Separate Breaker Trips when Tankless Water Heater Runs

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Old 06-11-18, 08:36 PM
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Separate Breaker Trips when Tankless Water Heater Runs

Hello,

I have a whole-house electric tankless water heater in my home which is powered by 3 40A breakers. For the past few months, every so often, my living room circuit, powered by a 20A AFCI breaker, will trip whenever the hot water is turned on. No other breaker in the house has tripped, and so far, no other heavy load appliance trips the breaker (heater, oven, dryer, etc.).

I've checked and re-checked the wiring. There is nothing crossed and the circuits are isolated from one another. I can see no loose neutrals or grounds at the panel, but I have yet to check each receptacle and switch on the living room circuit. Is it possible that a loose connection in one these would cause the breaker to trip when the there is a heavy load on the whole system like that of the tankless water heater? Could it be a bad breaker on the living room circuit?

Any suggestions are greatly appreciated.

Thanks,
Peter
 

Last edited by Peteryoungblood; 06-11-18 at 09:04 PM.
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Old 06-11-18, 08:54 PM
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Welcome to the forums.

Are you sure it's a GFI breaker. Could it be an arc fault type breaker ?
 
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Old 06-11-18, 09:04 PM
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Sorry for the mistake! I meant AFCI. I'll edit the original post accordingly.
 
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Old 06-11-18, 10:14 PM
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No problem..... just makes more sense.

I doubt you'll find any physical problem. My thoughts are that the some or all of the water heater lines are parallel to the circuit that is tripping. When the WH starts up there is a spike created on one of the power lines and it's being inductively picked up in the tripping circuit.

Post the make an model of the water heater. There may be an issue that can be resolved at that end.

If you have more than one AFCI breakers you could try swapping a different one place of the tripping one. I'd even try replacing the tripping breaker.
 
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Old 06-12-18, 06:34 AM
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Thanks. The home run to the living room does run parallel along the water heater wires for a short distance, so your idea makes good sense. I just thought the wire insulation would have been enough to prevent the level of induction that would cause the breaker to go to fault.

The water heater is an EcoSmart ECO24. I've also had issues with it making the lights in the house flicker while running, which the company says could be caused by some malfunction in the circuit board of the unit.

I've thought about swapping breakers. The problem is the tripping is not easily repeatable, and I'd hate to buy a new breaker without knowing for certain whether the breaker is bad, since those AFCI breakers aren't cheap.
 
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Old 06-26-18, 07:51 PM
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I've swapped out the offending breaker with two other AFCI's I have in the system and both exhibit the same tripping when wire up to the living room circuit. I've tried to force the trip by turning on my WH, dyer, over, A/C, and drawing juice from almost every outlet in my living room circuit, but I can't do it. It seems to only trip sometimes, and only when the hot water is running, but it doesn't seem repeatable.

I did notice that the breaker in sits a little funny on the neutral bar (I'm suing the AFCI breaker without the pigtail). Could this have anything to do with it? If so, I can get one with a pigtail and solve that issue. The problem is that because the trip is so seemingly random, I might think its fixed for a few weeks until the next trip occurs.

Any further ideas or advice would be greatly appreciated.
 
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Old 06-27-18, 10:30 AM
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I've also had issues with it making the lights in the house flicker while running, which the company says could be caused by some malfunction in the circuit board of the unit.

Flickering or dimming? Flickering is usually indicative of a loose connection while slight dimming is somewhat typical of when a heavy load comes on line.
 
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Old 06-27-18, 03:07 PM
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Flickering. But the thing is that all the lights in the house flicker when the water heater runs.
 
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Old 06-28-18, 08:56 AM
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Since ALL the lights in the house are flickering and the heavy load is 240 volt, I'd start by checking for a loose or bad connection at the service panel and meter socket. Look closely at the main breaker. I'd also check voltages at each of these points too. What kind of panel do you have and how old is it? Aluminum or copper bus panel? What type of lights are these? Are they CFLs, LEDs, incandescent, halogen........? Depending on what you find, you may also need help from your electric utility.
 
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Old 06-29-18, 08:24 AM
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I'll check it out, thanks. The panel is only about 2 and a half years old. It's a HomeLine panel with aluminum bus bars. Light are of different types, some LEDs some incandescent. LEDs seem to flicker more.

Would a loose connected at the panel also cause the tripping problem? I've checked and rechecked the connections to the tripping breaker and the WH, but the only thing that seems a little loose is how the AFCI breaker sits on the neutral bar. It snaps on well enough, but the breaker seems to wiggle more than the others.
 
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Old 06-29-18, 12:03 PM
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The tankless heater is adding a tremendous load on the panel which could be lowering the voltage substantially. Was the power company informed when you added all this new load to the service? I'd check the voltage at the main breaker while the unit is running. Some LED lamps are sensitive to low voltage so that could be part of the problem. I'd also think that since ALL Lights have some flicker that there is a possibility of a poor or loose neutral connection. As far as the AFCI breaker tripping, I think PJ hit that one on the head. You may have to try some relocating of some circuits.
 
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Old 06-29-18, 02:07 PM
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Thanks again. By "relocating" some circuits, do you mean simply changing the location of the breaker in the panel, or re-routing the home run farther from the WH wires?
 
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Old 06-29-18, 02:53 PM
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Either... or. It's going to be experimental. I've been reading about the Ecosmart units and they seem to be having problems due to the switching system they're using. Some people are having noise issues due to the switching semiconductors.
 
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Old 06-29-18, 06:30 PM
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What about these questions?




Was the power company informed when you added all this new load to the service?


What kind of panel do you have and how old is it?

By relocating circuits I meant re-routing of the home runs.
 
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Old 06-30-18, 12:24 PM
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I've had the Tankless Water Heater since the service to the house was turned on, so its not a new load. I asked the power company about the flickering and they assured me that my service should be able to handle the load of the water heater and also that the flickering was most likely due to the unit itself and not any issue with the power.

I have a HomeLine panel that's only a couple years old.
 
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Old 07-01-18, 10:42 AM
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I've had the Tankless Water Heater since the service to the house was turned on, so its not a new load.

You missed the point. Most power companies size their transformers and service drops by calculated load and not to the size of your service. If they had known you were adding this big load they may have increased the size of the transformer and drop to your house. You could just be getting extremely low voltage when the water heater comes on. Just because you have power doesn't mean you have the correct voltage. Have you checked the voltage while the unit was running?


I have a HomeLine panel that's only a couple years old.

It's a builder grade, but should be adequate. The possibility does exist though that the main breaker could be bad. It's not that uncommon for Homeline 100 amp breakers to fail.
 
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Old 07-04-18, 05:53 AM
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I haven't checked the voltage. I'll do that to be sure. But, as I said, I directly asked the power company about the WH causing flickering and they told me that my setup, including the transformer they have installed, should be adequate for the load. Of course, they could have just been telling that to get me off their back. They haven't been the most helpful folks to deal with.

To be clear, I have 200 A service.

In any case, I haven't had a trip in a few days after moving the breaker to another spot in the panel. One other thing I did notice before moving it, though, is that it almost always would trip in the late afternoon. That's as close to repeatable as the problem became. At around 5 pm, if I turned on the shower while my living room circuit was on an drawing some juice, it tripped every time. The only thing I could think of is that the heat in the attic at that time of day (I live in south Louisiana) was making the electrical noise more pronounced and the induction that PJmax spoke about reached the critical threshold to trip the breaker.

Thanks again for the help. It is very much appreciated.
 
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Old 06-10-20, 12:33 PM
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Peteryoungblood,
I have the exact same problem that you had. living room breaker tripping after Ecosmart tankless water heater turns on, the only difference is:
  • living room breaker is a gfci/afci combination
  • Ecosmart WH model is 27 (not 24)
Did you find your problem?
If so, what was the problem, I would like to start there.

Thank you!
 
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Old 06-15-20, 07:54 AM
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Mvelez,

I haven't had another trip since my last post. I did two things. First, I switched my living room AFCI breaker to another space in the panel. In my case, I just swapped my living room and office breakers, since they were right next to one another. Second, I bought a new surge protector for the entertainment/computer setup that was on the living room breaker, as I had read that some surge protectors can act up on AFCI circuits.

I believe the first thing I did is actually the real fix in my case. Have you tried that?

 
 

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