While living on our boat last January we had quite a scare. Suddenly the cabin
filled with smoke. We were in a slip on shore power
. Sherry and the dog got on the dock
right away, I pulled the shore power plug
, turned batteries off. Then opened the hatches and ports
. The smoke was coming from under the aft berth where our Seaward water
heater was installed. Fortunately it is quite accessible, I had it out of the boat and onto the dock
quite quickly. It was still smoking. The smoke quickly cleared in the cabin
and fortunately did not leave any residual smell. We were lucky that we were on the boat when this occurred. We now only turn the hot water
tank on when it is needed, and never leave it on when we are not on the boat.
I opened the heater to investigate the problem and photographed what I found. It appears the black wire got red hot, melted all the insulation
off of it and burned all the insulating paper. Had I not been on board to turn the power off I don't know how much further this may have progressed. The thermostat and high temp did not open because the water did not over heat and the heater did not exceed the breaker trip current
. I think maybe the black wire was corroded and turned into a high resistance. The water heater was built in 2003. The tank was installed in a very dry location, showed no corrosion
on the outer case or inner aluminum
The heater was factory installed running on a 15 A breaker, 14/3 marine
wire from the panel. The black wire began to melt the plastic after it passed into the insulated area of the heater. It terminated with crimped ring terminals at the high temp shut off, then the thermostat and finally at the heating
element. The white return wire going up from the heating
element appears to only have been damaged by the heat generated by the black wire. The element is rated at 1500W and measured about 10 ohms, I did not measure any leakage to ground in the element.
I contacted Seaward
, reported the problem, sent them the photographs and also the electrical
components. They promised to submit the parts
to a lab for analysis of the fault, and let me know the results. So far I've heard nothing more. I don't know why this happened. I'm not trying to say Seaward did anything wrong or it is a bad design. We replaced it with another Seaward water heater. I do want to advise others about the potential hazard of leaving the water heater on when you are away from the vessel or asleep.
(I also posted this here