First time using hot water heater, and it blew the breaker at the house (dock)

[barryg]

I've owned my boat (2005 320 Sundancer) for about 3 years now and have never had to use the hot water heater; in fact the original sticker is still covering the breaker, but since I'm heading over to the Bahamas next week, I figured I'd test it out...

I have plenty of water in the tanks, and since the boat is behind my house in the water, I have the shore power hooked up to a GFI outlet.. I turned on the water and put the breaker for the water heater to on, and in about 30 seconds the power went out on the boat, and the GFI was tripped. So my question is...

What's the proper way to use the hot water heater.. Will it work from shore power, and if so, why did it trip the breaker?

Any help would be appreciated.

Barry

 

[Frozen]

did the breaker on the boat trip or did the GFI trip?

 

[barryg]

I think the GFI tripped as all power went off on the boat.

 

[tobnpr]

First, assuming you have a genset, switch to gen power and try it again. That'll isolate the problem as being on, or off (shorepower) the boat.

I, too, have my boat's shore power from a GFI receptacle next to the pool pump...it's a 20 amp GFI. If you have a 15 amp GFI, or if it's been tripped a number of times, the power draw of the heater may be too much for the circuit...was there anything else (on the AC side) turned on at the same time? Verify the heater's power draw with the amp meter at the panel (no other AC draw) and confirm it doesn't exceed 15 amps. If it doesn't, and the breaker continues to trip with no other AC loads, replace the GFI.



Remote possibility, but I'll mention it...
Are you sure the heater was filled at the time you turned it on? If you turn on the heater when it's dry, you'll fry the element.

 

[Frozen]

i think its the GFI. If the GFI is 15amp or even 20amp and you have a decent amount of cable between the GFI and boat thats a big potentially for voltage/amp drop and could def trip the GFI. Like tobnpr said if you have a genny try it running of the genny. A hot water heat and use quite a bit of power.

 

[barryg]

Thanks for your help.. How do you make sure it's filled? Doesn't it fill automatically when there's water in the tank and the pump is on?