I'm dealing with a frustrating issue where my 3-element tankless water heater keeps tripping the breaker. Each heater element is connected to its own 40A breaker, but one of those breakers also powers the control board. The heater elements operate at 240V/9000W. After about 5 minutes in the shower, the breaker that controls the board trips. I've tested all three breakers, and they measure around 7 Ohms, which seems normal for my setup. Interestingly, the breaker doesn't trip when I use the dishwasher, washing machine, or any faucets. Given that the elements appear to be fine, what else should I check before I start removing them?
2 Answers
Are your breakers GFCI or just standard ones? Sometimes GFCI breakers can trip unexpectedly if there's a slight fault or water interaction, whereas regular breakers won't do that.
Have you thought about relocating the control board to one of the other breakers? That could help narrow down whether the problem is with the board itself or the breaker. It might be a quick way to troubleshoot without pulling everything apart.
I don't think I can just move the board alone. It seems like the power passes through the element first before reaching the board. But if I move both, it might show if the issue is with the breaker.
They're normal breakers, not GFCI.