FOUND: Burning Electrical Smell this morning

Hi all, Hope you might be able to point me in the right direction before I have to pull up stakes and take my BH to a repair facility. We have an 2012 3585rl. We are at a park in West Tucson for the winter and I am plugged into 50 amp shore power. Started getting a burning electrical smell this am after turning stuff on. Had gotten up and turned on furnace, Coffee pot was on and working, fireplace was on the high setting and all of the main ceiling lights were on. Decided to open the 12 volt fuse box. That is where the smell was coming from. Panel was warm to touch so started pulling fuses. #1 20 amp fuse was blown. #2 20 amp was really warm and when I pulled that all of the overhead lights went out. Red light came on. when putting it in back in it started sparking because i am assuming it was making an electrical connection, but was instantly hot to my fingers. Since there is no wiring diagram for the 12 volt fuses I am not sure what the #1 fuse that is blown goes to. Now that I have the #2 fuse out and the over head light are off the smell is going away. Any ideas out there?

Thanks

Re: burning electrical smell this AM

Sorry, the 2 fuses I pulled are blue 15 amp.

Re: burning electrical smell this AM

Also the little soldered spot to the left of the fuse is usually shiny and the one next to the #2 fuse has discolored to grey. Seems that would indicate it got overheated...yes?

Re: burning electrical smell this AM

There should be a fuse legond on the fuse panel cover.
On mine, the first 15 amp fuse is for the antenna booster.

Peace
Dave

Re: burning electrical smell this AM

If you have a DVM that reads DC amps, and a couple of alligator jumper connectors, you should be able to put the meter in place of each fuse and get a readout of what is going on. Start with all loads (lights, etc) on each circuit under test turned OFF, and tun the loads on one at a time while observing readings on the meter. A BIG jump in amps draw would make you suspect that device or the wiring to that device. Look for discolored wiring or connections. Be sure your 12 volts is 14.4 volts or less with the converter on (the converter has a limited 14.4 volt boost quick charge mode), and about 12.6 volts with the converter off. You should be able to turn the converter off with a labeled AC circuit breaker.
Fuses do blow by melting internally, but are normally not hot to the touch. A little contact cleaner/restorer on any electrical contacts (including fuses) might help, too.

Good luck!!!

Re: burning electrical smell this AM

vicrider said:

Also the little soldered spot to the left of the fuse is usually shiny and the one next to the #2 fuse has discolored to grey. Seems that would indicate it got overheated...yes?

Click to expand...

Bit of a guess: different color might indicate a cold solder joint.

Re: burning electrical smell this AM

vicrider said:

Hi all, Hope you might be able to point me in the right direction before I have to pull up stakes and take my BH to a repair facility. We have an 2012 3585rl. We are at a park in West Tucson for the winter and I am plugged into 50 amp shore power. Started getting a burning electrical smell this am after turning stuff on. Had gotten up and turned on furnace, Coffee pot was on and working, fireplace was on the high setting and all of the main ceiling lights were on. Decided to open the 12 volt fuse box. That is where the smell was coming from. Panel was warm to touch so started pulling fuses. #1 20 amp fuse was blown. #2 20 amp was really warm and when I pulled that all of the overhead lights went out. Red light came on. when putting it in back in it started sparking because i am assuming it was making an electrical connection, but was instantly hot to my fingers. Since there is no wiring diagram for the 12 volt fuses I am not sure what the #1 fuse that is blown goes to. Now that I have the #2 fuse out and the over head light are off the smell is going away. Any ideas out there?

Thanks

Click to expand...

Take it from an ole electrician: First turn off all power and tighten every screw connection. Second on each of the plugs for the fuses look closely with a flash light for even the slightest discoloration. If you see any the first step is to take some needle nose pliers and tight them slightly for a better blade contact with the fuse. Third look for the cold solder joint spoken of, although this will be pretty hard to spot unless it is really bad. Here again, a cold joint will appear dull while a good quality joint usally is shinny. That is if the character who did the work used the correct solder. If you don't find any thing suspect after that, try the ammeter. But, unless you got a base reading or happen to get a really high reading you won't know much more after the test. About the only reason you should get an instant hot fuse is a "dead" short down stream my friend. If at this point you haven't found anything, try removing all the bulbs and turning on the lights. If you have a shorted base connection you'll still get a hot or blown fuse. If you don't get a bad condition start putting one bulb back in at a time until the problem shows up. This should narrow you problem to either wiring to that light or the light itself.

Also, if you can look at the back side of the board / mount for all wiring. I've seen dirt, debris, even a mounting screw that was to long in a panel cause real problems similar to the one you describe. Once found a mounting screw that was simply too long and went through the wall and had rubbed through the insulation on wiring running up the wall. Best weapon you have for finding this problem is actually your eyes and a good flashlight. You need to look closely and steadily at every connection and inch of wiring you can see related to the fuses in question.

If there is anything else you think of to ask or just want to talk about the problem more (270-635-3693). I retired after 40 years as an industrial electician chasing crazy stuff like this. I don't have a Bighorn, but might be able to help you with your troubleshooting. Good luck my friend. Sometimes this kind of problem gets to be a real pain to find.

Tom

Re: burning electrical smell this AM

High heat is almost always a poor electrical connection.

Re: burning electrical smell this AM

Also low battery voltage will cause a high amp draw. Which in turn will cause high heat in 12V curcuits. You could have a sorta loose ground somewhere. In the fuse panel or at a light socket. A shorted to ground 12V (B+) will blow a fuse right now. A loose ground will create alot of heat until something melts. Its known as letting all the "smoke" out of the wire.

Re: burning electrical smell this AM

Thank you all for the help. This forum is awesome.
The connection for the wire that controls the overhead lights in the coach was loose at the back of the fuse block. It got so hot that the wire turned a little brown at the back of the fuse block. What I am hearing from you all is that the loose connection created the heat that burnt the wire, but the amperage didn't go high enough to blow the circuit. Am I correct?

Re: burning electrical smell this AM

It's what I call the bad connection syndrome. A poor connection with even a moderate amount of circuit current generates heat (Power or heat = Current Squared times the resistance). The resultant heat causes connection corrosion, which makes the connection resistance higher. That in turn again makes more heat, and in and endless circle finally resulting in smoke and the wire connection finally breaking down.

Glad you found the problem!!!

Re: burning electrical smell this AM

A high resistance (loose) connection such as you found, will cause heat.

Here's a very simplified explaination; http://www.ndt-ed.org/EducationResources/HighSchool/Electricity/resistance.htm

Glad you found it. Trace

Re: burning electrical smell this AM

High resistance normally will not cause a fuse to blow unless it is a direct short to ground. High resistance, loose connection, will just cause high heat in a wire and if left long enough will cause the wire to melt. Most electrical 12V curcuits are fused at just enough to handle whats on them. If you put a higher amped fuse in a curcuit....you will let all the smoke out of the wires.