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Are switch/breakers worth considering?

Steve Ashby

Steve Ashby

Well Known Member
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OK campers, I don't want to get into the old circuit breaker vs. fuse block controversy. Let's just assume that, for whatever reason, I am considering wiring my plane with circuit breakers. What are the pros and cons of using the combination switch/breakers instead of separate switches and circuit breakers?
Thanks for your input.
 
I have switch breakers in mine but will probably redo the wiring to use an autos style fuse block later.

The breakers are not very flexible for growth. And the fact they are not all in the same place means you can't use a power bar. This worries me because I have a bunch of 10" - 24" wires with no short protection before the breaker. I know in theory when the wire gets hot the breaker trips but what happens if the short is before the breaker? It will trip but do nothing to prevent the wire from burning.

As far as usability I have no issues with them though.
 
I used the switched circuit breakers because it takes less panel space than a switch and a circuit breaker to control the same load. I think the switched circuit breakers have a rated mechanical life of 10,000 operations. Which seems comparable to a regular switch.
 
Just now finishing the panel wiring and...

this is my observation. I was driven to separate switch / CB implementation due to the small "standard" panel size in the -6A tip-up solution. This required a wire from the +Voltage Bus...to the CB...from the CB...to the switch...and then to the item being controlled. That is two wire segments, each with two crimp-on terminals.

If I had been able to implement the combo switch/CB, then I could have eliminated one wire segment and two crimp terminals from the circuit.

The combo switch/CB is physically larger (depth behind the panel area) than a "standard" switch. Also (from what I have observed), the combo device is only available as a two terminal device, so a double pole-double throw switch function would need to be implemented in a separate switch.
 
SCB

I used them in my 9A. As stated previously, they eliminate a wire or 2 per circuit therefore simplifying the entire system.

Steve
 
CB Switches

The Bonanza/Baron owners have had fits with them because of an FAA AD requiring replacement. The FAA position is that some of the switches have internal failures that produce overheating,etc.
Any Beech owners/operators care to comment?
 
S/B

My Baron has over 6000 hrs. with no problems with the switch breakers.
Now suddenly we have to change all 12 of them at about $100 a piece.
Can't even get them due to demand. I'll have some for sale cheep when I can get replacements.
But really, I prefer separate switch and breaker, they seem to operate smoother.
Bruce
 
I wired my 7 with CB switches to save panel space and wiring. They are all in a row and I used a copper bar to feed them all. Works for me. I have about 3000 hours in varous beech products (BE-18, 90, 200, 1900) with lots of CB switches and have only had one failure that I can remember. This CB switch certainly had over 7000 cycles on it. It failed in such a way that it would not turn on. I have had similar failures with plain old switches that are high time.
 
SkywayCaptain said:
I wired my 7 with CB switches to save panel space and wiring. They are all in a row and I used a copper bar to feed them all...
Click to expand...
This is exactly how I wired my -9 and they have worked well.



I have only had two problems with them. The first being a defective fuel pump switch/breaker that would not turn on when hot. By hot, I'm talking about baking under a close canopy on a 100 degree day. It was easy enough to change out, which solved the problem.

The second problem also applies to using any type of toggle switch. The switch/breakers are low on my panel and when getting in the plane with long pants on, you have be careful not to catch them on your pant leg. This would not cause me to change change the location as I'm very happy with my panel layout and switch/CB placement. However, if I had the cash, I would like to replace them with rocker switch/breakers.

Even when using automotive fuses, you will still find the need for some breakers. So if you go that route, you will need to plan for them.
 
fun with Beech Breakers

Vern said:
Any Beech owners/operators care to comment?
Click to expand...
Beech Skippers (all 200 of us) are also affected by the same AD. The Bonanza guys have done a great job disassembling and comparing the current and upgraded breakers (made by Tyco / P&B) and there is an internal failure where the switch shorts out in an unprotected way. There have been a very small number of overheated / burned up switches. There is a great document here for those interested:
http://bonanza.org/documents/2008.0821.CB%20AD%20update.pdf

BTW - I don't believe that Tyco is producing both the original switch and the upgraded switch. I suspect the "new production" switch that the Bonanza guys tested wasn't built to the new spec, but this is just a suspicion.

The problem is that FAA wrote the AD such that you have to use the parts from RAPID (Beech) and they are $120 each and unavailable. The only difference between a RAPID switch and a Tyco switch are the cool colored machined aluminum handle that Beech puts on.

In my plane prior to the AD I had allready replaced one switch with the new one (landing light) because it was getting "soft" in feel and was tripping too easy. That is a another, but safer failure mode.

Needless to say I'll be putting in regular switches and auto fuses in my RV. I'm not looking forward to spending $700 at my next annual on a handful of switches, all of which work now.
 
I bought one as...

..a test, and didn't like it.

It just didn't seem to have the correct "switch" feel to it when activated....

Try one out before committing.
 
Feel...

Gill,
Can you sorta describe the feel as compared toa regular toggle switch?

Bevan
 
Bevan said:
Gill,
Can you sorta describe the feel as compared toa regular toggle switch?

Bevan
Click to expand...


They feel a bit "squishy" in that there is resistance to a point and then they snap kinda like cocking a hammer on a pistol.
 
One other advantage to pullable brakers and switch breakers is that when working on the plane, you can drop power to a lot of your equipment when testing / working on other parts of your panel. This just came in handy today and is an advantage that I never thought of before.
 
I am about to finish the electrical part of my plane (apart from avionics). So, not flying yet.

I'm happy with my choice: all switch breakers for pilot side toggles (apart from battery/battery + alternator, which is a OFF-ON-ON switch and apart from alternator and starter breakers, which are just beside battery switch and are push/pull breakers) and all push pull breakers for copilot side.

I made four bus bars: main bus bar 1 (alternator PP [push/pull], starter PP, avionics SB, strobes SB, position SB, taxi SB, landing SB, fuel pump SB), main bus bar 2 (flaps PP, Pitot PP and the other PPs) (these are connected via a big #8 wire), avionics bus (another big wire #8) (all PPs) and ebus (all PPs). It is complicate, but finally it is not other than a segmented line of bus bars.

Switch breakers pros:
1) you save all connections between a push/pull breaker and a switch;
1-bis) you save panel space (I decided to put all toggles in the lower U channel bar, so switch breakers were the only answer);
2) maybe, you have all identical toggles.

Switch breakers cons:
1) they are not smooth as switches (i.e.: require more force to engage) (nothing terrible, anyway);
2) the last less, I read, than a "regular" push/pull breaker;
3) they only come in the OFF-ON flavour; so, if you want to have "strange" combination toggles, you will have to mix SBs with switches.

Camillo
 
IowaRV9Dreamer said:
snip>>>>
BTW - I don't believe that Tyco is producing both the original switch and the upgraded switch. I suspect the "new production" switch that the Bonanza guys tested wasn't built to the new spec, but this is just a suspicion.
Click to expand...

I noticed in the ABS document that both the new and old TYCO/P&B commercial switch/breakers have the same date code. Therefore, I'm not surprised that they have identical internal construction. I wouldn't be surprised if TYCO is phasing in the improved spring design the standard product as stock of the old springs is depleted. Anyone know an engineer at TYCO who can check the effectivity of the change?
 
Yeah...

N941WR said:
One other advantage to pullable brakers and switch breakers is that when working on the plane, you can drop power to a lot of your equipment when testing / working on other parts of your panel. This just came in handy today and is an advantage that I never thought of before.
Click to expand...

...but it's almost as easy to pull a fuse out for maintenance too...:)
 
Not a space shuttle

Although it is against the current popular movement, I did use c/b switches
where ever possible. The advantage, as mentioned before, of using one side
of the c/b switch as the bus (copper strap sold by Vans) and only one wire
outbound to the component (strobe, pitot heat etc) greatly simplifies wiring.
I also have only c/b's on the avionics bus (again using copper strap on one side of the c/b's as a bus) and components like the efis. My six had
c/b's and switches with only one switch failure in 800+ hours and 10 years.
On the -8a the switch panel is removable with service loops for easy maintenance if needed. IMHO simple is better.
 
Switch breakers

They work well and save space and weight. I have a mixture of all three. CB/Switch b/ Car fuse. I use a car fuse for each indiviual piece of avioncs that has one lead from a "Avionics" Switch breaker. I use CBs on my emergency bus. They all work. Design your system the way your want it.
Good Luck! Enjoy the "smoke" test
 
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