In a recent thread, I suggested using a auto reset circuit breaker to protect the power supply wire for a electric coolant pump. Another Forum member (Old Toolmaker) thought a manual reset circuit breaker would be a better choice. This exchange got me to thinking: Why did Foretravel make such extensive use of auto reset circuit breakers in the 90's model coaches? (I don't know what kind of circuit protection was used in coaches built after that decade).
I grew up in the age of glass tube fuses being used in cars. Somewhere in the mid-80's car makers switched to blade type fuses, and these are still commonly used today (in a variety of sizes and shapes). I was not exposed to big RV electrical systems until we purchased our first-ever motorhome in 2013. Our '93 U280 uses blade fuses for protection of most DC circuits, with a few exceptions. We have some auto reset circuit breakers on the main DC panel in our central cargo bay, and a couple more on our isolator panel. Later model Foretravel coaches made extensive use of auto reset circuit breakers. The photo below shows the DC breaker panel from a late 90's Unicoach. I count 55 breakers on that panel.
The small metal body circuit breakers like the ones used by Foretravel are available in 3 types. Type 1 is "Auto Reset". Type 2 is "Modified Reset" and Type 3 is "Manual Reset". The paragraph below explains the difference:
"Bussmann 'Short Stop' circuit breakers are available in type 1 auto reset (12 and 24 volt DC options), type 2 modified reset (12 volt only), and type 3 manual reset (12 or 24 volt dual voltage use). Short Stop circuit breakers come in three mounting styles - standard right angle mounting bracket, parallel mounting bracket, and without a mounting bracket. Auto reset circuit breakers will trip in an over-current situation and will automatically reset itself after a period of time. If the fault condition is still present, it will trip again. Type 2 modified reset circuit breakers will remain tripped until the source current is removed from the breaker, at which time the circuit breaker will reset itself. This prevents the breaker from continuously cycling on and off. Type 3 Short Stop circuit breakers have a button on the end that will pop up when the breaker trips, and it must be manually pushed in to reset the circuit breaker."
Source of quote (above): Bussmann Automotive Circuit Breakers - WiringProducts. Ltd. (https://www.wiringproducts.com/bussmann-short-stop-circuit-breakers)
When I Googled the subject of DC circuit breakers I found there is no love lost for the auto reset type. Most opinions I found were in favor of using manual reset circuit breakers. It is generally believed that a circuit breaker that automatically resets only serves (in most cases) to postpone the inevitable failure of the faulty circuit or component. It also makes recognition of electrical problems more difficult, because the circuit may not completely shut down, but instead only turn off and on momentarily. Much better, they feel, to have the faulty circuit go completely dead, forcing the operator to take physical action to reactivate it. This action hopefully includes trouble shooting to determine the cause of the breaker opening.
SO, my question is: WHY did Foretravel use auto reset circuit breakers? I assume at least Type 1 and Type 3 breakers were commonly available when coaches were built in the 90's. Was there a good engineering reason to pick Type 1 breakers? Did the builders feel they were the best way to protect the DC circuits? Was it a matter of cost? Not much difference in cost between the types today...don't know about back then. Or was there some other logical reason I'm not seeing?
I open the matter to discussion. Any and all opinions accepted, along with actual facts if available.
In the meantime, unless somebody gives me a reason not to, I plan to replace the handful of auto reset breakers on our coach with Type 3. In the event of a electrical problem, I don't mind having to push a little black button to reset the breaker. But before I do that, I will attempt to determine what caused the breaker to open. That's the way things should work!
Headlights on older cars had auto reset breakers I have not worked on the headlights of newer ones as they never seem to have problems. I can remember driving at night and the lights just flashed off and on until I got off the freeway and fixed the problem. More than likely I cut the offending wire and repaired later.
Excellent question.
For the vast majority of owners and the vast majority of time, it makes no difference. Said another way, unless there is a problem that causes a breaker (or fuse) to trip (blow) all is well irrespective of breaker style. All do their primary job properly-- protect the wiring for devices they power.
From first hand information, I can tell you an automatic resetting breaker can make troubleshooting an electrical problem a nightmare. Had a dash A/C problem on our Foretravel. Worked well, then would go on "spells" of working for a few minutes, then getting warm again. Freon charge was perfect.
The Root Cause: The autobreaker up front that powered the condenser fans was weak and intermittently tripping. Finally caught it in the act. Replaced it with the same amp new breaker and worked perfectly from then on.
I suspect those who work on electrical issues on Foretravels, KNOW that these auto-reset breakers can be the cause of a lot of intermittent electrical failures and KNOW to check them when a failure is happening.
OK, but now that I am thinking about it, what is the point using a auto resetting breaker in any vehicle?
Assuming the breaker is "good" and functioning normally, it trips because there is a problem with the circuit. Unless it is a single isolated transient fault that does not recur, why "hide" the fact there is a problem by resetting the breaker without somehow alerting the operator? In the event of serious problems, like a short circuit or a frozen coolant pump motor, what purpose is served by opening and closing the power circuit multiple times until either the breaker fails (open or closed) or something overheats and catches on fire?
What is the thought process that concludes "auto reset" protection is preferable to "manual reset"?
There is also another type to be aware of. My 2006 Dodge Ram 3500 has a electronic fuse box. Computer decides what is hi draw and also what is low draw and will disconnect the circuit. If it sees three faults back to back it will regard the circuit as permanently failed and cannot be reset once the problem is resolved. They do have several spare circuits to modify to. Also with the correct proprietary scan tool you can increase or decrease power values for circuits. Definitely not DIY friendly. But wait there's more. Minimum cost to replace is $600 plus having to have it told that it is allowed to play with the new installation with that same proprietary scan tool at the dealer.
Scott
Maybe a safety issue. Lights, brake lights, turn signals, wipers etc are all self resetting on my coach.
If headlights go out on a dark road, they will come back on when breakers cools and allow you to find a spot to stop. They are also a good troubleshooting tool, When they trip, it is quite audible. I was driving one time and heard one tripping and resetting, traced the noise to the DRL breaker, sure enough one wire had chafed the insulation off, and it was touching the frame.
Chuck, I agree. Never understood the auto reset breakers. Makes it hard to know what is going on.
Not sure why they used it. Be pretty expensive to replace them all now.
Don't like the blade fuses. Don't like that they put that fuse panel down low in the bedroom where you have to get on the floor to see them, and most of the time I have to take them out to see if they are blown.
Just a quirky thing I guess.
I *think* that the original idea only considered a circuit overload that could be easily remedied and not the myriad other ways things can go wrong.
If you look at the top of a blade fuse you will see two places where you can probe the fusible link. With something on the circuit still trying to draw power, if yo measure voltage that fuse is open. No voltage closed, or still waiting to blow. Easy quick way to go down a row of fuses.
Jim: I can accept the wisdom of using auto reset breakers on safety items like headlights, turn signals, wipers, etc. At least with the headlights, the operator would be "notified" of a problem by the lights going off and on. But all the other dozens of circuits? Not the best choice, IMO.
Bob: Most blade fuses have 2 little holes in the top where you can quickly check continuity with a multimeter. Easier than pulling them out.
50 years ago Fiat's solution was four fuses for the headlights. One for each filament.
Yeah I know about checking them with the multimeter. It's still requires me to get down on the floor. I don't really like doing that anymore if I can help it. Unfortunately not only does it require me getting down on the floor, but I also have to look for the damn multimeter. I wish that they had put all that stuff in a cabinet high up instead of in the bed below. I'm not complaining mind you, it's just a wish not a rant.
If you are looking to buy a tool that will solve lots of issues, get one of these. I carry one in the coach and even keep one in the shop. It solved 3 issues at the Q. I bought a 20' extension for the one in the coach.
Power Probe III PP3S01AS Red 3S Circuit Tester w/Case & Accessories | JB Tools (https://www.jbtools.com/power-probe-iii-pp3s01as-red-3s-circuit-tester-w-case-accessories/?gclid=EAIaIQobChMIvoeVx6m45wIVjYbACh2ayg9SEAQYAyABEgIgRPD_BwE)
Whap! That's my hand slapping my forehead. Never thought about that!
jor
You forgot to add "And I also have to find my reading glasses". Yes, I know all about that, and I feel your pain. :'(
Getting old sucks, but it sure beats the alternative.
Craneman, that's something I probably could use if I didn't just spend a whole bunch of money on other things I would be ordering it today. Maybe my wife will get it for me for my birthday! :)
Nah I wear trifocals. Always have my reading glasses on and my distance glasses!
I'm due for an eye exam, and a new set of trifocals. Right now I'm paying attention to near or close as I think I'll have a second pair made as occupational glasses with, probably, near at the top. I used to have my glasses made that way for programing the machine tools and reading digital displays since the manufacturers like to put the control panel above eye level.
That's a interesting idea - never considered that trifocal layout. I also wear trifocals, and often find my neck in painful positions trying to see through the bottom of the lens.
I keep a pair of cheap drugstore reading glasses in my tool box. They are approximately the same as the bottom section of my trifocals. I wear them when working in close quarters and find they are more comfortable.
My eyes have drifted in different directions and I get wicked headaches with cheaters.
$60 and you will have a led lite up when fuse blows.
I am not going to order these right away, however this makes finding a blown fuse easier. If ever I started having repeated blown fuses, I'd sure order the proper following fuse, Amazon one day, until issue was corrected.
Kaper II NEOPlex 10 Pack-Intelligent 15 amp ATP Knife Blade Fuse (They Glow When They Blow) Amazon.com: Kaper II NEOPlex 10 Pack-Intelligent 15 amp ATP Knife Blade Fuse... (https://www.amazon.com/dp/B00JBO0IJ4/ref=cm_sw_r_cp_apa_i_qmktEb2YX0NYY)
Kaper II NEOPlex 10 Pack-Intelligent 5 amp ATP Knife Blade Fuse (They Glow When They Blow) Amazon.com: Kaper II NEOPlex 10 Pack-Intelligent 5 amp ATP Knife Blade Fuse... (https://www.amazon.com/dp/B00JBO0HYU/ref=cm_sw_r_cp_apa_i_hoktEbT1KCGNF)
Kaper II NEOPlex 10 Pack-Intelligent 25 amp ATP Knife Blade Fuse (They Glow When They Blow) Amazon.com: Kaper II NEOPlex 10 Pack-Intelligent 25 amp ATP Knife Blade Fuse... (https://www.amazon.com/dp/B00JBO0K6A/ref=cm_sw_r_cp_apa_i_ttktEbC5XN715)
Kaper II NEOPlex 10 Pack-Intelligent 10 amp ATP Knife Blade Fuse (They Glow When They Blow) Amazon.com: Kaper II NEOPlex 10 Pack-Intelligent 10 amp ATP Knife Blade Fuse... (https://www.amazon.com/dp/B00JBO0IA8/ref=cm_sw_r_cp_apa_i_OuktEbSXYTZF2)
Kaper II NEOPlex 10 Pack-Intelligent 30 amp ATP Knife Blade Fuse (They Glow When They Blow) Amazon.com: Kaper II NEOPlex 10 Pack-Intelligent 30 amp ATP Knife Blade Fuse... (https://www.amazon.com/dp/B00JBO0KH4/ref=cm_sw_r_cp_apa_i_QvktEbJJ5VRCY)
Kaper II NEOPlex 10 Pack-Intelligent 20 amp ATP Knife Blade Fuse (They Glow When They Blow) Amazon.com: Kaper II NEOPlex 10 Pack-Intelligent 20 amp ATP Knife Blade Fuse... (https://www.amazon.com/dp/B00JBO0JNO/ref=cm_sw_r_cp_apa_i_yxktEb612BZEQ)
Thanks jack.those are pretty cool.