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Why do most professional panels use circuit breakers?

Not building anything yet. Still dreaming.

I've read lots of information from http://www.aeroelectric.com/, and tend to like those designes. Keep things simple, use fuses instead of circuit breakers, etc. All of that makes sense. Some builders follow those ideas, some do not.

But the thing that strikes me, is that nearly all the photos that I've seen of professionally built panels devote a huge chunk of real estate to circuit breakers. Why? Is it just so that they look like a certified panel? Is there something wrong with the electrical system designs on http://www.aeroelectric.com/ that I should know about?
 
I built my panel and used about 25+ circuit breakers to protect all the electrical devices. I would prefer to just push the breaker in to reset the circuit as opposed to trying to find the correct fuse and replace it while in flight. Other opinions may differ.

Fuses and holders also take up real estate and, if remotely located, will be a real pain to replace in flight. Your plane, your choice.

Roberta
 
Yes, but what about electrical fire safety?

Fuses and holders also take up real estate and, if remotely located, will be a real pain to replace in flight.

True, but the way I understand the idea is that one should not be playing mechanic while flying anyway. If a circuit got overloaded, should you really be resetting it in flight? Isn't it better to get on the ground first? If the circuit breakers or fuses are properly sized for the wires, and they get overloaded, resetting a breaker or replacing a fuse makes for the potential for an electrical fire. If there are nuisance trips because there is too much load on a particular circuit, then something needs to be redesigned behind the panel anyway.

Your plane, your choice.

Yes, I'm just trying to understand the issue better so that I can make the right choice someday.
 
snip . . .. But am curious why most professional panel builders are choosing to use circuit breakers.

It looks cool and cost way more money.

I used breakers for everything essential to flight (fuel pump, EI, Avionics master, flaps, alt field(although I decided I would never use it in flight), auto pilot, switched breaker for trim (Pilot side for trim cutoff)).

Everything else, fused. My logic either I can fly without it, or example, if my 430W popped a breaker, I am going to have it checked out before I power it back up. Altogether, 22 fuses and 8 breakers. I know, I am over protected. But. as Roberta said " Your plane, your choice."

I think I am about to get fined by the thread police.
 
I used both. Breakers for items I might want to isolate or reset, and fuses to protect items I probably wouldn't reset in flight anyway.

L.Adamson -- RV6A
 
I think the answer to your question is that most professionals use breakers cuz most professionals use breakers. It's the same reason your doctor prescribes the exact same meds as the next doc. Pros know that the best way to stay out of legal trouble is to go with conventional wisdom.
 
Being that I've just about finished all the wiring to my fuse block I'll give you my perspective. A fuse block is bulky and for me it almost impossible to locate in a reasonable location. Once located however I felt it was a winner location and now that it is mostly wired I still think it's a winner. However, circuit breakers have the advantage of compactness. Push to reset type breakers can be placed in just about any open real estate on the panel with just a little planning for wire routing. Combo switch/circuit breakers are the best of both worlds from what I can see, although expensive. My biggest reason and almost the only reason for not going the circuit breaker route was that I couldn't find a way around having a rather exposed hot buss somewhere inside the cabin. Fuse blocks serve as that buss with the main power going directly to the block first and of course the block is manufactured as a well insulated item. A reason for certified builders to choose breakers may be that the buying public has certain expectations.
 
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IMHO

Acres of breakers used to be universally "cool". In the modern era, simple is sheik for modern designs in my opinion. I used 6 breakers on those loads that I might want to reset / or disable in flight; A/P, Flaps, Endurance bus, Aux Power receptical, Pitot Heat, Pitch Trim. The balance are (many) fuses in the rear of the glove box. Theoretically accessible in flight, but I have a fault tolerant system that won't require such gymnastics.

In my humble opinion (that is for MY RV), my only need for an acres of breakers design would be to reproduce the aesthetics of a "period piece". That is, to give a plane that retro "fighter" look. Were I building an 8 or an F1 with a fighter paint scheme, I would probably do so myself.
 
Why do most professional panels use circuit breakers? Because its better

Not building anything yet. Still dreaming.

I've read lots of information from http://www.aeroelectric.com/, and tend to like those designers. Keep things simple, use fuses instead of circuit breakers, etc. All of that makes sense. Some builders follow those ideas, some do not.

But the thing that strikes me, is that nearly all the photos that I've seen of professionally built panels devote a huge chunk of real estate to circuit breakers. Why? Is it just so that they look like a certified panel? Is there something wrong with the electrical system designs on http://www.aeroelectric.com/ that I should know about?

Bob N. is a big fan of fuses. And if you disagree with him you are worse than Attila the Hun. :D

Seriously use what you want on a home built. The beat the horse to death subject has been covered in previous threads, but those threads do have excellent points (not mine :rolleyes:) but points on both sides pro and con. Read them and do as you feel makes you warm and fuzzy; than don't look back.

I like fuse for less panel space, low cost and no doubt lighter weight. Of course you have to almost accept any trip in flight will have to wait, which is fine if you understand that. I would like to see the ATC fuses in the panel, where you can get at it easily. One of vans planes has a handfull of fuses visable in the instrument panel. With a simple plastic tool replacement is a snap.

I like CB and that is what I have, about 18 of them. I like the ability to pull power from a circuit, low use switch, see a trip and reset it with out fishing out a fuse and finding another to stuff back in. Bob N. will discount all that and says you don't need that.

Other there is equal safety when it comes to the reason for them, protect wires from getting red smoking hot.

However some who sing the FUSE only mantra like Bob N use CB's for some of their most critical circuits? :rolleyes: There is a long story and excuse to go along with that inconsistent policy, but oh well........ I guess than if you could only use one, fuse or CB, than FUSES alone are not good enough for all uses but CB's are.

Cars still use fuses and they seem to work OK. Most Airliners have a sea of CB's and they work.

Cheers
 
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But the thing that strikes me, is that nearly all the photos that I've seen of professionally built panels devote a huge chunk of real estate to circuit breakers. Why?

Because that is the way they have always done it.

If you do things the way they always have been, you will all be what you have been.
 
Almost all of the abnormal/emergency procedures in the checklist of the Bombardier I fly have you set, pull, or pull/reset at least one breaker.
 
Doesn't seem to me to be a big deal either way. I prefer CBs because they do multiple jobs (kinda like Alton Brown's 'no single-taskers in the kitchen' philosophy). A CB simultaneously acts like a fuse to protect the wiring, acts like a switch to let you isolate an electrical problem, gives you a chance to try again in the event of a momentary overload, and gives you a visual indication of where the problem is. Still, you could do all that with fuses, switches, and status lights. However, for coolness factor I'm surprised that no one has come up with an ICB that lets you have a programmable array of circuit protection, complete with load monitoring, reset ability, and a little LCD status/programming display. The only problem I see with such a device is you'd want it to failsafe with all the circuits open or back up each circuit with an actual fuse. But then, I'm a computer geek; I think things like that are cool.:D
 
For Maintenance, not Flight....

I think I can sum up my preferences for breakers by saying that it has nothing to do with in-flight resets or th like - it has to do with ease of powering down always-hot stuff when I am doing troubleshooting, assembly/checkout, or other maintenance. In my EFIS-equipped airplane, I don't have switches for the stuff (like the EFIS displays, AHRS, EIS, etc) that I always want on when the airplane is hot. But occasionally, I'll want to power down a box when doing software upgrades or testing. A pullable cb serves to save me a switch! Sure, you could do it with fuses, but most people hide their breaker boxes pretty well - I have the breaker panel down by my leg, and it is simple.

I have nothing against fuses BTW - they work very well if circuit protection is your only goal. cb's can provide ADDITIONAL functions that can, in the end, save panel space on a complex airplane. For a simple plane, fuses work great!

Paul
 
I will only use circuit breakers, but it's preference more than anything else. I hate having to carry spare fuses. Circuit breakers are just easier.
 

Close but no cigar. No programmable circuit limits, just an assortment of pre-determined ones. I know I can simulate a programmable CB or slow-blow fuse with a Motorola chip; done it in EE Microcircuits class. But EE's my minor; I definitely don't want to tackle the task of designing a CPU/IO Controller circuit that would do what I have in mind. Aside from that one limitation, though, the vertical power system is pretty much what I had in mind.
 
I suspect professionals, which I shall define as off-site help, prefer breakers so all the builder has to do is ship off the panel, wait, then bring a few fat wires to the acres-of-breakers to complete installation of the delivered, wired panel. The pros don't have the subpanel available for mounting fuse blocks (or anything else). Makes for better modularization and a clearer demarcation for who's responsible for system performance.

Wouldn't it be nice if we had some pros respond to this post?

John Siebold
 
Socata uses switch breakers that offers both functions in one integrated unit. Much less wiring, and very cheap and easy to replace. I plan to use them in my -10.

Plus, with proper placement, a breaker gives you a visual and possibly even aural indication of a problem that a fuse doesn't.
 
John, I can't speak for all builds but Aerotronics, when they did my build, had my panel and all the structure forward. They ended up moving the left panel rib and adding another one to accommodate the EFIS. They also needed to be sure to clear the structure for the canopy hinge release. They ended up penetrating the subpanel for the EFIS head, the steam gauges, and the glove box. I can't imagine how they could do an install without at least the panel, subpanel, and panel ribs.

By the way, we do have some pros monitoring this list; I, too, would be interested to hear their thoughts. While I have my own opinions, I'm certainly no expert.
 
This has been a rather interesting thread to sit back and read! So far, only one person has come close - Paul Dye!

Basically, all of you who think we do it because "it's cool", or "it costs more" or "it's the way it's always been done", or any of the other proffered opinions are just dead wrong.

#1, we do what the customer wants. If the customer wants breakers, we use breakers. If the customer wants fuses, we use fuses. Either way, the customer has to run the exact same number of wires up to the panel, so that's a moot point as well.

Overally, if we are to assist a customer in choosing, we typically will look at the equipment first. If it's a VFR only plane with little to no avionics in it, them perhaps fuses are a great way to go. However, if you have a high end panel with high end glass in it, then CB's are the way to go. Why, you ask? Wll, Paul Dye pointed out a few reasons. Usually the high end EFISes are made up of a number of components (Screens, AHRS, MSU, etc..) that are all powered and need to be protected separately. Along these lines, when you have multiple screens with multiple boxes behind them, you'll need a way to be able to power up certain components separately from other components - when doing software loads, upgrades, calibrations, etc.. All the way from GRT, AFS, Chelton, Garmin, etc.. it's very usefull to be able to power up the components individually on the ground.

Personally, I think sometimes a mix of both is a good solution. Unimportant things could easily go on fuses, but important things should be on CB's. Believe me, we don't have a personal need to try and convince a customer either way, but some of the equipment does. Some things you should be able to reset. Those of you heavy iron drivers out there know that certain ground checks get done with certain breakers pulled and then reset (especially on the sparky's). Same goes with the higher end EFISes and their relative software loads, etc..Another thing is the ability to quickly and selectively shed load.

Anyway, I could ramble on about this, but I think that everyone gets the idea. We do what the customer wants within the reasonable limitations of his choice in equipment then use the equipment choice as a factor.

FYI, Fuse blocks for us are actually easier for a panel shop to do than CB's. No separate buss bars to attach, less wiring, etc.. and YES, we do an awfull lot of panels with fuses in them. Even on panels you see with lots of CB's, there are often time multiple fuse blocks behind the panel (going on the sub-panel or wherever).

In the end there are lots of reasons, but most of them are not what people have been guessing. It's usually well reasoned and logicall, along with customer desires.

Just my 2 cents as usual!

Cheers,
Stein
 
Socata uses switch breakers that offers both functions in one integrated unit. Much less wiring, and very cheap and easy to replace. I plan to use them in my -10.

Plus, with proper placement, a breaker gives you a visual and possibly even aural indication of a problem that a fuse doesn't.

What brand and model of switch-breaker are you looking at? I like the idea, but when I did some cursory searching, it looked like the best have a terribly low operation count - something like 5000 or 10000 cycles. Maybe that is not that low, but it seemed low to me.
 
Have to agree with Bob Collins above. I avoided the whole issue by putting in the Vertical Power VP-200 in my RV-8. No fuses, no breakers and no switches other than a bit of minimal hidde "back up" wiring to be sure I can start and fly if the screen goes black -- which it is not likely to do.

Of course some like the look of complexity with the more buttons, breakers, etc the better. Have to admit some tendencies that way myself! But, if I were doing it again I'd still go with the newer technology.
 
Yes you can!

No programmable circuit limits, just an assortment of pre-determined ones. I know I can simulate a programmable CB or slow-blow fuse with a Motorola chip; done it in EE Microcircuits class. Aside from that one limitation, though, the vertical power system is pretty much what I had in mind.


Actually, you CAN configure the circuit limts very easily. The circuits are divided into MAX 5A, 10A and 18A circuits. SO, for a MAX 5A circuit, you can set the CB value to either 1, 2, 3, 4, or 5 amps. Further, you can set the fuse type to either standard blow or slow-blow. And on some circuits, you can set them to be either on-off, dimmable, or soft-start. Further, you can configure if that device stays on or off during load shedding or a battery contactor failure, and what modes of flight the device is on or off.

Lots of flexibility with digital electronics! Here's a pic of the setup page:

DS1.gif
 
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Same with VP-100

Here's our other product showing the setup screen that allows you to set the CB value. This says that connector J6 pin 5 is set to a 7 amp breaker. The picture shown is the unit without the bezel on it.

ds2.gif
 
Here's our other product showing the setup screen that allows you to set the CB value. This says that connector J6 pin 5 is set to a 7 amp breaker. The picture shown is the unit without the bezel on it.

ds2.gif

Plus you can change the name from "Breaker" to a more descriptive name, such as 'Icom".
 
Ah, Ok. The description on the website made it sound like there were a set number of circuits at some preset Amp values. I stand corrected. Very cool.
 
It looks cool and cost way more money.
I used breakers for everything essential to flight (fuel pump, EI, Avionics master, flaps, alt field(although I decided I would never use it in flight), auto pilot, switched breaker for trim (Pilot side for trim cutoff)).
This is about the same as we did. At first we were going to use all breakers. After reviewing the aeroelectric information we now have 7 breakers and the rest are all fuses. Out of the way enough that you have to think and work a little to get to them, but could if you had to inflight. Resetting the breakers didn't work out so good for the SwissAir flight:(
 
You can easily see when a CB pops, specially in flight as oppose to detecting a failed fuse. This is specially true during flight, try to troubleshoot a failed item in flight. Also, you can disable a number of unnecessary items and leave only critical items on, if you have some power issue (dead alternator, etc). My avionics switch will activate one buss which is connected to an array of equipment, otherwise it would be many switches for each item. This way, I can disable second radio and other unnecessary HW to conserver juice.

The list can go on. It is certainly more expensive to do it with CB but it sure is worth it.

Mehrdad
RV7A
 
I am planning on fuses mostly. No breakers unless absolutely necessary (trim).

I want a totally "clean" panel.
 
I am planning on fuses mostly. No breakers unless absolutely necessary (trim).

I want a totally "clean" panel.

Tony,

I hear you but you want them on your flaps, alternator field, electronic ignition (if you have one.), and a few other places.

As for why I used them...

Chicks dig 'em :cool:
 
Yes, breakers for flaps, trim, alt field and maybe 1 or 2 others, the rest fuses. My fuse block will be accessable in flight
 
This has been a rather interesting thread to sit back and read! So far, only one person has come close - Paul Dye!

Basically, all of you who think we do it because "it's cool", or "it costs more" or "it's the way it's always been done", or any of the other proffered opinions are just dead wrong.

#1, we do what the customer wants. If the customer wants breakers, we use breakers. If the customer wants fuses, we use fuses. Either way, the customer has to run the exact same number of wires up to the panel, so that's a moot point as well.

Overally, if we are to assist a customer in choosing, we typically will look at the equipment first. If it's a VFR only plane with little to no avionics in it, them perhaps fuses are a great way to go. However, if you have a high end panel with high end glass in it, then CB's are the way to go. Why, you ask? Wll, Paul Dye pointed out a few reasons. Usually the high end EFISes are made up of a number of components (Screens, AHRS, MSU, etc..) that are all powered and need to be protected separately. Along these lines, when you have multiple screens with multiple boxes behind them, you'll need a way to be able to power up certain components separately from other components - when doing software loads, upgrades, calibrations, etc.. All the way from GRT, AFS, Chelton, Garmin, etc.. it's very usefull to be able to power up the components individually on the ground.

Personally, I think sometimes a mix of both is a good solution. Unimportant things could easily go on fuses, but important things should be on CB's. Believe me, we don't have a personal need to try and convince a customer either way, but some of the equipment does. Some things you should be able to reset. Those of you heavy iron drivers out there know that certain ground checks get done with certain breakers pulled and then reset (especially on the sparky's). Same goes with the higher end EFISes and their relative software loads, etc..Another thing is the ability to quickly and selectively shed load.

Anyway, I could ramble on about this, but I think that everyone gets the idea. We do what the customer wants within the reasonable limitations of his choice in equipment then use the equipment choice as a factor.

FYI, Fuse blocks for us are actually easier for a panel shop to do than CB's. No separate buss bars to attach, less wiring, etc.. and YES, we do an awfull lot of panels with fuses in them. Even on panels you see with lots of CB's, there are often time multiple fuse blocks behind the panel (going on the sub-panel or wherever).

In the end there are lots of reasons, but most of them are not what people have been guessing. It's usually well reasoned and logicall, along with customer desires.

Just my 2 cents as usual!

Cheers,
Stein


Exactly what Stein said. I work heavy aircraft avionics. Sometimes the electrons get confused as to who goes where. They need a little timeout. That is easier with a CB. The new thing coming out in large aircraft are software based CB's.
 
I chose to use fuses because...

  1. They don't take up any panel space.
  2. They are simpler and more reliable than circuit breakers.
  3. They are lighter than circuit breakers
  4. They are less expensive than circuit breakers.
  5. They are easier to install than circuit breakers.
  6. I do not intend to "reset" a blown fuse or breaker in flight.
The one exception to this is the use of a circuit breaker for the alternator field.
 
I have some reservations about fuse blocks. When a CB has a malfunction it destroys itself. If a fuse receptacle has one all the other fuses are at risk. Another is the placement. A lot of the fuse blocks I see are hidden from the pilots view. Not good for safety. Just my .02.
 
Both provide circuit protection. Aircraft electrical systems are NOT ticking time bombs waiting to self-destruct. Fuses are a good solution for circuit protection in a well-designed electrical system, breakers have some advantages, but not necessarily better. Fuse blocks can be mounted in a way to make them accessible in flight if one desires. To be honest, I would be reluctant to reset a breaker or replace a fuse in flight. If a circuit trips, I say land and see why. I am pretty sure that I can still fly without my entire electrical system.
 
Both provide circuit protection. Aircraft electrical systems are NOT ticking time bombs waiting to self-destruct. Fuses are a good solution for circuit protection in a well-designed electrical system, breakers have some advantages, but not necessarily better. Fuse blocks can be mounted in a way to make them accessible in flight if one desires. To be honest, I would be reluctant to reset a breaker or replace a fuse in flight. If a circuit trips, I say land and see why. I am pretty sure that I can still fly without my entire electrical system.

Great explanation. I had a difficult time mounting my fuse block so that they could not be accessible in flight but I did get them so that they could NOT be accessed in flight. After 12-years and over 2,300+ flying hours, I am happy to say that I like it so that I cannot get to them in flight. I have NEVER blown a fuse in flight. I have blown a fuse on the ground. I believe that it is safer to land and trouble shoot the issue than to try to trouble shoot it in flight. Since I am educated as an Electrical Engineer, I believe that I have a well-designed electrical system.

I have never seen a something go wrong with ONE fuse that caused the loss of the entire fuse block.

Bob Nuckles AeroElectric Connection lists all the reasons to use fuses. Paul Dye listed all the good reasons to use circuit breakers.
 
Bob Nuckles AeroElectric Connection lists all the reasons to use fuses. Paul Dye listed all the good reasons to use circuit breakers.

And just to be clear...I belive there are good places to use fuses too! ;) (I don't want to be branded as anti-fuse....)
 
If I had the cash Vertical Power is the way to go. Looks great and goes beyond just simple circuit protection. Fuses for now and eventually VP. It would be a relatively simple job to wire up from fuses to VP whereas Circuit breakers to VP would require a new panel.
 
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