Siemens CAFCI Tripping From Other Circuits and Cellphones

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AAR

AAR

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Washington
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01 Journeyman Electrician - Electrical Administrator
I have been troubleshooting a house that was completely rewired this year. What I have discovered about this tripping issue has finally taken me to an area that I don't know what else I could do to mitigate this.

This is 1 Siemens 20A CAFCI Plug on neutral circuit breaker, feeding 10 receptacles in the living room.

I have replaced the breaker with a new one which did slow down the tripping to around 3 times a day. I noticed the code on the first one was A00 and the replacement is A03.

I have replaced all receptacles in the room with new 20A Leviton TR receptacles, verified all wiring and even tape wrapped receptacle for good measure.

I have removed all connected devices and Meggered circuit at 500V L-N L-G & G-N, all maxing out the meter at 500 Megaohms.

Resident claims she believes cooking on the stove in the kitchen, or her kids playing on their cell phones in the living room seem to be times it will trip.

Last night I plugged everything in and turned it on, TV, christmas tree, Cable box, device charges, modem etc. I then turned all 4 oven burners to low so they were all rapidly turning on an off, and sure enough after about 10 minutes click. Obviously the oven is on a completely different circuit.

This is where it gets real interesting, the cell phone suggestion. I have a friend rapid text me 10 times as I hold my cell phone next to the CB. And sure enough, on the 4th text it trips. This house is probably a 6th of a mile as a crow flies to a cell tower.

I guess my question is, where would one go from here? Is it even possible to mitigate the interference that could be causing this from a cellular signal? Or to somehow stop the feedback from the stove into the system?

Any input would be greatly appreciated as I feel I am running out of options.
 
ptonsparky said:
What do the codes indicate. I don't have a sheet.
Click to expand...
I actually reached out to a Siemens dealer in town trying to figure out the same thing. They couldn't give me an answer but said they would look into it. It sure appears to be a revision code, but I can't be certain. Was wondering if someone on here might know the answer to that.
 
kwired said:
And if so do they take away from any (so called) effectiveness of the AFCI features in general?
Click to expand...
I debated trying this, but from what I have read about this method you could decrease the effectiveness or paralyze the AFCI's ability to trip completely. Can't verify the truth in that, but just what I've read. My hope is that if trying that, the CAFCI still detects an overcurrent in the same normal fashion and that the ferrite beads or choke wouldn't also render it's overcurrent protection paralyzed also.
 
AAR said:
I debated trying this, but from what I have read about this method you could decrease the effectiveness or paralyze the AFCI's ability to trip completely. Can't verify the truth in that, but just what I've read. My hope is that if trying that, the CAFCI still detects an overcurrent in the same normal fashion and that the ferrite beads or choke wouldn't also render it's overcurrent protection paralyzed also.
Click to expand...
I didn't figure it would effect the thermal magnetic function, but at same time wondered if you aren't effectively turning a $50 breaker into a $8 breaker just by adding those ferrite beads. I could see it maybe increasing response time on magnetic trip function though
 
I wonder if the receptacle circuit in question is run directly next to the cables for the range, so when the range cycles on and off, it is causing inductive coupling spikes on the receptacle circuit wires that are being falsely detected as an arc pattern?

It's been shown that AFCI breakers are sensitive to RF signals, you can watch some demos of that on YouTube.
 
AAR said:
... This is where it gets real interesting, the cell phone suggestion. I have a friend rapid text me 10 times as I hold my cell phone next to the CB. And sure enough, on the 4th text it trips. This house is probably a 6th of a mile as a crow flies to a cell tower.
Click to expand...

This is not surprising. If you hold a cell phone right next to electronic devices it can interfere with their function. The mechanism involved is usually the amplitude modulation component of a cell phone transmitter output using digital modulation such as QAM, and with TDMA, etc.. The old analog cell phones with continuous FM modulation were less of a problem. The semiconductor junctions inside of electronics can rectify the AM modulated RF and demodulate it just like in a crystal set, and then the resulting low frequency signal may interfere with the intended functions. However, the RF signal will fall off relatively quickly (square law in the far field, and even faster in the near field). Actually, being closer to a cell tower will result in less transmitted power from the cell phone due to its power control function (assuming that the provider being used is on that particular cell tower).
Perhaps you could hold the cell phone next to the outlets on the circuit that are fed from the CAFCI. If that doesn't trip it, then it's not likely the cell phones are causing the problem.

So is this an electric stove? It sounded like it might be given your description.
If it's gas, then the spark igniters could cause interference that either couples to nearby wiring of the branch circuit with the CAFCI as Jraef mentioned, or possibly all the way back to the panel busses. If spark ignition is causing the problem, then a ferrite choke right at the conductors for the stove might help keep the interference from propagating, and it wouldn't affect the AFCI function on the other circuit. This might even help if it's an electric stove, because a spark when an internal contactor is switched could cause high frequency interference that couples into the other circuit nad trips the AFCI.

kwired said:
I didn't figure it would effect the thermal magnetic function, but at same time wondered if you aren't effectively turning a $50 breaker into a $8 breaker just by adding those ferrite beads. I could see it maybe increasing response time on magnetic trip function though
Click to expand...

A ferrite choke around the conductors will have a very small reactance at 60 Hz, an so I think it will have a negligible effect on the magnetic breaker function. And if it's placed over all circuit conductors (e.g., both L and N of a 120V circuit) then the reactance will only be common-mode, with essentially no reactance for the normal differential-mode currents of the branch circuit.
 
Jraef said:
I wonder if the receptacle circuit in question is run directly next to the cables for the range, so when the range cycles on and off, it is causing inductive coupling spikes on the receptacle circuit wires that are being falsely detected as an arc pattern?

It's been shown that AFCI breakers are sensitive to RF signals, you can watch some demos of that on YouTube.
Click to expand...
I personally wired the house and can confirm the 2 cables only come in close proximity in the panel and not even side by side close. Oven is fed through the attic and the living room is fed through the wall. I should note that the panel is in the living room, so the receptacle circuit is the closest connection to the panel in the whole house, the television receptacle is probably less than 7 feet from breaker to receptacle.
 
synchro said:
This is not surprising. If you hold a cell phone right next to electronic devices it can interfere with their function. The mechanism involved is usually the amplitude modulation component of a cell phone transmitter output using digital modulation such as QAM, and with TDMA, etc.. The old analog cell phones with continuous FM modulation were less of a problem. The semiconductor junctions inside of electronics can rectify the AM modulated RF and demodulate it just like in a crystal set, and then the resulting low frequency signal may interfere with the intended functions. However, the RF signal will fall off relatively quickly (square law in the far field, and even faster in the near field). Actually, being closer to a cell tower will result in less transmitted power from the cell phone due to its power control function (assuming that the provider being used is on that particular cell tower).
Perhaps you could hold the cell phone next to the outlets on the circuit that are fed from the CAFCI. If that doesn't trip it, then it's not likely the cell phones are causing the problem.

So is this an electric stove? It sounded like it might be given your description.
If it's gas, then the spark igniters could cause interference that either couples to nearby wiring of the branch circuit with the CAFCI as Jraef mentioned, or possibly all the way back to the panel busses. If spark ignition is causing the problem, then a ferrite choke right at the conductors for the stove might help keep the interference from propagating, and it wouldn't affect the AFCI function on the other circuit. This might even help if it's an electric stove, because a spark when an internal contactor is switched could cause high frequency interference that couples into the other circuit nad trips the AFCI.



A ferrite choke around the conductors will have a very small reactance at 60 Hz, an so I think it will have a negligible effect on the magnetic breaker function. And if it's placed over all circuit conductors (e.g., both L and N of a 120V circuit) then the reactance will only be common-mode, with essentially no reactance for the normal differential-mode currents of the branch circuit.
Click to expand...
I can't fully rule out the possibility of coincidence on the "Cellular Tripping" but it couldn't have been timed more perfect if I tried. The stove is an electric, of the glass top variety. One thing to note is this is the only appliance that remained in the house after the remodel. All other major appliances were replaced.

I will attempt your experiment with holding the phone next to a receptacle on the circuit tonight and see if I get similar results.
 
synchro said:
This is not surprising. If you hold a cell phone right next to electronic devices it can interfere with their function. The mechanism involved is usually the amplitude modulation component of a cell phone transmitter output using digital modulation such as QAM, and with TDMA, etc.. The old analog cell phones with continuous FM modulation were less of a problem. The semiconductor junctions inside of electronics can rectify the AM modulated RF and demodulate it just like in a crystal set, and then the resulting low frequency signal may interfere with the intended functions. However, the RF signal will fall off relatively quickly (square law in the far field, and even faster in the near field). Actually, being closer to a cell tower will result in less transmitted power from the cell phone due to its power control function (assuming that the provider being used is on that particular cell tower).
Perhaps you could hold the cell phone next to the outlets on the circuit that are fed from the CAFCI. If that doesn't trip it, then it's not likely the cell phones are causing the problem.

So is this an electric stove? It sounded like it might be given your description.
If it's gas, then the spark igniters could cause interference that either couples to nearby wiring of the branch circuit with the CAFCI as Jraef mentioned, or possibly all the way back to the panel busses. If spark ignition is causing the problem, then a ferrite choke right at the conductors for the stove might help keep the interference from propagating, and it wouldn't affect the AFCI function on the other circuit. This might even help if it's an electric stove, because a spark when an internal contactor is switched could cause high frequency interference that couples into the other circuit nad trips the AFCI.



A ferrite choke around the conductors will have a very small reactance at 60 Hz, an so I think it will have a negligible effect on the magnetic breaker function. And if it's placed over all circuit conductors (e.g., both L and N of a 120V circuit) then the reactance will only be common-mode, with essentially no reactance for the normal differential-mode currents of the branch circuit.
Click to expand...
This is the kind of stuff that drives us installers nuts, and we don't get paid to try to solve a lot of this sort of problems in the field yet are forced by law which adopted the code that requires we install products that still have design or performance issues.
 
ptonsparky said:
I don't believe the over or short circuit protection will be affected in any way. The question is in it's ability to detect, without error, arcing. Whole house SPD would at least be legal.
Click to expand...
I did install full house SPD on points 1 & 3 of the panel. Indicator windows still showing green, so I think it's still happy.
 
ptonsparky said:
What do the codes indicate. I don't have a sheet.
Click to expand...
For any future person reading this and dealing with these breakers, I finally heard back from Siemens and these are the generation identifier stickers. This appears almost impossible to find.

Gen 2 - No Sticker
Gen 3A - Green Sticker Black Stripe
Gen 3B - White Sticker Black N
Gen 3C - Black Sticker White N
Gen 3C+ - Purple Sticker A00 A01 B00 B01
Gen 4 - Purple Sticker A02 A03 B02 B03
 
ptonsparky said:
I meant the on board diagnostic Flash code that most AFCI breakers have now. An LED will flash indicating, ground, series, or parallel faults.
Click to expand...
Oh I got ya. The diagnostic code just shows arc fault. The plug on neutral style don't have a load neutral point so I don't think there is any level of GFP in it. From what I've read when you test the code, if the light turns on it was an arc fault if the light is off it was overcurrent.
 
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