Multiplus tripping breaker

[rmjohns]

Have any of you folks that installed a Multiplus had issues with them tripping breakers? I just installed the MP 12/3000 and it works fine in inverter mode. When I plug the shore power in and turn the MP to either on or charge, the "Main On" LED flashes for a few seconds and then the breaker on the dock trips.  So either it's pulling more than 30 amps or there's something going on with a ground fault.  Curious if anyone had anything similar, maybe the way the Catalina AC system is wired causes issues, ie the neutral and ground are tied together? Not sure why those issues might not present themselves prior to the MP install.

And oddly, it doesn't trip the 30 amp breaker on the boat, though maybe that has a different GFI setup.

I only had a few minutes to try it last weekend after running the wiring, so I'll be back down this weekend investigating. Any suggestions on things to look for?

Thanks,
Rob

[waughoo]

I would vote for a ground fault.  You can try turning off all the breakers on the 120v panel and letting the multi sync the 120v phase to the dock and close the relay.  Once the relay is closed, start turning on breakers.   The other thing to check is that the multi should be the first stop from the line in at the boat's shore power plug (after a breaker near the plug).  Having the power going to the panel breaker first can set you up for other possible wiring ground faults that will trip the dock's elci breaker.

[rmjohns]

Thanks for the feedback Alex. I do have a the shore power coming straight to the MP from the shore power breaker, though there is a galavanic isolator on the ground.  Do you have the ability to bypass the MP and connect the AC in to the AC out in your setup? Not sure if that's a worthwhile addition or not.

For the startup, start with the relay open. Is there an indication the MP has synced?

Thanks,
Rob.

[waughoo]

The relay is part of the MP.  When it is inverting, I picks its on phase for the 60 cycles.  When you connect the shore power, it detects that and adjusts its inverted AC to match the phase of the connected AC.  This is all automatic.

Based on you having a mk2, I suspect you likely have the braker in the aft laz right after the shore power connection.  What I would next suggest, would be to turn off the boat's 120v breaker at the nav station along with all the other 120v breakers.  If you can plug the boat into shore power and the MP will sync its 120v phase to shore and then close its relay without the dock breaker tripping, that should mean the issue is at the panel.  Adding in additional breakers will help sort out where to look for an issue.

[rmjohns]

Thanks Alex. Turns out my issue was that at some point in the boats past, a whole separate 30amp service was added for the 16K Aircon. I normally run a splitter on the shore power cord and plug both outlets on the stern of the boat into a single 30amp service on the dock.

Somewhere in the AirCon circuit, they must have tied the neutral into the main circuit neutral and that was tripping the Multiplus. Once I flipped the breaker off for the AirCon circuit, the MP was happy, though it does buzz ever so slightly.

Since I know the Aircon and the main circuit run fine off 30 amps, I'm considering merging those 2 circuits so the AirCon comes after the MP in the main circuit. That way when I run on the Honda 2200i, the MP can help boost the start for the AirCon.

Thanks,
Rob

[waughoo]

Glad to hear you got it sorted out!