Siemens/Murray AFCI ; arcing on stabs

[Chuck0]

Hi, I am new to posting on the forum here, but I have read a lot of good pointers from these very forums .
I am a general residential and light commercial repairman for about 40 years.
I have been invited many times to troubleshoot issues.
Last year I was asked to track down what seemed to be very random residential AFCI tripping, even into sub panels. All the panels are Siemens and all the breakers were Murray. There were 8 different breakers tripping. Sometimes 2 months between and sometimes the next day. Most tripping seemed to happen about an hour after dark.
I brought my TinySA spectrum analyzer to the house and found that the gas range and the range vent system both had a huge amount of wide band RF being generated even just sitting in stand-by. I put a couple of Plug in RF snubber modules in series with the plugs and I thought I had it figured out.... Well 5 weeks later another trip. I had looked long and hard at this, so I called Siemens. They suggested that I borrow their Recording Diagnostic Breaker (RDB), which I did.
Just by chance, running through the multiple trips in my head, I grabbed what I felt was the most tripped breaker and went to replace it with the RDB. When I pulled it out small burn marks were evident on the shiny relatively new stabs of the Siemens panel. Looking closely at the Murray AFCI I could see heat discoloration at the bus connection point; . So, I cleaned the Stabs well with some fine ceramic scrubbing pad and installed the borrowed RDB. That breaker happened to be the culprit!
RDB installed completely stopped all the tripping. Now after going to the bother of requesting and having the RDB sent to me I couldn’t even use it because I couldn’t get a trip.
At any rate I bought a new, this time Siemens AFCI, replaced the RDB and solved all the nonsense tripping.

Well that was all good until this week, 5 months later, we had another set of trips within 3 second of each other. The vacuum cleaner tripped one circuit, and 3 seconds later the lights go out- both on the same phase. The owner went right out and bought 2 new Siemens AFCI breakers and I installed them this morning... and what did I find ; more burnt stabs , both on the same phase.

When I found the first burnt breaker I couldn’t get any response from Siemens concerning this issue.

Now the home owner is concerned about the overall safety of his electrical system.

I am wondering if anyone has experienced this issue in the past ?
Murray is supposed to be compatible with Siemens according to Siemens.

I hope this doesn’t become a Zinsco problem, but it will probably be ok since the AFCIs trip before they can weld on .

If anyone has experienced this or more importantly found a cause, I would like to know. I am hoping the new Siemens breakers do the job

I’m pretty sure since the arcing was happening on the bus all the breakers were reading the noise on the line that is why such random tripping.

If I can figure out how to get pictures uploaded , I will

 

[GoldDigger]

Your description of yourself as doing troubleshooting, and the Profile Occupation entry of "Repairman" leads to the question of whether you are also a licensed electrician?

 

[Chuck0]

Not licensed, but have worked in trouble shooting for contractors . I’ve also done some work in embedded microprocessor systems for radio stations, educated in electronics.
I enjoy solving mysteries
I worked along side spec house builders starting at 18

 

[Chuck0]

(I can’t understand how to upload photos here. I’d like to share some if that is ok, and if someone could tell me how .... maybe it’s my age )

At any rate I’ve been in all phases of mostly residential construction for 44 years now, with much of the time dealing with electrical both new and old.

 

[ramsy]

If anyone has experienced this or more importantly found a cause, I would like to know.

Welcome to the forum Chuck,

Modern breakers with integrated circuits don't last long, before utility excursions, solar storms, or other elements cause the test buttons to fail in the energized position.

Forum members have reported plenty of nuisance tripping with these xFCI computers, but few report solving the problems, much less get conclusive answers from the forum.

The escalating rate of xFCI false positives result in non-compliance, when nuisance trips are solved by replacing the computers with old faithful thermal-magnetic breakers.

There is no compliance with replacement code xFCI, remodel outlets without inspections, much less market demand for xFCI troubleshooters, and contractors wont need you if solutions are found freely on this forum.

If a home owner did compensate you over a year long nuisance resolved, that is a rare angel, unless of course more developers refer your going concern before those pesky computers get removed.

 

[Jraef]

Siemens and Murray, within the era of AFCIs at least, are not just “compatible”, they are the exact same breakers with different stickers on them. So the fact that replacing them seemingly resolved the problem might point to a “bad batch”, because it would be likely that when installed, they were all bought at the same time from the same manufacturing lot. Its worth bringing up to Siemens as a product quality issue and ask that they provide replacements for all of the rest of the breakers.

There was a class action lawsuit against Siemens for all of their AFCI nuisance tripping issues. I don’t know if that involved the bus connections though. All of the breaker mfrs have had nuisance tripping issues over the years, requiring them to issue revised versions with firmware that is better at discriminating against “normal” electrical disturbances caused by brushed motors (ie vacuum cleaner) or certain types of electronic non-linear power supplies and inverters that are now very common on appliances. If those breakers are over 10 years old, that may have been the issue. The burn marks on the bus might just be coincidental.

 

[curt swartz]

Are you sure they were burn marks? Not scrapes from the breaker being installed/removed? Or possibly dried grease from the breaker connection? I don't know if Siemens uses grease but some manufactures do.

 

[Chuck0]

That’s an interesting thought Jraef -
From all I could read the breakers are just marketed differently, and supposed to be the same physically, and I’m sure the electrician who installed these buys them in large quantity. Maybe your onto something with a bad batch !
I’ll hit Siemens up with that thought of a bad batch
5 months ago, I sent two email to Siemens with my concern and they would not return any response whatsoever in any way - that tells me this is something they don’t want to talk about from an engineering perspective, but maybe they would consider a bad batch - great idea !

 

[Chuck0]

Yes- defiantly burn marks Curt.
The first replacement 5 months ago were very pronounced.
This recent event they were not as heavy, but still there.
You can also see the discoloration in the breaker contact side from heat

 

[Chuck0]

So, one of the points I’d raise to anyone having what seems to be AFCIs tripping on different breakers, and appears to be nuisance tripping, is there could be an arc on the bus- an arc on the bus is heard by all the breakers. The breakers can’t tell what side of the breaker the noise is being generated from, and so you get different breakers tripping for no apparent reason- a clue might be that they are on the same phase.

These recent breakers might have been arcing before, but when I replaced the first breaker 5 months ago, I probably disturbed them and possibly reseated the contacts, as the first replacement breaker sat between the two recent ones on a different phase.
Originally we had tripping on both phases, this time both trips were on the same phase.
The point being , that the nuisance tripping might not be the noise/arc of the brushed motor running in the house, but might be inside the panel -

I’m very curious if anyone else has seen this ?

 

[tortuga]

Hi, I am new to posting on the forum here, but I have read a lot of good pointers from these very forums .
I am a general residential and light commercial repairman for about 40 years.
I have been invited many times to troubleshoot issues.
Last year I was asked to track down what seemed to be very random residential AFCI tripping, even into sub panels. All the panels are Siemens and all the breakers were Murray. There were 8 different breakers tripping. Sometimes 2 months between and sometimes the next day. Most tripping seemed to happen about an hour after dark.
I brought my TinySA spectrum analyzer to the house and found that the gas range and the range vent system both had a huge amount of wide band RF being generated even just sitting in stand-by.

I would verify that the equipment ground is connected ( and has continuity ) to the range hood fan.

I had looked long and hard at this, so I called Siemens. They suggested that I borrow their Recording Diagnostic Breaker (RDB), which I did.

I have never herd of of this breaker, how do you use it? what number did you call to get it? Can you post a photo of it?

 

[ELA]

I brought my TinySA spectrum analyzer to the house and found that the gas range and the range vent system both had a huge amount of wide band RF being generated even just sitting in stand-by. I put a couple of Plug in RF snubber modules in series with the plugs and I thought I had it figured out....

Next time it might be interesting to use your SA to monitor emissions at the panel itself. If stab connections are at issue I would expect to be able re-produce a trip by vibrating the breakers ( while under sufficient load).

 

[Chuck0]

I searched everywhere with my TinySA including the panel.
Even though there was a lot of RF wide spectrum noise generating at 2 appliances, this did not trip the breakers.

The culprit is the intermittent arcing at the stabs. The problem finding it is the “intermittent” part and perhaps I could have spotted it with TinySA if I was there at exactly the right time; since they are AFCIs they trip when they arc. Now if they were Zinsco you could just walk up and listen to the arcing
The problem usually happened in the evening about an hour after the sun went down. The panel faces west, so there is some heating from the afternoon sun.

I did check for ground and neutral resistance and did not find any issues.

If I’m called out again, maybe I’ll just check all the stabs.

 

[Chuck0]

As far as contacting Siemens :

support.usa.automation@siemens.com

Lots of email and phone took place and they really wanted to help. Fantastic support team !

Recording Diagnostic Breaker:
I don’t have a picture of the RDB.
It looks exactly like a regular breaker : except, Pushing the trip button for a certain amount of time when powered puts it in Bluetooth Link Mode.
Of course you get their App.
After a Arc Fault trip, and you are in proximity you can down load the arc signature and send it in to Siemens for examination all from your phone. That is supposed to help them direct you to the source of arcing.

 

[Chuck0]

Trying to upload another picture

 

[tortuga]

I have seen DIY installers that did no get the breaker U clip aligned with the stab and forced the breaker so just one side of the U was making contact.
Looking closely at that photo of the stab the scratch on the bottom makes me suspect the breaker might have been installed incorrectly like that.

 

[Chuck0]

There is a fine scratch there, but I’m thinking from it’s shininess that that probably happened when I pulled it off.

I honestly can imagine how you could miss the allignment on a full sized breaker: that being said, I could see someone having a problem with those side contact high density ones.

No, on the electrician that put it together- he is one of the most respected electrical contractors in our area, and he doesn’t hire help because he doesn’t trust others working for him , to avoid mistakes.

Good thought though , thanks

 

[Chuck0]

I can’t upload the video, but here is a screenshot of a frame of a video where I’m polishing the stab with ceramic fiber, and you can see pits in the metal. It could be caused from the arcing or maybe it was there before and is the cause.

We will see how these new breakers do.

Like Jraef said, maybe bad batch of original breakers.

A Time Study will tell

 

[ramsy]

A Time Study will tell

Tomorrow's solar storm may destroy the delicate electronics in AFCI & GFCI circuit breakers (xFCI), unique to North America's NFPA code-making industry.

If test buttons fail to disconnect device power after a solar storm, just like local-utility surges, no warning will be provided for the safety device failures.

Shawn Dahl, the service coordinator for the Space Weather Prediction Center, which is part of the National Oceanic and Atmospheric Administration..

This was the second .. space weather equivalent of a hurricane watch, to be issued by the center in the past 19 years.

The first, in May, put the United States on alert for a severe solar storm that appeared to be on its way to Earth. That solar storm reached the highest level of “extreme,” but the early warning allowed electrical utilities to prepare and helped prevent major outages.

As if uninsurable flood & natural disasters are not enough risk, owning property now bears the unconscionable burden of beta testing computerized xFCI fuses that frequently nuisance trip from false signal noise, and ultimately fail in the "ON" position.

Such "Increased Hazard" not insured against is subject to state insurance codes; intended to non-renew and cancel hazards, installed by unqualified persons, lacking building permits & inspections.

The insurance statutes were not legislated to mandate unreliable fuses, which the NFPA-70 code making industry has done since 1999.

 

[ramsy]

The international space station flew through this solar storm Thursday night without blowing fuses, since the NFPA's code making industry members have no jurisdiction to mandate AFCI or GFCI in aerospace vehicles, or critical systems.

So insurance code non-renewal and cancellation for "increased hazard" not insured, occurs on earth by either removing xFCI that nuisance trips, or by not replacing xFCI that fails in the "ON" position.

Either way, insurance adjusters can blame fire hazards & casualty on any missing xFCI, if preventable per NFPA-70 Article 210.8, 210.12, & 406.4(D), or cite equipment listing violations that ignored monthly test button procedures, per 110.3(B).

One can only hope a national code can be adopted, which recognizes critical terrestrial refrigeration, cooling, heating, appliance, and lighting systems, which shall be exempt from unreliable safety devices that leave people in the dark, or compel unforeseen insurance disqualification, much less without refund of premiums.