Can a 25A breaker damage a 5500w water heater?

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Rob Miller

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I recently installed a Rheem Gladiator 5500w water heater whereas the old one was a 4500w. My home was wired with 10ga wire and a 25A breaker. I saw the draw on the heater was at 22.5A and I asked the installer whether the 25A breaker should be replaced -- he didn't think it was a problem. A week later my water heater issued an alert indicating a potential problem with the control board. The breaker never tripped, so it doesn't seem there would have been too much voltage or overheating of the wires -- in my mind if the breaker were too small the only thing that would happen is it would keep tripping if the draw were too high. I called Rheem and they advised that the heater had to be installed with a 30A breaker and advised me this may void the warranty. I swapped the breaker out for a 30A and the alert cleared, and called them back and advised them that the situation had resolved, since I wanted their records to reflect that. Then a week later I got a new A114 alert indicating overheating of the panel (A114* : Safety Temperature Protection : Replace water heater). So my question is, could use of a 25A breaker where a 30A breaker is required damage the circuit board on the water heater in any way, esp. since the extra capacity is for overcurrent anyway? My feeling is they may try to avoid warrantying the unit but I don't think having the 25A breaker would have caused damage to it. Thoughts?
 

Reach4

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I agree with your assessment.

Did the 25 amp breaker trip (not that that should cause a board failure)?
 

WorthFlorida

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A circuit breaker protects the wiring, not the appliance. A 25 amp near its current rating will get warm and possible lower the voltage across circuit breaker as it heats up. Enough heat and it would trip. The water heater should have its own low voltage protection, especially the so called smart units.

Look at page 8 of the installation and it recommends 30a. It doesn't state required. The 80% rule can apply hear, that is continuous current draw should be no more than 80% of the rated breaker for longevity and to prevent false tripping. https://images.homedepot-static.com/catalog/pdfImages/c7/c7aa2c48-f3ce-43e9-838f-9182c1909c6a.pdf

Place a voltage meter at the 240 volt connection at the WH, turn up the temperature to turn on one of the heating elements and watch the voltage. If it never drops and the WH trips an error code, it's the WH problem, not your breaker.
 

Phog

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Adding my 2 cents here. If there were significant voltage drop at the breaker (sufficient to cause problems at the unit) you would see signs of this. A change in appearance of the wire insulation, melting, scorching, or at minimum discoloration. A 5% +/- variance is within the range of normal home AC service panel voltage -- not every house gets exactly 240V from the electric company transformer. So this incoming voltage range is engineered into every appliance. A 5% voltage drop across a breaker equates to something like 250W of heat being dissipated through the breaker body. You are going to see significant wire melting & scorching at that level if running for any length of time. So if you don't see any wire damage the breaker was operating perfectly fine (even if current was a little above spec) and not affecting the voltage at the water heater.
 

Reach4

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A 5% voltage drop across a breaker equates to something like 250W of heat being dissipated through the breaker body.
That would also indicate a very defective breaker. The difference in heating in a 25 amp breaker and a 30 amp breaker carrying 24 amps would be small.

However that was your point... that you agree that using the functioning 25 amp breaker would not have caused a fail other than possible extra tripping.
 

jadnashua

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AT 5500W, you're exceeding the 80% factor on a device that could be running nearly continuously with a 25A breaker, depending on use. The 80% rule would seem to apply, which, on a 25A circuit, would provide only 20A continuous (5500W would be nearly 23A). A 4500W element would be fine on a 25A circuit. 10g wire can support up to 30A, so at least you're not overstressing the wiring and breaking the code.

Long duration at near max on the breaker may mean it will fail sooner than if you were to abide by the 80% rule. The heat generated can mess with the spring temper, eventually, increasing the internal resistance, and generating more heat.
 

Rachel Bayne

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Rob... I also have the same Rheem Gladiator water heater... And after working perfectly for 3 weeks, it's dead. A114 error. (manual says replace water heater) I saw several reviews for the same Gladiator WH where people rated it 5 stars but changed their review after the control panel failed in one way or another. A plumber will be at my house any minute, and hopefully it will be a quick fix.

What is happening with your water heater now?
 
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