Water Heater tripping breaker

T

Tim Fila

Well-Known Member
Aug 24, 2020
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First season with the 52DB. When we bought the boat, the Water Heater did not work. We replaced the thermostat and the heating element. It worked great until this passed weekend. Now it keeps tripping the breaker on the main panel. Should I replace the element and the thermostat again, or just the element?

Thanks,
Tim
 
It's usually the element. But I'm surprised it happened so quick if you just replaced it (them). They should last for years. But they (one of both) could be defective. Any corrosion on any wire ends or any kinks in the wires?
 
Im surprised as well!

No corrosion or kinks (except mine).

Tim
 
We purchased the boat in October. It was for sale for quite a long time. I'm certain at some point, the water heater was turned on while it didn't have any water in the tank. When we did the survey, it did not work. So, we replaced both at that time, just to start fresh.

I will dig into it this weekend to see if I can get continuity on the element.

Tim
 
assuming you replaced with the right size element? what make/model water heater do you have? most elements are 1500watts @ 120v. wondering if your 52DB provides 220v to the water heater? isotherm water heaters have a 2000watt/220v heater on some of their models. could simply be the wrong size element, or even a weak breaker - given the PO toasted the element before.

should not be the thermostat, as that simply turns the element on/off.

how long does it take to trip the breaker once you turn the heater on? right away, or after like 20-30min?
 
I googled the model number to get the correct element.

It is a 91581. 1500watt @ 220v

I'm hoping it was a defective element.
 
Tim Fila said:
I googled the model number to get the correct element.

It is a 91581. 1500watt @ 220v

I'm hoping it was a defective element.
Click to expand...

current (amps) draw at 220v is incredibly low (for a heating element) - 6.8amps.

if it was a defective element i would expect it to trip the breaker rather quickly (or instantaneously). when does it trip?

do you have a multimeter with a clamp on current meter?

whats the actual model of the water heater?
 
markrsimon said:
current (amps) draw at 220v is incredibly low (for a heating element) - 6.8amps.

if it was a defective element i would expect it to trip the breaker rather quickly (or instantaneously). when does it trip?

do you have a multimeter with a clamp on current meter?

whats the actual model of the water heater?
Click to expand...

Great question on when... It's not instantly. I've not narrowed it down, other than it tripped when my wife was in the shower. I reset it and it tripped again at some point.

I do not. Just a Fluke 115.

Attwood E20-220

Tim
 
markrsimon said:
current (amps) draw at 220v is incredibly low (for a heating element) - 6.8amps.
Click to expand...
Not so low if it is, in fact, a 220V heating element. That equates to 1500 watts.

@Tim Fila, as long as you have an ohm meter on your Fluke, disconnect the wires to the heating element and check not only across the contacts (should be around 32 ohms) but, more importantly, check from either contact to ground. Anything less than infinity shows that there's a short to ground. It's possible you have a heating element suffering from "infant mortality". This usually comes about either from old age, or from being powered-up without having been filled with water first. Don't ask me how I know...
 
there seems to be alot of confusion on what the right part number is - based off of my google searches.

there is a 91580 (120v) and a 91851 (220v) with some online sites cross referencing the two together. they switch the 58 and 85 way too often.

my guess is you have a 1500w 110v element and your using it in a 220v application - which would trip the breaker.

best suggestion is to call atwood and get the real story on what part number is correct.
 
I did get it on amazon....who know what the seller sent.

Although it had been working great for several months...

Tim
 
owners manual for your boat shows a 6amp breaker for the water heater @220v which equates to 1320watts, which is a bit less than the 1500watt element.

do we know what the original water heater make/model is/was?
 
markrsimon said:
owners manual for your boat shows a 6amp breaker for the water heater @220v which equates to 1320watts, which is a bit less than the 1500watt element.

do we know what the original water heater make/model is/was?
Click to expand...

Attwood E20-220
 
So, 220 volt unit confirmed. The fact that it will run for a bit then trip makes me think you're in need of a new breaker. They can and do go bad. However, as @markrsimon mentioned, the schematic calls for a 6 amp breaker. Looking back through your previous posts, I don't see where the breaker's actual rating is listed. You'd need a larger circuit breaker to support the 1500 watts/6.8 amps that the heater needs, so I wonder if someone didn't swap a smaller heater for the current unit somewhere in the past. You might be able to just swap in the larger breaker, but the associated wiring would have to be heavy enough to handle that load. I'd be very leery of upping the breaker without knowing more about the wire size. If it turns out to be insufficient to properly handle the load, there's the possibility of installing a lower-rated heating element. It would mean slower heating, but it sure beats an electrical fire!
 
The water heater circuit breaker is a 10 Amp for the 52DB.
First check the wiring at and around the heater to make sure the insulation is good and the wire isn't shorting to ground somehow.
Then disconnect the wiring from the heating element and measure the resistance of the heater itself. There should be no continuity (infinity resistance as said earlier) between either of the wire connection posts and the metal flange that mounts to the heater tank. Assuming no shorts to ground then measure across the two posts. For a 220/240 Volt 1500 watt element the resistance should be between 32 and 39 ohms. For a 110/120 volt 1500 watt element the resistance should be between 8 and 9.6 ohms.
A 220/240 volt 1500 watt element will demand between 6 and 7 amps
A 110/120 volt 1500 watt element will demand between 12 and 14 amps.
That circuit breaker is a magnetic/hydraulic type and may not instantly trip if the current is higher than rated. You will probably have some time before it trips if you have the 120 volt heating element in the water heater. If these checks reveal the wiring is good and the heating element is correct then I agree the circuit breaker may be going south...
Here is a typical trip curve for these circuit breakers -
Toggle_CB.jpg
 
Last edited:
sorry - I skimmed through the manual a bit too fast. the large numbers overlaid on the breakers in the manual are not breaker ratings - they reference the item number in the parts table below the drawing. awesome description/diagnostic info by ttmott above.
 
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