Auto Reset Circuit Breakers vs Fuses

[rvan2000]

Hi there, just became the proud owner of a 2007 Sundance 2900 MK and my first impressions of the fifth wheel are very positive. This is my first post on any kind of a forum like this but have a question in regards to my fifth wheel. I noticed that the factory used auto reset circuit breakers for power distribution to most of the 12V loads on board. Coming out of the automotive industry I was always taught that every power wire had to be protected in the event of a dead short. My concern is that the auto resetting feature of the CB may continue to cycle power to a dead short with some scary consequences.

I can see auto resetting for the brake feed and other critical functions but believe either fuses or manual reset circuit breakers might be a better choice for the other circuits.

Anyone have any thoughts on this? Am I anticipating a problem that doesn't exist??

 

[danemayer]

Hi rvan2000,

Congratulations on the new-to-you Sundance and welcome to the Heartland Owners Forum.

I think you'll find that with one exception, the 12V DC mini-circuit breakers provide power to circuits that are powered when you hold down a switch - to operate a slideout for example. Most of the exposure to a short is probably after the switch. You'd stop pushing the switch after a few failed tries.

It's possible that a short between the breaker and switch could cause the breaker to recycle repeatedly, but usually the auto reset takes a few seconds to recover. I suspect the breaker would fail completely after a number of repeated trips, opening the circuit.

The one exception is the breaker that connects the battery to the fuse box and Power Converter. That circuit is constantly powered anytime the battery has a charge or you're on shore power. That breaker is a manual reset type.

 

[rvan2000]

Thanks so much for your insight, makes sense if the 12V load is on a momentary switch as you say.

The engineer in me might lead me to change over to manual reset CB's across the board (except the brakes, and converter) so that I am forced to investigate and correct any electrical gremlins (like a dead short) that rise up.

Thanks again

 

[avvidclif]

Maybe they work on the theory that if we hit it enough times with voltage the short will clear itself??

 

[Jesstruckn/Jesstalkn]

In my opinion the way the factory set it up is the best way.
Also you do not want to put a Auto reset CB on the convertor. That one should be your only manual reset breaker.


Sent from my XT1585 using Tapatalk

 

[Silverado23]

It would become very annoying to have to replace a fuse every time I put my jacks down or up or the slide-out in or out as the stall current would blow the fuse instead of simply trip the breaker in a temporary overload situation.

Or worse yet two situations that were not my RV but had fuses where circuit breakers would have been better choices.
The slides on SOB that I helped new owners track down were fused and the fuse box was placed in an inaccessible location when the slides are closed up. We ended up having to have the owner cut an access panel in the coroplast to access the slide motor. Extend the slideouts manually and then replace the fuse to retract the slides fully in.

Another situation that a circuit breaker would be better was the time I helped a neighboring RV with a chairlift for their spouse. The weather was cold and the motor would stall out fairly quickly. I think the guy ran through a half dozen fuses with his wife perched up on the lift. He ran out of fuses and then had to track more down while she sat on the lift waiting.... The guy supposedly was heading to town the next day or two to purchase a circuit breaker instead of the fuses.