RV Doctor – I’m Having Issues With Main Fuse In My RV

author image

September 22, 2009

Dear Gary,

While closing my slides I found the main (30A) fuse blown. I returned home and replaced the fuse and set up the coach and plugged into my AC electrical source and opened up both of them. We had some bad weather coming through our area so I went out to close the slides and the main fuse was blown again! I replaced the fuse after opening the slides and it was okay. My book doesn’t show an electrical diagram for the circuits and I am lost. Neither time could I smell any type of smell indicating bad wiring. – Randy Serice, (Lake Charles, LA)


There are a couple of things to check Randy. Be sure you have a healthy battery in the system. A sulfated battery may have some internal arcing that could cause a heavy fuse like that to blow.

Also, look for any resistance to the movement of either slide. Check the slide mechanism closely for corrosion, binding, rust, debris, etc. Any perceived drag on the movement could cause the fuse to blow.

Lastly, check the battery wiring connections, especially on the ground side of that circuit. I’m not aware of any inherent deficiencies with your coach, but in some cases, an undersized ground cable anywhere in the circuit could cause overheating which could also blow the fuse.

You can eliminate the slide mechanism and the mechanics of the system by using a fresh battery connected directly to the slide circuit. If it works fine independent of the coach, the problem is in the wiring. If it still blows fuses, chances are there is a mechanical binding in the components somewhere.

(Please feel free to comment, however, please also note that due to the volume of communications I receive from multiple channels I cannot guarantee a personal response in every instance. However, questions of an overall general interest may be considered and published in an upcoming RV Doctor column.)

Leave a Reply


  1. Pingback: www

  2. Pingback: my url

  3. keebler

    NOT all rv’s with slides are 12 volt—-many are Hydraulic—and the Brake has to be set-,some the Jacks must be Down, and the engine running,
    My 2 cents


    bedroom slide does not extend, no motor sound, front slide works ok. where should i start looking? 2002 travel supreme select….where are the fuses andswitches located?

  5. Gary Hollmer

    To Dick:

    I have never heard of any slideouts operating on 110V. We have had two Class “A” Winnebagos and currently have a 5er. All operated on 12v.

    Gary’s answer to Randy is good advice.


  6. Dalton Tamney

    I have a 28′ trailer and a 38′ Alfa Class A and the slides in both of them work off the 12 vol system. I am anxious to hear if Randy can solve his problem using Gary’s suggestions.

  7. Well my 2003 National Dolphin LX-36′ with dual slide outs ONLY WORK’S with the
    AC 110/120 volt’s for the slide out’s, either the shore line, or the gen-set is used to
    open/ or close the slide out’s Never heard of the 12-Volt’s to operate the slide out’s.

    Richard (Dick ) Walton ,Houghton
    [email protected]
    808-681-4872/ cell -808-366=8153

    In Hawaii, and enjoying the Weather-Dick