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Fuse between inverter and panel blew, what should that tell me?

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  • Fuse between inverter and panel blew, what should that tell me?

    Had a 8kw system installed early this year. Has a SolarEdge 7600HDWave inverter connected to the electric panel with a disconnect box with a fuse (or maybe a fusible link?) between them. Yesterday afternoon the system stopped producing power and when I inspected it today I found the fuse box plastic insert deformed from the heat of that link failing. Breaker never tripped. I switched off the system at the breaker and contacted my installer.

    Why would the fuse melt before the breaker tripped? What should the installer inspect while replacing the failed part to reduce the chance of it happening again?


  • #2
    Originally posted by so_cal_burbs View Post
    Why would the fuse melt before the breaker tripped?
    Fault between fuse and breaker.
    Incorrectly rated fuse or breaker.
    Faulty fuse.


    • #3
      When Fuses melt their holders:
      Improper install
      Cheap ass holder w/out enough spring tension to make solid contact to fuse, even milliohms of resistance, with enough amps, will generate a lot of heat.

      8Kw @ 240Vac = 33A x .1V 3.3w of heat, with no heat sink other than the wires, it has 5 hours to heat up and get melty like a grill cheese sandwich.
      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A



      • #4
        I agree with Mike. If the fuse holder fails from heat that is usually a poor or loose wire connection.

        Time to break out the IR camera. That will find a poor connection real fast.


        • #5
          Thank you for the replies, I really have learned a ton from those that post here from initial research through today.

          Glad to read the opinions that it is most likely a simple fix. Installer is coming out later this week to replace the whole fuse box. If it fails again I'll update this thread.