Electrical help..short or not

[RandyG]

Just curious if anyone could give me some suggestions on this little problem we are having. We are restoring (amatuer level) a 1975 31ft rear bath. Recently I replaced the univolt with an Xantrax unit. I managed to save the old fuse panel thank goodness. I installed this about 3 months ago. Now for some reason the 1st fuse (20amp purple wire that goes to the rear bath lights, switch, and hallway overhead light) keeps melting. The wire itself gets EXTREMELY hot and starts smoking and the end of the fuse always melts now. I am trying for the life of me to figure out what in the world could be causing this. Does anyone have any suggestions on what to do first? I am pretty handy but I am not the greatest at the electrical problems like this. Any help would greatly be appreciated. Thanks to all!

[goransons]

Since the problem has occured have you done any major work on the rear area of the trailer? Perhaps a screw went through a wire? Sounds like you have a pretty solid short circuit going if you're over heating and smoking from that circuit.

[RandyG]

I did screw in the fuse panel to the wall as well as the Xantrax inv. I think they are far enough away from the entry where that wire comes in. I wasn't sure if it might be the switch in the bathroom or not but I guess you are right it would have to be something pretty hefty to smoke a wire. I do have the trailer plugged into the wall but I am not sure why out of nowhere it would start doing that.

[goransons]

Might make sure that contacts on the back of the fuse panel aren't getting against the skin. You can also with the power off check with a volt meter for continuity between that circuit and the shell of the trailer.

[Gene]

You are fortunate the fuse melts, though it should fail quicker, before the wire gets so hot. You have a dead short—i.e., something has made a very good (not in the sense of good is wonderful) complete circuit. Goransons may be correct since a screw could probably connect a hot wire to the trailer body which acts as a ground. It could be a broken wire in a fixture, the switch, an old wire where the insulation has finally worn off and shorted to the trailer body, or the wiring for the old fuse panel. This is not a complete list. You could have crossed wires somewhere when you hooked up the new converter and—perhaps the hot and ground wires to the fuse panel for that particular circuit are crossed. Or, did you somehow connect a 120 v. wire to a 12 v. one?

Does anything work before the fuse blows? If some things do and some things don't, the problem is probably not in the "don't" area, but between do and don't or at the ends of that area.

You may not have know much about electrical systems before, but you soon will get a practical education tracing down the problem. Electrical circuits are very logical, so just follow things through methodically eliminating one thing at a time. If you can get to some wires, and you've eliminated everything else, you may have to pull them out, but first attach new wires to them very securely so you can have new ones ready to use.

Now's the time to buy a multitester to make sure you have 12 v. DC where it should be and 120 v. AC where it should be. You will find that tester a wonderful toy for years to come to check all sorts of things like amps and ohms and volts and amaze your friends when you show them that their houses only get 117.6 v. (or whatever) instead of 120 v. (or they will think you had too much aluminum to eat).

Gene

[bibbs]

sounds like the connection is loose and it is arching causing the heat and melting the fuse

check the fuse holders' screw connections

Bibbs

[RandyG]

When I first put the fuse in all the lights from the back hallway and the overhead bathroom lights work. So everything will work with the fuse in but then the lights will flicker and you can smell the fuse getting hot. I guess I will be picking up some tools Friday. When I put a new fuse in the panel my inverter fan comes on as well so I guess I will test out everything to see what is grounding it. I really appreciate all of your help. I am wanting to have this thing done and ready in the next 2 months.

[ROBERTSUNRUS]

Hi, basic diagnosis:

(1.) Shorts, blow fuses.

(2.) Shorts and circuit overloads, trip circuit breakers.

(3.) Fuses and circuit breakers [correct size] protect wires and circuits.

(4.) Poor connections create heat and melt fuses and wire insulation.

(5.) Poor grounds cause things to work poorly.

(6.) Open circuits, hot or ground, cause things to not work at all.

(7.) Intermittant problems is a whole different animal.

[Lumatic]

This is a long shot I'm sure, but there are some 40 amp fuses which are the same size as the 20 amp fuses in some of the Univolts.

[Foiled Again]

Originally Posted by Lumatic

This is a long shot I'm sure, but there are some 40 amp fuses which are the same size as the 20 amp fuses in some of the Univolts.

AND THE PROBLEM WITH THAT IS....

If you've got a 40 amp where you need a 20 amp, you've turned the WIRE into the fuse! Fuses are designed to blow and give their little lives to protest the wiring and the dwelling from burning. If the fuse isn't blowing until the wire's insulation is smoking you've got a fuse that's the wrong size (this is akin to burning down your house by sticking a penny in the fuse box).

[Inland RV Center, In]

Never, ever, increase fuse sizes in the trailer, because one continues to blow.

To do so, is asking for a fire.

There is a partial short within that circuit. A bulb can cause that.

Take all the bulbs out, and see what happens. If the circuit clears, then reinstall the bulbs, one at a time, and observe the results.

Or, get an "ohm" meter, and look for the problem, first killing all the power to the fuse panel.

Andy

[Foiled Again]

Originally Posted by Foiled Again

AND THE PROBLEM WITH THAT IS....

If you've got a 40 amp where you need a 20 amp, you've turned the WIRE into the fuse! Fuses are designed to blow and give their little lives to protect the wiring and the dwelling from burning. If the fuse isn't blowing until the wire's insulation is smoking you've got a fuse that's the wrong size (this is akin to burning down your house by sticking a penny in the fuse box).

fingers fast, brain farts

[john hd]

if you cannot fix it with a hammer then it is probably an electrical problem.

follow andy's advice and report back.

john

[Lumatic]

Originally Posted by Foiled Again

AND THE PROBLEM WITH THAT IS....

If you've got a 40 amp where you need a 20 amp, you've turned the WIRE into the fuse! Fuses are designed to blow and give their little lives to protest the wiring and the dwelling from burning. If the fuse isn't blowing until the wire's insulation is smoking you've got a fuse that's the wrong size (this is akin to burning down your house by sticking a penny in the fuse box).

Absolutely.

Just in case I was not clear, I was not suggesting putting a 40 where a 20 belongs. In some univolts the 40s are the same size and look very much the same as the 20s. If you put a 20 where a 40 belongs
she's a gonna blow. There are other Univolts in which the 40s are much bigger.

Nevermind what you thought I meant. I thought I meant to say what I thought. It's a 60s thang.

[bibbs]

Is the fuse clipped tight in its holder? Is there a good connection at both ends of the fuse? If the fuse holder clip was loose it could get hot. You might need a new fuse holder

bibbs

[RandyG]

Well, I didn't get the chance to do any electrical work today because my wife wanted some rotted flooring cut out (seems like the toilet might have leaked). I am definitely going to try all the suggestions. I think it's time to get an ohms meter and start learning. My wife and I are really chomping at the bit to get this thing done. I will get to it in the morning and let everyone know what happens. Sometimes I think it would be a heck of a lot easier to have just bought a newer one but we had always wanted a vintage airstream so I am not gonna complain. Thanks again everybody.

[ROBERTSUNRUS]

Originally Posted by RandyG

Just curious if anyone could give me some suggestions on this little problem we are having. We are restoring (amatuer level) a 1975 31ft rear bath. Recently I replaced the univolt with an Xantrax unit. I managed to save the old fuse panel thank goodness. I installed this about 3 months ago. Now for some reason the 1st fuse (20amp purple wire that goes to the rear bath lights, switch, and hallway overhead light) keeps melting. The wire itself gets EXTREMELY hot and starts smoking and the end of the fuse always melts now. I am trying for the life of me to figure out what in the world could be causing this. Does anyone have any suggestions on what to do first? I am pretty handy but I am not the greatest at the electrical problems like this. Any help would greatly be appreciated. Thanks to all!

Originally Posted by ROBERTSUNRUS

Hi, basic diagnosis:

(1.) Shorts, blow fuses.

(2.) Shorts and circuit overloads, trip circuit breakers.

(3.) Fuses and circuit breakers [correct size] protect wires and circuits.

(4.) Poor connections create heat and melt fuses and wire insulation.

(5.) Poor grounds cause things to work poorly.

(6.) Open circuits, hot or ground, cause things to not work at all.

(7.) Intermittant problems is a whole different animal.

Hi, only a poor connection at the fuse holder, [or not in this case] direct heat like in a flame or fire, will melt a fuse. [#(4.) above.] And [posts #6 & 15]

[RandyG]

Thanks, I think I am going to take the fuse panel off the wall and clean the connections (clips). It seems to me that the post that screws in and holds the wire is black versus the other ones which are silver. I don't know if that makes any difference but I am determined to get it fixed tomorrow. That is my main objective. Thanks

[aircooled4]

It sure would be nice if the weather here in Wisconsin would allow ME to get out and work on my Safari... I hope it all goes well for you!

[azflycaster]

I would also verify the size of the fuse that is heating up. Maybe the PO tried to troubleshoot the problem by installing larger fuses. Also make sure that nothing is shorting out the back side of the voltage distribution board to ground.