Why so many different circuit breakers?

[peter-h]

There are many very similar models e.g.

http://aircraftspruce.com/menus/el/circuitbreakers_klixon.html

I know why one chooses different types of fuses (fast, slow, antisurge, etc) but these CBs are mostly thermal and behave similarly.

Moreover, there are usually no recommendations on the equipment being installed on which CB should be used.

Here in the UK, most installers just pick any old CB of the correct style...

Is the large choice a historical thing, with most people using 1 or 2 models for all new installations?

 

[Areeda]

Sorry Peter. I had this and the joke thread opened.
Posted it here by mistake

 

[Let'sgoflying!]

the second post makes me think this thread might be some type of bait, but...

I am seeing many differences between the cbs shown; mounting method, rating, regular vs pullable vs dual function (switch & cb), form factor etc....
How about this, choose two and challenge us to find differences between them?

 

[gprellwitz]

the second post makes me think this thread might be some type of bait, but...

Nah, I think the poster just mis-posted here instead of the Friday Joke Thread. I'm expecting him to come delete this one. Which will, of course, make yours the second post in the thread!

 

[peter-h]

I probably didn't phrase it very well

There are a number of the 7274-type breakers and sure enough there are small differences in the specs, but what I don't get is what makes an avionics installer choose one versus the other, when there is no recommendation on most of the items being installed.

 

[denverpilot]

I am not an avionics tech, but I believe one of the reasons for such "variety" is that you must replace like for like on certificated aircraft or do a bunch'a paperwork for field approval/337 to change to a model that's not identical to the manufacturer's original. I'd love to retrofit our bird with pullable breakers, but I hear it'd be a hassle not worth going through.

That and for the experimental/homebuilt crowd, the things are relatively cheap and non-bulky for a place like Spruce to stock on shelves and they probably believe in the Marketing concept that having lots of variety makes you the big bad shop on the block.

 

[Capt. Geoffrey Thorpe]

That and for the experimental/homebuilt crowd, the things are relatively cheap and non-bulky for a place like Spruce to stock on shelves and they probably believe in the Marketing concept that having lots of variety makes you the big bad shop on the block.

I buy breakers from Mouser. Aircraft Spruce is overpriced.

 

[poadeleted20]

FWIW, when Lancaster Avionics redid my panel four years ago, they replaced (at my request) the OEM flush-type breakers with pull-able breakers (except the two alternator breakers which for whatever reason must be the flush-type). All documented and approved by the FSDO on a 337. Nice to work with folks who know what they're doing, including both technical and administrative issues.

 

[denverpilot]

I buy breakers from Mouser. Aircraft Spruce is overpriced.

Ahh... I should have known that you guys wouldn't be buying from "aircraft" places where the mark-up is instantly 50%!

Good ol' Mouser, and Arrow, and DigiKey... Dad worked in that electronics distributor "world" for most of my life, and retired from Bourns.

We certificated aircraft drivers get to bet our lives on the very best the 1970's had to offer! You guys get to use more modern stuff.

I feel so much safer knowing I can't pull my breakers but that they were "certified" for use in my airframe.

A 337, during a panel upgrade, is a great time to replace the silly non-pullable ones with something more intelligent. Its just that I doubt we'll be doing any panel upgrades of that magnitude any time soon.

In hind-sight as far as circuit breaker technology goes, the FAA requires special documentation to make the airplane safer.