Tripping breaker(a)
#21
Not sure we are at root cause yet.
Thought that moving the water heater breaker up one slot changed behavior, but that isn't consistent.

Moving the water heater to an extension cord off the main panel seems to help (up and until we start putting AFCIs on that panel?).

Where did you see the notes on the water heaters triggering AFCI issues?
Navien (natural gas) tankless water heater and siemens subpanel/AFCI.


Matt
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#22
(04-08-2022, 12:49 PM)mdhills Wrote: Not sure we are at root cause yet.
Thought that moving the water heater breaker up one slot changed behavior, but that isn't consistent.

Moving the water heater to an extension cord off the main panel seems to help (up and until we start putting AFCIs on that panel?).

Where did you see the notes on the water heaters triggering AFCI issues?
Navien (natural gas) tankless water heater and siemens subpanel/AFCI.


Matt

It was on Mike Holts forum, I will see if I can locate it again.   Did you check with Navien ?   They should know how to work around.  Roly
Web Site https://forums.mikeholt.com/threads/arc-...er.102418/ If the wiring closely parallels the other circuits it can have an effect also.
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#23
Dedicated circuit from main panel didn't change behavior.
Plugging heater into surge suppressor and then into outlet seems to inhibit the trips.
Interestingly, so does plugging the heater directly into the outlet and either a surge suppressor or an extension cord into the other port of the outlet.

Next week we'll be continuing call w/ the heater mfg.  This didn't sound like something they had seen before, but apparently there are some things we can walk through to check out various modules in the system.

Matt
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#24
(04-08-2022, 07:03 PM)mdhills Wrote: Dedicated circuit from main panel didn't change behavior.
Plugging heater into surge suppressor and then into outlet seems to inhibit the trips.
Interestingly, so does plugging the heater directly into the outlet and either a surge suppressor or an extension cord into the other port of the outlet.

Next week we'll be continuing call w/ the heater mfg.  This didn't sound like something they had seen before, but apparently there are some things we can walk through to check out various modules in the system.

Matt

 It sounds like the surge suppressor is filtering out the interference from the heater that is tripping the breakers.   There is enough comments on the internet about tankless tripping the arc fault breakers that I would think the company would know.  It is not only Nivien.   Roly
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#25
While I'm sorry Matt has this issue, and hope he finds the root cause and gets everything working properly, I must say that i really enjoy these electrical threads, I learn so much from them!
Credo Elvem ipsum etiam vivere
Non impediti ratione cogitationis
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#26
Wondering where this issue is now.
Blackhat
Common decency is as rare as common sense. I figure there was only a finite amount of both made and its getting shared out among too many folks.


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#27
(04-18-2022, 01:19 PM)blackhat Wrote: Wondering where this issue is now.

So are we.   A lot of people say the best place for a arc fault breaker is under your truck tire.   Many false trips.   I would suggest keeping the old breakers just in case.  Roly
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#28
Not much clarity yet, although we're not seeing trips at the moment.

As of last update, we had the water heater on a 15A breaker from our main panel, with a WR-GFCI at the outlet.  We were still getting the AFCI breaker on the stove hood to trip when it was used and the water heater was plugged in, but we weren't seeing issues on our other afci's anymore.  If the heater was plugged into a surge suppressor, the stove hood was working, too.

Tech support for the water heater wasn't sure why other circuits could be affected; this didn't sound like it was in their troubleshooting materials.

When I replaced the receptacle at the water heater with an AFCI/GFCI, I didn't see any trips on anything.
When I replaced the receptacle with a different GFCI, the stove hood afci was still tripping.
When I put the original GFCI back on the tankless, things are not tripping.

Seems touchy, so will be continuing to monitor.
My concern would be if there is some problem with the controller on the tankless generating high conducted emissions that would be best caught when under warranty.

Putting the tankless onto an AFCI breaker (and seeing if that trips) might help to confirm origin.
(or getting an alternate tankless unit and seeing if that trips the other cricuits too)

Matt
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#29
I would suggest contacting the arc fault breaker manufacturer ,  they may be able to help.      As I understand the breakers are looking at a interference pattern on the electric that it thinks is a fault.  Not that there is a fault with the heater but just a similar pattern.   Roly
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#30
9pm: that didn't stay fixed long. Fan hood was tripping the breaker again this evening.

4pm: May have resolved things today by bonding the water and gas pipes at the tankless heater.
This was after a fair bit of head scratching with another electrician.
(we had bonded at our old heater, but that had been partially undone when the heater was removed and then not redone for the tankless in its new location)


Matt
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