Forum Discussion

kemer's avatar
kemer
Explorer
Mar 04, 2019

Automatic Transfer Switch Failure

Has anyone had problems with their Automatic transfer switch shorting out? I have a 2014 Winnebago with a Progressive Dynamics transfer switch. On Saturday, we had both AC units running and the microwave going which we've done plenty of times before. All of a sudden we heard a "pop" like a power surge or something. Went out and looked under cabinet and it was smoking...so I unplugged shore power. Once everything cooled down I looked at the box and something shorted out and burned a bunch of wires. Got a repair guy coming out shortly to fix the issue. Some people around me said that sometimes the screws that hold wires will get loose causing more resistance and cause wires to heat up. Not sure if that was the case....

Comments welcomed....

Thanks
Class A

9 Replies

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  • YC_1's avatar
    YC_1
    Nomad
    Mar 05, 2019
    Ditto:
    Ditto what you ask?

    Every poster here is dead on.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Mar 05, 2019
    If I had to guess I'd say you did not have a short. you had an open (Opposite of a short)

    I have not had that problem with an ATS but I have with other parts of the electrical system. It has a cause.. and I'll make a non-joke here

    Many RVers have a few screws loose (Now I know lots of folks who agree with that but not in the way I mean)

    If the screws holding the wires are loose. arcing can happen and high resistance connections. as the resistance goes up the amount of heat in the connection increases. and when it is hot enough the wire melts and .. Well you saw that.
  • Sam_Spade's avatar
    Sam_Spade
    Explorer
    Mar 04, 2019
    Yes. Almost those exact circumstances.

    As part of the repair, I had them eliminate the "automatic transfer switch" in favor of a "manual" outlet for the generator. That's how it is done on many C's.

    Now **I** am the transfer switch !! :B
  • garyemunson's avatar
    garyemunson
    Explorer II
    Mar 04, 2019
    X2 on the loose terminals. Transfer switches in RVs are notorious for starting to buzz as they get older because road dust and dirt get between the metal armatures preventing them from sealing up tight. The resulting vibration loosens the terminal screws and soon after that the burning starts. Good annual maintenance should include at least tightening the terminal screws and even better taking the relay apart to clean the moving parts. Alway make sure you are unplugged from shore power, the generator is not set for autostart, and the battery switch is off the make sure your inverter doesn't start making AC!
  • wolfe10's avatar
    wolfe10
    Explorer
    Mar 04, 2019
    Yes, loose connection is by far the number 1 cause of ATS failure.

    A good reason to torque ALL 120 VAC ELECTRICAL CONNECTIONS ONCE A YEAR-- ATS and 120 VAC breaker box(s).
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Mar 04, 2019
    Remember 2 things

    *Installation at factory is done QUICKLY....no time to torgue wire set-screws/terminals

    *RVs traveling are mobile earthquakes

    EVERY electrical connection should be checked/re-tightened at least yearly
    That includes Main AC Panel, DC Panel, Battery cables etc

    Loose connections cause High Resistance which leads to heat which can result in melted wire/insulation and even FIRE


    Edited for gramma/sp
  • Community Alumni's avatar
    Community Alumni
    Mar 04, 2019
    I had a similar situation happen during a cross country trip about 10 years ago in a new motorhome. Wires and switched box fried and had to be replaced.
  • DrewE's avatar
    DrewE
    Explorer II
    Mar 04, 2019
    It's hard saying not knowing, of course, but a loose connection getting hot is one reasonable and not unlikely explanation for what you saw.

    Although colloquially "shorting out" is sometimes used to mean almost any electrical difficulty, a loose connection heating up has nothing to do with an actual short circuit. A short in the transfer switch would cause the pedestal breaker to more or less immediately trip from the very high current that flows.

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