Does Nobody Ever Wonder Why a Fuse Blows?

[nomad297]

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

[OldRadios]

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]

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]

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]

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]

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]

I've had blown 12v fuses twice, both were caused by bad light bulbs. Both took a little investigation to find.

[D___M]

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]

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]

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]

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

[Peg_Leg]

1st fuse - thought is circuit working fine then "POP" could have been a spark from flipping a switch. Not a big worry.
2nd fuse - now for the fun. Sherlock Holmes time.

I've lost more fuses than I've replaced. Seems when you buy them there in a pack of 2 or 5. Guarantied next time I want one, I'm not going to find the rest of that pack.

[nomad297]

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.

This is exactly the type of thing that worries me. Some people think if that 5 amp fuse keeps blowing, let's try a 10 amp. Heck, if the 10 amp won't do the trick, I bet a 30 amp will fix it.

Bruce

[tpi]

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?

Generally and unfortunately there almost always has been a real problem. Although I'm sure it happens, I can not think of one time where a fuse blew and just replacing it permanently solved the problem for me.

[FlatBroke]

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.