Melting fuses!

rle1181 · 06-11-2014, 11:49 AM

Hello, I've got a 2013 sprinter 316bik which is not mobile and parked on a private campground site. Its hooked up to 110v year round. We ran heaters in the trailer all winter to prevent it from freezing because the campground is at a high altitude.

The trailer was idle from mid-December until early March. Once we started using it again we began to have electrical problems. Breakers flipping when barely anything was running, lights flickering on and off, etc. Then a few weekends ago we got to the trailer and could smell burning. I went to the electrical box and opened it to find the 15 amp fuse in line with the breaker to the refrigerator had melted. I removed it immediately and let the panel cool down. I replaced the fuse and everything seemed to work fine. Then last weekend same thing happened.

Anyone have any ideas? I would really appreciate it!

Thanks,

Ryan

**JRTJH** · 06-11-2014, 01:35 PM

If you had it "warm inside" and it was "cold outside" if there was any way that a critter could gnaw his way inside, you've probably got some wiring issues behind the converter/breaker panel.

It sure sounds like something is either corroded or shorted. My guess would be that if you remove the shore power cord and pull the breaker panel/converter, you'll find a nest behind it that was probably made from the insulation that used to be on your wiring.

I hope I'm wrong, but you really should do a really good inspection before you burn that thing down......

Good Luck

rle1181 · 06-11-2014, 02:12 PM

I've seen no signs of rodents, but i will look into that.

I was talking with a mobile rv repair guy today and he said that if your trailer is running on 12V dc the fridge can draw up to 30A. Is there a way that my fridge could be running off the batteries when i'm plugged into 110V? Because if the fridge is trying to pull 30A through a 15A circuit that could cause the excess heat, right? Thanks for the reply!

Javi · 06-11-2014, 02:16 PM

Very few if any of the new refrigerators are 12 volt capable, most are 110 or propane...

rle1181 · 06-11-2014, 02:22 PM

I don't know a lot about trailers, this is my first one. But, thats what i assumed because its got the auto button to go from 110V to propane if the 110V isn't available. The guy mentioned that about the 12V and it seemed like it might be a quick easy fix, so i was hoping that would be the problem.

**JRTJH** · 06-11-2014, 03:56 PM

What the tech was telling you is that if the reefer is a 12VDC/110AC/Propane model, on 12VDC it could draw up to 30 Amps. He is correct with that statement. As Javi said, very few "newer" refrigerators are 12VDC capable (although they all use 12VDC to manage the control board). The most a "newer" reefer should draw when operating on propane with the control board powered by the battery is 1-2 amps, any more than that and you wouldn't be able to drycamp for a weekend using the refrigerator.

Your refrigerator should not be the reason for that problem.

What 15 amp fuse circuit melted that is "in line with the breaker? the 120VAC breakers and the 12VDC fuses are not tied together at the converter or anywhere else that I know of....

Find out what else is on that melted fuse circuit, that will give you a clearer picture of where you need to focus your troubleshooting.

X-Treme · 06-11-2014, 04:31 PM

If you had either a short, or you were trying to "pull 30A thru a 15A fuse", that fuse should pop instantly. You should never have an issue AFTER a fuse. Sounds like maybe you have an issue BEFORE the fuse. Perhaps the panel itself? Perhaps where the hot side connects to the panel?

Ken / Claudia · 06-11-2014, 04:49 PM

Since we get to guess about the short, mine is some mice enjoyed the heated area over the cold season and had lunch on some wires.

rle1181 · 06-11-2014, 04:53 PM

Sorry if the stuff i'm saying doesn't make sense i really know very little about these systems and trailers in general.... This is a pic i took of the panel. If i take that top 15A fuse out (the one that melts) then my refrigerator and the main set of kitchen lights don't turn on. What i meant by "in line with the breaker" is they're both the top component.

X-Treme · 06-12-2014, 04:37 AM

And what I'm saying, is that a fuse shouldn't "melt". It should only "blow", which immediately stops the current from flowing. Once the fuse blows, no heat should build up anywhere, as there is no current flowing. You may get a little heat BEFORE this fuse blows, but if you have a dead short, the fuse should blow immediately. If the fuse takes a while to blow, it's not a dead short. It sounds like something is drawing just a little bit more than the 15A that the fuse is designed to handle. If the fuse is actually melting (plastic and all), then you've got a problem right in the panel at that fuse. I would say that the only way you would smell burning, and feel heat at the panel, is if you have a problem right at that panel.

{tpc} · 06-12-2014, 05:05 AM

What does the fuse holder look like with the fuse out? To me it sounds like a bad solder joint that is heating up the fuse holder and melting it. At least that is my first thought.

My second thought is that doesn't anyone else find it odd that a 30 amp breaker has a 15 amp fuse connected to it? When I look at the picture I see 3 breakers labeled 30amp, 20amp, and 15amp. Then I see 3 fuses 15 amp, 20 amp, 15 amp. When I see something like this, my mind says "this should have a 30 amp fuse".

Did you purchase the camper new or used? If used maybe the old owner just put whatever fuse in there and it worked for awhile. Now DON'T just go and toss a 30 amp fuse in there all willy nilly....if it truly is supposed to have a 15 amp fuse, that is just going to melt something somewhere else and could cause a fire.

What I would do is find the owners manual for that panel (its new enough that I suspect you can find it online if you don't have it) and find out EXACTLY what fuse should be in there.

I agree that most fuses should blow if drawing more than the specified current. However if said current is "creeping" up, you would be surprised at how long a fuse might last....and it could get very hot and melt in the process. I've actually done some extensive testing on some fuses here at work (for work purposes) and was surprised myself when the 20 amp fuse I was testing could hold at 40-45 amps for much longer than you think. Granted it wasn't this blade style fuse, which is easier to pop, but still.

If it isn't rodents, my money is on that fuse is the wrong size. Over time the fridge starts to draw a little more and then a little more current...fuse gets hot and melts, and that trips the breaker.

rle1181 · 06-12-2014, 06:24 AM

The trailer was purchased new and diagram next to the fuse panel says 15A. I have a pic of the connection point because the fuse is definitely loose when its in the panel.

**JRTJH** · 06-12-2014, 06:27 AM

As I said earlier, the 120VAC and the 12VDC panels are "side by side" but they ARE NOT connected... What you're doing is "looking at what's close" as being "connected" They aren't...

The 12VDC panel is wired to the converter which is mounted behind the AC circuit breaker panel. The 120VAC circuit breaker panel is separate, but adjacent to the 12VDC side.... The fuses and the circuit breakers "look' like they are "side by side" but they are in two separate and distinct panels that are not electrically connected....

There is no "circuit breaker/fuse" connection as you're imagining it. Each is it's own circuit and they don't interconnect.

If you don't understand the AC/DC relationship and are confused about this part of the concept, be extremely cautious about trying to troubleshoot your electrical system. It's very easy to get seriously hurt or damage equipment by "poking around" where you're not sure what you're doing.

It might be better to leave the troubleshooting to a qualified repair technician.

Good Luck

byrdr1 · 06-12-2014, 07:15 AM

Quote:

Originally Posted by rle1181

The trailer was purchased new and diagram next to the fuse panel says 15A. I have a pic of the connection point because the fuse is definitely loose when its in the panel.

I am not getting into the 12v vs 120v debate(but I agree with JRTJH 120v separate from 12v circuits) but if you look at the left side of the 15a 12v fuse it looks in the picture I can see a burnt looking lug. if your lugs are lose as you said, then you need to take some needle nose pliers and tighten that loop up. Your fuse should not be lose in the connection lug if so that would lead to your problem because the fuse is moving around in the lug per say. this would allow some heat to build up causing the fuse to blow to protect the circuit. I looked again at your photo the left lug is way more open than the right lug next to it. you can see were it needs to be tightened up. you can see at least on monitor that it is very open..
I am by no means an expert, but I did sleep at Holiday Inn last night..
Not really I took Electronics and Electricity for 2 years in school. and I have my fair share of electrical problems with campers over the years.
Main control board replaced in frig, new 65a 12v converter installed, electric heater fire.. just to name a few.
JMHO.
randy

{tpc} · 06-12-2014, 08:40 AM

Quote:

Originally Posted by JRTJH

As I said earlier, the 120VAC and the 12VDC panels are "side by side" but they ARE NOT connected... What you're doing is "looking at what's close" as being "connected" They aren't...

The 12VDC panel is wired to the converter which is mounted behind the AC circuit breaker panel. The 120VAC circuit breaker panel is separate, but adjacent to the 12VDC side.... The fuses and the circuit breakers "look' like they are "side by side" but they are in two separate and distinct panels that are not electrically connected....

There is no "circuit breaker/fuse" connection as you're imagining it. Each is it's own circuit and they don't interconnect.

If you don't understand the AC/DC relationship and are confused about this part of the concept, be extremely cautious about trying to troubleshoot your electrical system. It's very easy to get seriously hurt or damage equipment by "poking around" where you're not sure what you're doing.

It might be better to leave the troubleshooting to a qualified repair technician.

Good Luck

My apologies. It did seem redundant at the time. I guess I was confused by the breaker blowing at the same time the fuse was melting. I know better the differences between ac/dc circuitry.

Anyways, enough from me. Carry on.

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