I had a 56', and even a broom like that!
A fuse as old as the average CB will fail, too. Both CBs and fuses are subject to oxidation, which creates resistance and causes heating that fools the device into opening the circuit. With a fuse, someone just puts a new one in and everything's fine because it's a new fuse, without any corrosion bewteen the tiny fuse strip and the end caps. Someone else resets a popped breaker, but the oxidized contacts are still there to cause further trouble.I have had circuit breakers fail intermittently or open at too low a current after popping but never a fuse. A fuse is all or nothing so I prefer a fuse for several reasons over a CB. And The FAA discourages resetting CBs without first correcting the underlying problem. Note that modern hi-tech cars use a lot more fuses than CBs. However, I have temporarily clipped a CB while troubleshooting the cause of the circuit overload.
A Both CBs and fuses are subject to oxidation,
I know that CBs may carry less current after opening several times since I have had this happen and can be an ordeal to replace but a fuse is extremely easy to replace and you get a brand new part for pennies. Also a lot cheaper, lighter and more compact.
A fuse can be a real pain when night flying. Fumbling with it in the dark and looking for the spare fuse right when you're trying to talk to ATC--or on an IMC approach--is not a good deal at all. I've found fuseholder caps under the floorboards; those tells a story all their own. Stuff like this is why airplanes got breakers.I know that CBs may carry less current after opening several times since I have had this happen and can be an ordeal to replace but a fuse is extremely easy to replace and you get a brand new part for pennies. Also a lot cheaper, lighter and more compact.
So tell me what the difference is between resetting a breaker and replacing the fuse. To the circuit it makes no difference at all.Are you aware that the FAA strongly opposes resetting a CB in the air for very good reasons?
As a mechanic I did not find that fuses were inherently more reliable. I found old fuses that didn't work and they hadn't blown. They were oxidized, and the fuseholder itself oxidizes in the cap and rear contact. I also found fuses of larger capacity installed in fuseholders because the right fuse wasn't available or it was impossible to read the rating in the dark while flying the airplane. THAT is dangerous, and you can't do that with a breaker.None. So do NOT do either so the in flight convenience of a CB reset is meaningless. But fuses are inherently more reliable. I have had an intermittent CB which I could never catch in the open state until one night when it finally stayed open. I never in 8000 flight hours had an intermittent fuse.
Not to mention a popped CB is obvious over a blown fuse plus the requirement to keep X-number of spare fuses on board to be legal. I don't miss fused airplane/helicopter electrical systems at all especially when trying to troubleshoot/isolate a problem or chasing a parasitic battery drain.Stuff like this is why airplanes got breakers.
https://www.faasafety.gov/files/notices/2009/Dec/SAIB_CE-10-11.pdf
In the above linked bulletin the FAA suggests that breakers be labeled "essential" and "non-essential". The essentials can be reset once in flight, but the non-essentials should not be reset.
This is why I use a CB temporarily clipped in while tracing the cause of the blown fuse. CBs are ideal on circuits with variable loads such as house wiring because you simply reduce the load and reset. If fixed load circuit fails it is highly probable that after resetting the CB it will quickly pop until you cure the underlying problem. My Cessna does not have CBs that can be pulled open and it is now recommended that all CBs be exercised annually because the are so subject to corrosion and other problems. My generator CB would fail and then work and then fail randomly until total failure (night flight) after about six months. It never popped. Of course it was then easy to diagnose. Fuses are unlikely to randomly reset/repair themselves.Not to mention a popped CB is obvious over a blown fuse plus the requirement to keep X-number of spare fuses on board to be legal. I don't miss fused airplane/helicopter electrical systems at all especially when trying to troubleshoot/isolate a problem or chasing a parasitic battery drain.
I guess for you fuses are good. But having worked on aircraft with over 75 fused circuits spread over 6 different fuse panels I prefer CBs. And in these cases is was more than a "few" spare fuses to meet the legal requirements. While CBs and fuses do the same thing, in my experience, CBs offer reduced upkeep and better reliability. As such I only use CBs when installing additional equipment or alterations. But I think you'll find it's more an industry trend toward CBs over fuses as there are a lot more STCs/alterations to replace fuses with CBs rather than the opposite. But hey, to each their own.But this is all so entertaining.
Neither. I prefer CBs based on 30+ years of maintaining helicopters and airplanes. And you?Do you prefer CBs because of scientific analysis or because it's what everybody else thinks?
No comparison. Aircraft are designed, whether old or new, to a completely different standard than cars or trucks. Perhaps give the design engineers at Bell, Boeing, Piper, or Cessna a call as to why there are not more fuses in newer aircraft? You might be surprised by their answers.Modern cars....
Why does it have to be endorsed by the FAA to be a good idea. Personally I think the FAA is rather incompetentAs a mechanic I did not find that fuses were inherently more reliable. I found old fuses that didn't work and they hadn't blown. They were oxidized, and the fuseholder itself oxidizes in the cap and rear contact. I also found fuses of larger capacity installed in fuseholders because the right fuse wasn't available or it was impossible to read the rating in the dark while flying the airplane. THAT is dangerous, and you can't do that with a breaker.
Breakers sometimes pop due to an intermittent overload (someone has added something to the airplane and instead of installing a separate breaker they just connect it to some existing breaker) or because the breaker is old and getting oxidation on its contacts that causes resistance and more heating than the bimetal actuation mechanism is designed for. If I was landing at night and the landing light breaker popped, I'd reset it after a short cooldown. If there really is a short somewhere it will pop again anyway. If I was on an IFR approach to minimums and the ILS breaker popped, you bet I'd reset it ASAP. One can get stupid about FAA recommendations and kill oneself.
Can you cite the FAA source that strongly opposes breaker resetting in flight?
Actually I feel the information given below is more relevant. He know electrical equipmentThe FAA is more concerned with in flight fires and feel that resetting keeps adding heat to a dangerous level on every reset. There was a recent small GA fatal accident due to this resetting starting a fire beyond the instrument panel and smoke filling the cockpit. Every pilot should be capable of flying with one electric device not functioning.
I would not be the least bit surprised by the the reasons why engineers at Bell, etc. use CBs. It's called following the herd. And I already knew what the majority of the responses would be on this forum. Why question what everybody "knows" to be true. But I question everything. Obviously I was not popular in church. (Glad Torquemada is dead.)
Thanks for the entertainment.
Yes, and as you have noted, modern encapsulated fuses do NOT oxidize but even modern circuit breakers that are not encapsulated (and they cannot be by design) will oxidize. When they break, and when they are reset, the miniature arc between the contact faces wears a new face over the oxide layer and then they are good for another cycle. Resetting the breaker is sort of like putting a new one in. If it KEEPS breaking, then we've got a problem. Single break, not a problem.
JIm