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Discussion Starter · #1 ·
So I needed extra circuits to wire a kitchen reno. There was an existing small sub panel (60A feed from main) which was full so I replaced it with a brand new homeline sub panel with plenty of circuit space. There are 2 other CAFI breakers in the sub with no issues. I wired some general use wall receptacles which, as per code, were protected by a combination arcfault breaker. This circuit also has a ceiling fan wired on it (with wall switch) but the fan didn't get installed until they bought the darn thing about a month later. Before the fan was bought, I energized the plugs (and the maretted fan circuit), tested them all and everything worked fine...no tripping. A month later I wired the fan in and fired that puppy up. Fan and fan lights worked well for about 30 minutes, until the homeowner came home and wanted to pull the pull chains on his new fan. He operated the fan and then the CAFI tripped. Naturally, I assumed a bond was touching the Neutral somewhere so I checked and it was not the case. I disconnected the first plug from the feed and confirmed the feed was good as the breaker held. Connected the feed again and opened the fan switch box. With the fan switch extended out of the box, the CAFI reset and held...I pushed it back in live expecting the breaker to possibly trip but it did not. It stayed working for a whole day then tripped again. Went back, took the hot leg off the fan wall switch and the circuit still tripped. I then took every plug out again and checked the feed again....This time, with not a single thing connected to the feed (Hot and Neutral both disconnected, just a open ended 14/2 connected only at one end to the CAFI... it still tripped. Put in a normal breaker and she held. Put a SECOND brand new CAFI breaker in and it tripped immediately...so likely not a bunk ARCFAULT breaker. Last ditch effort, installed a normal breaker and fed and ARCFAULT receptacle at the panel. Then put every single device back in the circuit one at a time, energizing the circuit each time to verify. Lastly, slapped the fan back in the mix and everything worked fine. Circuit has been fine for 2 days now. Any ideas? Comments? Advice? This one bothered me as there was no culprit found. Also, anyone know of any specific diagnostic tools that would be useful in one of these predicaments? Sorry for the novel.
 

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Is the home run in a connector at the panel? Maybe clamped too tight?
 

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I know we are not supposed to do it but try a different manufacturer of the AFCI breaker. We all have done it in a pinch. A BR or GE In a Siemens panel. The CH and QO are a problem. All breakers go through design problems and now with " The Covid" they might be substituting components.
 

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I've heard that Siemens is having a problem with their Arcfaults.
 
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This time, with not a single thing connected to the feed (Hot and Neutral both disconnected, just a open ended 14/2 connected only at one end to the CAFI... it still tripped. Put in a normal breaker and she held. Put a SECOND brand new CAFI breaker in and it tripped immediately...so likely not a bunk ARCFAULT breaker. Last ditch effort, installed a normal breaker and fed and ARCFAULT receptacle at the panel.
Did you shorten the original home run and add a new piece between the panel and the AFCI receptacle? Any chance that piece was damaged?

I mean if the AFCI breaker tripped with an open-ended wire it's got to be the breaker or the home run you would think.
 

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Discussion Starter · #9 ·
Did you shorten the original home run and add a new piece between the panel and the AFCI receptacle? Any chance that piece was damaged?

I mean if the AFCI breaker tripped with an open-ended wire it's got to be the breaker or the home run you would think.
I totally agree with you, but a few days prior to the AFCI receptacle being added in the open ended feed tested fine and didn't cause any tripping. I inspected the cable and couldn't see any signs of damage.
 

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Discussion Starter · #10 ·
Did you shorten the original home run and add a new piece between the panel and the AFCI receptacle? Any chance that piece was damaged?

I mean if the AFCI breaker tripped with an open-ended wire it's got to be the breaker or the home run you would think.
Also, no, didn't shorten the home run, it had appropriate length to reach the AFCI plug location.
 

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You stated in your first post this is a renovation. Did anything get nailed or screwed to the wall or ceiling that might have nicked the wire after the initial install?
 

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Discussion Starter · #12 ·
I know we are not supposed to do it but try a different manufacturer of the AFCI breaker. We all have done it in a pinch. A BR or GE In a Siemens panel. The CH and QO are a problem. All breakers go through design problems and now with " The Covid" they might be substituting components.
That was kind of my rationale with the AFCI receptacle...it's made by Leviton so figured maybe the electronics would have a slightly different sensitivity or something.
 

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Did you try a stab on the other bus? Maybe some weird interference on the bus causing the trip?
 
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Discussion Starter · #14 ·
Are there any solid diagnostic tools that anyone knows of that could analyze these types of issues? Oscilloscope maybe? I know Siemens has a tester but it doesn't look adequate for very thorough testing. It would be nice to see what exactly in the sine wave the breaker is seeing. Last time I used a scope was about 17 years ago... hahaha . I almost want to call the manufacturer and see what they say.
 

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So damn strange.
I think Leviton is using the old Federal NeverTrip technology in their arc fault devices. 🤣 I use them whenever I can, even by running armored cable to the first device. Leviton even makes an AFCI switch but I have never seen it.
 

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Estwing magic
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Are there any solid diagnostic tools that anyone knows of that could analyze these types of issues? Oscilloscope maybe? I know Siemens has a tester but it doesn't look adequate for very thorough testing. It would be nice to see what exactly in the sine wave the breaker is seeing. Last time I used a scope was about 17 years ago... hahaha . I almost want to call the manufacturer and see what they say.
I’m not sure why but I get the feeling you’re overthinking this. 😊
 

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Discussion Starter · #19 ·
You stated in your first post this is a renovation. Did anything get nailed or screwed to the wall or ceiling that might have nicked the wire after the initial install?
Yeah, drywall went in. I thoroughly entertained the idea that a drywall screw could have something to do with it but it or a brad nail for the trim but nothing trips with the AFCI receptacle......which you would suspect it would. Hard to convince a customer to rip brand new painted drywall down without solid evidence of a fault.
 
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