Switch/Breaker still bad idea?

[blueflyer]

I seem to recall a while back that the switches that also act as a circuit breaker were frowned upon due to them causing fires (I think).

Has that issue (whatever it was) been addressed and is it now safe to purchase these from aircraft spruce?

 

[SteinAir]

I think they are pretty much safe to buy from anywhere...the danger comes from the possibility of paying more!

Cheers,
Stein

 

[Canadian_JOY]

Breaker switches save panel space but generally cost more than the combined cost of a breaker and a switch. I've had to replace a lot of them in commercial service (helicopters) as they didn't seem to hold up over a high cycle count. I don't think this consideration would apply in most of our light aircraft as their switches won't see the same high cycle count environment.

There are two considerations that are germane to our light aircraft:
1) the bus wire feeding the "hot" side of the breaker switches is hot and un-fused - you'll want to carefully consider where you place breaker switches to keep the runs of unprotected wire to a minimum

2) in a field repair scenario where a switch goes "tango uniform" while you're out in the boonies, you can always jump across the switch terminals to produce an "always on" condition, and the breaker will still give you over-current protection. If you jump across the terminals of a breaker switch you will achieve that same "always on" condition but at the expense of no longer having over-current protection (solution - carry a spare in your on-board tool/parts kit)

 

[Walt]

In my experience, if you use Klixon and Honeywell switches you're more likely to get eatin by a shark than have a failure, I can count on one hand the number of failures I remember while in the airlines which use these same products (those airplanes are used more in a year than you will use your RV in 15-20 years)! On the other hand I've replaced a disproportionate number of the cheaper Tyco units and would not personally install them in my plane.

 

[blueflyer]

sounds like I may be good to go! thanks for the replies.

 

[DanBaier]

Not knowing any better - I built using the Tyco and so far ... all okay.

When I encounter difficulties, Ive made a note to self that I may have some general replacing to do. But, setting aside the brand name, I felt it does save a lot of panel space and time and would build that way again.

Dan

 

[airguy]

I used the Tyco for my breaker-switches, but I don't have them in high-critical or high-cycle applications. The common failure mode is the internal copper braid failing from repeated movement and breaking.

 

[Tom Martin]

I used a breaker switch for my EI, and it failed after 750 hours. This switch would have been cycled four times each flight. Once to start, once on runup, once as a live mag check at shutdown and then shutdown. Thus 4000 cycles.
The literature quoted a number less then that. When I took it apart the braided wire was broken. Visually the wire looked ok as with braided wire it is hard to see a break. During the prior year I had had some occasional rough running, very intermittent, and suspect that this switch was the cause.
It has been replaced with a standard breaker and a toggle switch.
I do not remember which brand of switch it was.