply was very vivid indeed. I think the first glob of solder to hit my face would send me off to the bad place in me. Seeing How these fuses are all but nonesistent, I will have to try one of the fixes discussed in another thread.
Thanks again!

Shawn

[spduffee]

Do you still have them? I thought you sent them to the other fella a while back. I'll take whatever you have, sure. Just send me a PM with the details. Thanks Aryana!

[KS170A]

I would say the job is not for the beginner.

It is easier to replace all the breakers at one time in the'52 and earlier airplanes. But then this becomes a real project and the cost of the breakers adds up. And then when and where do you stop.

I can vouch for this. I needed to replace a fuse...decided to upgrade to circuit breaker...decided to update all fuse holders to breakers...decided to replace all wiring...during which I found a cracked elevator bell crank...after which I found the horizontal bulkhead under the horizontal stabilizer had 5 cracks. Since I had the tail off, decided to inspect all flight control cables closely...ended up replacing all and their pulleys. Also decided since I had the panel apart, to clean up and update. One fuse cost me 18 months of down time (and I didn't keep track of exactly how much money)! That was doing all the work myself.

[Bruce Fenstermacher]

Dam fuses. So much trouble.

[GAHorn]

Gives an entirely new-meaning to the term "fusible link", heh?