So often on this forum I read where somebody is having or had an electrical problem only to discover that "it was just a blown fuse" or tripped breaker, as if that was the problem, and when they replaced or reset it, the problem is now fixed.Sure, I suppose there can be a defective fuse here or there, but it doesn't seem as though a blown fuse or tripped breaker raises a red flag, telling most people that there is a problem somewhere other than in their fuse box.When a fuse blows in your rig, do you just replace it and not think twice about it if it doesn't keep blowing? Or do you take the time and effort to discover the real problem?Bruce

I guess it depends on the fuse... auxiliary fuses tend to blow and are low amp so I don't worry too much about them, and my AC circuit breaker will trip if I'm not ordered about turning things on.On the other hand, when the thermal fuse blew on my heater I made damn sure I had the heater cleaned out before I replaced it and turned it back on.

If you replace a fuse and it blows again, check it out. On my front jacks I have overloaded in the past and blew a fuse. It was my fault, the rear stabilizers were down and I needed to raise the front a tad more. That was too much and blew the fuse. Replaced and kept that in mind!

Unless you've only got one spare fuse in your inventory, I'd just replace it, and then wait and see. There is no telling what caused the fuse to fail, and it may just be that rare "bad fuse". But, it does indicate that there is some sort of problem, which may or may not happen again.Typically, I'll just replace or reset the fuse/breaker and see what happens....if it trips again, I'll investigate...if not, I'll continue to enjoy my trip!Same goes for the GFI outlets. Sometimes it's an issue, but sometimes, it's just that the outlet is getting old, and more sensitive....but you also have to be aware that these are safety aids that may save your life, so don't take them lightly.A good point is made in the OPs comments....they usually trip for a reason...find out why, before you have an electrical fire, that would surely ruin your trip!

Fuses are mechanical connections and die of their own accord. The old glass fuses could get a bit warm if the connections were not clean and there was a lot of current passing and in turn the inside end connections would melt open leaving you with a perfectly looking fuse that was bad. In my service business we probably have changed over 50 thousand fuses in the last 40 yrs. I would bet over 50% were fuses that just got tired.

rseymour21 wrote:If you replace a fuse and it blows again, check it out. On my front jacks I have overloaded in the past and blew a fuse. It was my fault, the rear stabilizers were down and I needed to raise the front a tad more. That was too much and blew the fuse. Replaced and kept that in mind!Depends on how it blows also, just melted likely a overload, may have been temporary, metal flashed to the inside of the fuse time to find a dead short (but not always).I did computer repair in an earlier life. Came across a flashed fused for a dead Point of Sale register, checked my supply of that particular fuse size. I check for obvious shorts or bad components, seeing none installed new fuse and powered up. Loaded and ran, I hung around for about 30 minutes, no further issues.

Does Nobody Ever Wonder Why a Fuse Blows? | Good Sam Community

24 Replies

OldRadios
Explorer
Jun 18, 2014
If a second fuse (12 VDC system) blows always check it out.

If a circuit breaker trips (120V AC system) it could very well be that the supply voltage you are plugged into has dropped too low (voltage drops amount of current required goes up). Running AC motors at low voltage shortens their life.
frankdamp
Explorer
Jun 18, 2014
Michael:

Do you run the slide until the motor/drive system stalls out at the end of its travel? A stalled electric motor with the operator's finger still on the switch will blow a fuse in milliseconds.

A well-designed system would stop the slide at its limit switches regardless of whether the operator still had the switch depressed, but so often, "well-designed" and "RV" are mutually exclusive.
Gonzo42
Explorer
Jun 17, 2014
mgirardo, you might have an intermittent short to ground. It will probably take a lot of your time to trace the whole offending circuit and look for a damaged spot of insulation, or a stray strand of the wire at a connection but touching ground once in a while.
mgirardo
Explorer
Jun 17, 2014
I have a repeat offender that I wish I could figure out. I've had it at the dealer twice looking for the problem and they have no idea. Our living room slide, which is the smaller of the two slides (maybe 12 feet long) blows a 30 AMP fuse every once in a long while. In the last 3 years it has probably blown 2 fuses. It's the only thing on that fuse and it only happens after the slide is in or out. It has never happened while the slide is moving. I let off the switch as soon as it is in or out.

I've searched and so has the dealer. I'd love to figure out what the problem is, but I haven't had any luck figuring it out.

-Michael
RVWithTito
Explorer
Jun 17, 2014
I can relate. My son bought an older Nissan that has some electrical issues. He keeps taking fuses from my spare RV fuse stash instead of troubleshooting his wiring problem. Grrr!
stickdog
Explorer
Jun 17, 2014
I've had blown 12v fuses twice, both were caused by bad light bulbs. Both took a little investigation to find.
D___M
Explorer
Jun 16, 2014
If you replace the fuse and it doesn't blow, there is no problem. It was a transient problem. The world is an imperfect place.
bukhrn
Nomad
Jun 16, 2014
ChopperBill wrote:
Had a friend that bought a brand new mobile home. The fuse for the water inlet heat tape kept blowing and he kept replacing it. Home burnt to the ground that night. They barely made it out.
And This is the real disconnect in this scenario, if you blow a fuse, replace it & move on, if the same fuse blows again, (especially rather quickly), check it out & find out why. No way would I just arbitrarily keep replacing the fuse. :(
wa8yxm
Explorer III
Jun 16, 2014
I do have a spare fuse inventory.. So if I know what blew it (Example if I was working on something and caused a short) well I fix the problem then replace the fuse.. Else I replace it and see if it blows quickly, If it does I get to work trouble shooting till IN find the problem (I use a test lamp in place of the fuse during this step).

Test lamps are wonderful inventions.. Often they are more useful than a voltmeter for trouble shooting, I have 3 or 4 of 'em around here and make more when needed.
Gonzo42
Explorer
Jun 16, 2014
I have a dedicated plastic box just for all the electrical spares and tools:

Electrical Spares/Tool Kit
Awning Repair Tape LifeSafe RE3848
Disc Brake Quiet
Electrical Grease
Fuse Circuit Tester HF 67724
Fuse Puller/Tester Bussmann FT-3
Fuse, 10A
Fuse, 15A
Fuse, 20A
Fuse, 25A
Fuse, 30A
Fuse, 40A
Fuse, 5A
Fuse, 7.5A
Hose Washers
Kwik Klips 1/2"
Kwik Klips 3/8"
Lamp Sylvania 1156 LL
Lamp Sylvania 1157 LL
Lamp, Amber Sylvania 3357A LL / 3457A LL
Multimeter HF 98025
Trailer Light Tester HF 66526
2 small Flashlights

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Does Nobody Ever Wonder Why a Fuse Blows?

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