water heater trips main AC breaker

[fulvio]

Ever since my last cruise, I've been having some AC problems.  I think I have narrowed them all down to a bad AC main breaker.  The breaker I'm talking about is the push button on the instrument panel, which is rated for 30 A, and disconnects all AC from the boat's circuits.  I thought I had a problem with the water heater, because it was the only thing to consistently trip the breaker, within 2 to 20 minutes whenever I turned it on.  I inspected all wires and connections (except those in the heater, see below) and could not find anything wrong.  The main breaker does feel moderately hot to the touch right after it trips.  Finally, I measured the current drawn by the water heater alone (11.5 A max) and by the entire house (not much more than 12 A, with nothing significant running), and I concluded that the breaker really should not trip at such a low draw.  So I'm going to try replacing the breaker, which by now should be 16 years old.  Any comments?

The other question I have is:  how do you access the electrical connections inside the water heater?  I have the factory-installed Seaward, and I opened the small cover where the wire goes in.  However, except for the ground (green) wire and the reset button, I can not see any other connections directly.  The white and black wire go in further, behind a sort of thick cardboard cover, and I don't see how to get to their connections without opening up the whole heater.

[Jim Price]

First on the breaker.  Your panel was made by Seward also and you can call them on the AC breaker.  Second comment, I experienced similar problems in past and due to (in my opinion) unreliability of push button breakers, I replace the entire panel with upgrade from Seward.  The cost of replacing old push button breakers is not small and you can buy current style cheaply anywhere.

Water heater.  I rebuilt mine couple of years ago when fitting on tank failed and started leaking.  Again worked with Seward for replacement parts.  The wiring you are referring to is behind the cardboard cover but you can access all the connections by carefully removing the cover.  I think there may be couple of screws you have to locate.  It is possible that your heating element may be old and corroded thus causing excess power drain and tripping breaker.  The heating element can be bought at Home Depot for about $9.00.  DON"T go bigger in wattage just to heat your water faster.  IT WILL  NOT WORK, unless you change out the breaker to higher capacity and that is asking for a electrical disaster.  Stick with like size replacements. 

Final note, if your heater is old, you may have to remove the entire tank from the boat to get the element out.  I had to put my whole rig in a large vise to break the corrosion seal.  and that was after all sorts of penetrating oils used.  Remember, it is plumbing and it seizes over time.

[Ron Hill]

Fulvio : If it takes some time (2-20minutes!!) to trip it shouldn't be the water heater.  I'd guess it's the breaker unless you have the WRONG size water heater breaker!!!!
 
My data says that the MKI and the MKII  115v hot water heater breaker should be a separate 20amp, not the 30amp as you have mentioned.  The separate WH breaker only shuts on/off - ONLY the WH, not all AC on board !?!
 
Better check that out before you do anything.   

[Stu Jackson]

Fulvio

Ron has a point.  Our main breaker (30A) is a toggle.  Just below it is a pushbutton for the heater, which the electrical distribution portion of the manual, I recall, says it is LESS than the main 30A breaker.

If I remember, Ron, that Fulvio may have been one of those skippers who replaced their 6 gallon heater with an 11 gallon one.  I would guess that the heater cores and amperage draws would be the same:  more water - just longer to heat more water.

[fulvio]

Right, what's tripping is the main AC breaker, not the WH one.  It stands to reason that the WH breaker would be less than the house breaker.  So if the weaker link in the chain doesn't break, it must mean that the supposedly stronger link is actually at fault.

On my panel, the AC section is at the bottom.  On the left side, there are two breakers/switches:  one (on bottom) for the water heater, the other (on top) for the outlets.  Further to the right, by itself, there is the pushbutton switch/breaker for the entire house AC circuit.  That's the one that's tripping.  I checked again, it's a 30 A, and it is even embossed on the front of the panel (but it says so also on the body of the breaker).

No, I have not replaced the original water heater, so I still have the 5.5 gallon one.

[Craig Illman]

I'd suspect the breaker itself. Either, as suggested above, contact Seaward about a replacement or go down to Fisheries Supply and purchase a toggle. When I replaced by shore charger a few weeks ago, I replaced the push button breaker with a toggle. It took me a couple hours from not having the proper tools to enlarge the hole.

A good source for boat mechanical locally is Steve Sands, Sands Marine 206-972-3555.

Craig Illman

[fulvio]

The breaker it was.  I replaced it with a Blue Seas toggle breaker from Fisheries, and now all is good.  I, too, had to enlarge the hole and drill two new holes for the screws.

My only misgiving is that the toggle seems so much easier to flip off inadvertently.