Main Breaker

My 1983 Mainship 34 III is on the hard behind my warehouse for the winter. During the season, when I switched over to shore power, the main breaker would trip. Easily reset, go on with my day. When I put it up on stands, I plugged in to an exterior GFI on a 20 amp circuit and leave the battery charger on until I had time to winterize and disconnect the battery. Every time I came back to the boat GFI would trip or the main breaker on the boat would trip. Is my main breaker done for and in need of replacement? Can I even get one to fit the original Mainship panel? Is it time for some electrical upgrades seeing that there are devices on the boat that don't even have circuit protection, never mind a means to kill the power to them.

Well, you just said a mouthful. I can't explain why the main breaker trips at the dock- overloaded, bad, etc.

I can explain why the GFCI outlet trips. Boats are inherently wet, duh!! The moisture creates a path to the protective ground and the GFCI trips. There is little you can do about it. Even new boats do this. So don't plug into a GFCI protected outlet.

And do you have unprotected devices as you said or unprotected circuits, ie wire? Fix the circuits before you fry yourself or burn up your boat. Most devices either have their own protection like a thermal overload or don't need it.

David

Ok, didn't think the wet thing worked itself into the equation while on the hard, so I guess I deserve the duh. Nothing 120 volt unprotected, but a few 12 volt things are wired in and there is no switch to turn off the device. I hate the way all the wiring is run on a boat, such a nightmare to follow and always the abandoned wires to clutter things up.

Is there a chance your boat's main breaker is also a GFCI breaker? Connecting two of these on the same circuit can cause problems.

I would find away to get the extra GFCI device out of the circuit and see what happens. You might have to run a cord out a window of the building to test this.

As for replacing the boat's main breaker, disconnect the shorepower cord, then open up the panel. Tag the wires and take few digital photos, then remove it and look for markings. You might want to just disconnect it and take it to a well stocked marine store.

Now that you bring it up Ron, all my outlets are GFI and they are all on the same circuit. I am keeping the outlet circuit on to run power tools and lights. I thought you can only put one GFI on a circuit. Later in the season I plugged in a heater and one GFI tripped and I had to go to every GFI to see which one tripped. I think it's time to cut it down to one. Which do I keep, the one closest to the panel? Do they make a GFI breaker for marine panels? Also, there are 3 wall sconce/lamps in my saloon and they are wired into the outlet circuit with what appears to be lamp cord. The winter projects just keep adding up....

Greetings,
Mr. ss. I agree with Mr. r regarding disconnection of shore power (post #4) and I will add, IF you have an inverter, turn that off as well while monkeying with your electrical.

slowandsteady said:

Now that you bring it up Ron, all my outlets are GFI and they are all on the same circuit. I am keeping the outlet circuit on to run power tools and lights. I thought you can only put one GFI on a circuit. Later in the season I plugged in a heater and one GFI tripped and I had to go to every GFI to see which one tripped. I think it's time to cut it down to one. Which do I keep, the one closest to the panel? Do they make a GFI breaker for marine panels? Also, there are 3 wall sconce/lamps in my saloon and they are wired into the outlet circuit with what appears to be lamp cord. The winter projects just keep adding up....

Click to expand...

Assuming all your outlets are on one circuit, install the GFCI receptacle as the first one and feed the others from it. Study the installation diagram for how to wire it this way.

If you have more than one circuit, do this for each circuit.

Many of the simple outlet testers available at home centers have a button to check the GFCI function so you might want to buy one for the boat just to check from time to time.

slowandsteady said:

........... Also, there are 3 wall sconce/lamps in my saloon and they are wired into the outlet circuit with what appears to be lamp cord. The winter projects just keep adding up....

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Wiring something permanently with lamp cord is a definite no-no. You have some work to do.

There may be more to it than a bad breaker. The problem only occurring using shore power is a clue. I have uncovered a couple examples of loose connections and burned out shore power inlets with the same symptoms.

You need to start at your inlet fitting(s). Remove them from the hull and check the back sides for loose and melted connections especially if they are discolored (overheated). Check all the connections on your transfer switch. Put eyes on the entire shore side wiring between the inlet fitting and transfer switch. It would seem your generator side is OK.

Surveyed a catamaran that had nuisance trips. Found burned wires on the back of the inlet fitting. Surveyed a trawler that had nuisance trips. Tapped a neutral wire on the ship/shore switch and it fell out of its ring connector. You are being given clues. Both were vessels that had been in service for years.

slowandsteady said:

My 1983 Mainship 34 III is on the hard behind my warehouse for the winter. During the season, when I switched over to shore power, the main breaker would trip. Easily reset, go on with my day. When I put it up on stands, I plugged in to an exterior GFI on a 20 amp circuit and leave the battery charger on until I had time to winterize and disconnect the battery. Every time I came back to the boat GFI would trip or the main breaker on the boat would trip. Is my main breaker done for and in need of replacement? Can I even get one to fit the original Mainship panel? Is it time for some electrical upgrades seeing that there are devices on the boat that don't even have circuit protection, never mind a means to kill the power to them.

Click to expand...

GFCIs do go bad sometimes...


-Chris

I had a similar problem on a previous boat. The problem was the galvanic isolator. This only occurred when on shore, never while in the water. The manufacturer recommended that I put the system into test mode as I connected shore power. This seemed to fix the problem.

No galvanic isolated on my boat, so I can rule that out. Took a look inside the panel and the ground and neutral bars were totally separate, nothing to see there either. Next time I'll check the shore power plug and cord. Since I disconnected the batteries and shut down the battery charger the main breaker hasn't tripped. After I opened up the main panel I found a little sticker inside that said "Mainship MS1". Mainship must have bought a bunch of these panels and kept using them on later models.

Good on you for taking the time to check those items. It may not turn up a problem and if not you will have some piece of mind knowing they have been checked. If something later does go wrong you will have a reference point.

slowandsteady said:

No galvanic isolated on my boat, so I can rule that out. ............

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I would add one after you get any other problems sorted out. They are pretty important if you have shore power on your boat.

Catalog Frame

Click on Galvanic Isolator and then the button that describes what they do.