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Flush type circuit breakers

PostPosted:Sat May 12, 2018 8:07 am
by NDB_hold
On typical Piper (and many other) aircraft there are basically two types of circuit breaker: one type is flush when pushed in, and the other has a mushroom shaped head. The latter of course can easily be pulled or reset if required (or zip tied off), but is there a way to manually pull or reset the former?

Re: Flush type circuit breakers

PostPosted:Sat May 12, 2018 8:40 pm
by Trent772
You can't pull them, but you can reset them.

Big question is..... why would you :wink:

If it popped, usually it was for a good reason and you should look at it when on the ground.

Re: Flush type circuit breakers

PostPosted:Sun May 13, 2018 9:00 am
by NDB_hold
Because we had smoke from the wiring to the ventilation fan, and rather fancied isolating it rather than having to turn off the master. Luckily this was during taxy to parking after landing, although it did give us an exciting few minutes. Being able to pull a CB could have been vital in flight, though.

Not using the fan turned out to be a good solution...

Re: Flush type circuit breakers

PostPosted:Sun May 13, 2018 9:43 am
by PaulSS
That, to me, sounds suspiciously like the current value is too high on that CB. Seeing as they are there to protect the wiring, I would have expected the CB to have tripped some time before the wire started smoking.

I thought about buying those flush CBs because of their price but decided that I would want to be able to trip a CB manually. Sounds like a good decision for once :)

Re: Flush type circuit breakers

PostPosted:Sun May 13, 2018 10:12 am
by Trent772
NDB_hold wrote:Because we had smoke from the wiring to the ventilation fan



Sorry, I meant why would you want to reset, not pull :oops:

Re: Flush type circuit breakers

PostPosted:Sun May 13, 2018 2:11 pm
by NDB_hold
PaulSS wrote:That, to me, sounds suspiciously like the current value is too high on that CB. Seeing as they are there to protect the wiring, I would have expected the CB to have tripped some time before the wire started smoking.

I thought about buying those flush CBs because of their price but decided that I would want to be able to trip a CB manually. Sounds like a good decision for once :)


I think you are right - checking it we could see a much larger movement on the ammeter than was reasonable for turning on a ventilation fan yet the CB didn’t trip.