Why didn’t my CAFCI breaker open? (A tale of three battery chargers)

[JHZR2]

This past weekend, I was away. My Wyze cam alerted me of an issue, and when I reviewed, I was surprised to see a decent spark/arc.

This is in my 2000sf building that is a garage and walk up loft.

The electric service was upgraded when I bought the building. The old SEC, meter socket, and fuse box were replaced. The one lighting circuit (that also provides a few outlets) was connected to the panel via a combination AFCI breaker because of the age of the wiring (the wiring is two conductors in a metal pipe).

The spark is I believe, from an extension cord that connects to a receptacle coming off of the metal pipe/lighting circuit. The extension cord is supported but hangs down from the ceiling to provide two free-hanging outlets in a box.

Inspection of the cord showed no obvious heat/melting/burning damage. But I haven’t been extremely rigorous. The cord still carries power.

I am adding proper circuits for car battery chargers, but the main reason why this was hanging was its central convenience. I had three battery chargers connected to it.

So, before the tale of the chargers:
1) why didn’t my AFCI open?
2) how should I test my AFCI given that this event didn’t open it?


OK, the chargers…

The extension cord has been hanging like that for probably 30-40 years if not longer. It was very convenient.

Connected to it I had a CTEK 4.3, a battery minder 1.25A, and a NOCO genius 2.

When I went to inspect the building, I knew the breaker hadn’t opened because the lighting worked. But I thought it might have been the cord, and so I thought maybe it had acted as its own fuse or something. Imagine my surprise when I saw that there were lights on the charger.

But here’s the issue:

Ctek 4.3 - 4 LEDs lit including the error light, charger stick on step 5, battery on car at 8.65V
Noco 2A - red z warning light on, battery at 12.65V
Batteryminder- no warning lights, still in pulse maintenance mode at 13.4V.

So something definitely happened that the chargers were unhappy and possibly damaged. Yet again, the AFCI didn’t open, the cords seem ok, etc.

What gives?

Thanks!

 

[CDX825]

Some of the test Ive seen guys do on youtube make me question the affectiveness of arc fault breakers. Seems some of them will only trip if there is an arc fault from hot to neutral. Most of the time though the fault is on one side of the circuit such as a loose hot connection or loose neutral connection. They describe theses as "series faults".

I would inspect everything closely and see if anything looks suspect. Obviously something had to cause it to do what it did.

 

[JHZR2]

Some of the test Ive seen guys do on youtube make me question the affectiveness of arc fault breakers. Seems some of them will only trip if there is an arc fault from hot to neutral. Most of the time though the fault is on one side of the circuit such as a loose hot connection or loose neutral connection. They describe theses as "series faults".

I would inspect everything closely and see if anything looks suspect. Obviously something had to cause it to do what it did.

Yes something happened. I’ve since gotten up on a ladder twice and looked at the cord. There is no noticable damage, and it seems to retain continuity no matter how I mess with it.

I would think that a series arc is not what I’m dealing with. That arc would result in extended heating, while what I saw was an instantaneous release which would have to be from a hot to neutral.

Very strange.

 

[alarmguy]

I know this will sound nuts *LOL* but only thing I can think of. Nearby lighting strike/power surge. Meaning are you sure there are no burn marks on metal surfaces in that area unrelated to the wiring? (now dont make fun of me)

 

[OVERKILL]

I'd be losing my mind not knowing where that was happening exactly and the cause.

Assuming it's the cord, I wouldn't trust and would be replacing immediately. Got any pictures of the setup you describe as being in place?

 

[nomas]

The electronics inside an AFCI breaker detect electrical current alternating at characteristic frequencies, usually around 100 kHz, known to be associated with wire arcing, which are sustained for more than a few milliseconds. A combination AFCI breaker provides protection against parallel arcing (line to neutral), series arcing (a loose, broken, or otherwise high resistance segment in a single line), ground arcing (from line or neutral to ground), overload, and short circuit. The AFCI will open the circuit if dangerous arcing is detected.

 

[JHZR2]

I'd be losing my mind not knowing where that was happening exactly and the cause.

Assuming it's the cord, I wouldn't trust and would be replacing immediately. Got any pictures of the setup you describe as being in place?

It was there when I bought the place. Probably been there for 40 years or more.

I don’t like it, and it’s obviously unplugged now and not being used. And, I’m going to put in a new battery charger circuit for the whole place. But this is what I had and what works.

But the concerning thing is that the breaker didn’t open up. And that the Ctek charger seems to have bled down to 6v and ruined my battery.

 

[GMFan]

Get a closer picture of the extension cord plug into the power strip. Is it melted? The plug could be super loose in the power strip and created an arc. What are the two white wires dangling in the photo below the fluorescent strip light? One of the wires looks melted.

 

[Rand]

What is this?

Doesn't look so hot unless its a pull chain.

 

[JHZR2]

Get a closer picture of the extension cord plug into the power strip. Is it melted? The plug could be super loose in the power strip and created an arc. What are the two white wires dangling in the photo below the fluorescent strip light? One of the wires looks melted.

What is this?
View attachment 236782

Doesn't look so hot unless its a pull chain.

Same question from two folks. It’s irrelevant. It’s a poorly set up switch/power for that long fluorescent. It’s worked perfect for 50 years or more based upon ballast age. As I change ballasts I am fixing those. They are rarely used. I have other high intensity LEDs elsewhere.

But point is, while it’s good to flag, it’s not where the arc originated, and not relevant right now.

The arc originated near where the extension cord makes a 90. But even that isn’t really the issue. The question is why didn’t the AFCI open up???

 

[OVERKILL]

Not to be "that guy" but friends of a good friend of mine, acquaintances of ours, had (have) a century home on a nearby avenue. Nice house, had some original knob & tube wiring segments that they were unaware of. Wiring had been there for probably 80 years. One day it shorted out and burned the entire top floor off the house, they were lucky it wasn't a complete loss and that they made it out.

"Stuff happens", even if it's been there forever. I get the concern about why the AFCI didn't work, and that should be investigated further, but you absolutely need to locate the source of the arc, and, given what we see in those footage snaps, there should be some visible witness marks there somewhere.

 

[JHZR2]

Not to be "that guy" but friends of a good friend of mine, acquaintances of ours, had (have) a century home on a nearby avenue. Nice house, had some original knob & tube wiring segments that they were unaware of. Wiring had been there for probably 80 years. One day it shorted out and burned the entire top floor off the house, they were lucky it wasn't a complete loss and that they made it out.

"Stuff happens", even if it's been there forever. I get the concern about why the AFCI didn't work, and that should be investigated further, but you absolutely need to locate the source of the arc, and, given what we see in those footage snaps, there should be some visible witness marks there somewhere.

From the location and video I know where it was. Keep in mind that the video was using night vision. So the intensity may be intensified.

Totally concerning, sure. But it can only be the cord. Nothing else is in the floor joist pocket that the arc originated at. I’m surprised the cord looks fine too. I don’t really get it. There are some minor failing points like this:

But nothing more severe or damaged.

Your point is well taken. Need to understand the failure and out eyes in the cause and ramifications.

 

[dlundblad]

Assuming everything is grounded/ bonded properly, I would start by checking all of your connections from the panel to every junction box, light, and plug. The thing with older wiring is its fine for years and years until it’s not.

Technically, the 2 wire setup in conduit isn’t wrong or not grounded (assuming it’s all metal) The metal conduit can be used as the grounding conductor. (You could also easily add a ground to the existing pipe. I would personally.) A normal breaker is fine to use in this case.. just make sure all the lights and devices are bonded to their boxes.

What brand of breaker/ panel is it? Some brands are notorious for not tripping when they should. Heck, the charger could have made it not operate properly.

*A new cord wouldn’t be a bad idea either.

 

[JHZR2]

It is a CAFCI breaker btw.

 

[someonesomewhere]

It was there when I bought the place. Probably been there for 40 years or more.

View attachment 236763

I don’t like it, and it’s obviously unplugged now and not being used. And, I’m going to put in a new battery charger circuit for the whole place. But this is what I had and what works.

But the concerning thing is that the breaker didn’t open up. And that the Ctek charger seems to have bled down to 6v and ruined my battery.

View attachment 236764

Could the charger have been the source of the problem, and not a casualty of?

 

[dlundblad]

Could the charger have been the source of the problem, and not a casualty of?

Possibly.

 

[Dave Hess]

I was thinking the same. I had a charger go bad on me and burning smell.

Could the charger have been the source of the problem, and not a casualty of?

 

[jhellwig]

Several issues.

An arc that will create a large spark that can dazzle a camera like you saw does not have to be very big. Copper expands massively when it turns into a gas so a very tiny arc can look huge when seen by the eye and still be relatively harmless.

Arc fault breakers look for a very specific kind of fault and function in a way that is hard to define in terms that a human can understand. Not sure how they were created...

Most importantly is all that wiring and electrical junk in the picture you posted is garbage. Remove it immediately.

"Two conductors in a metal pipe" can be the best way to wire a garage or a fire hazard. I don't know without seeing it.

 

[JHZR2]

Could the charger have been the source of the problem, and not a casualty of?

It could have. My MB battery is dead. But the ctek 4.3 connected to it can only pull but so much. Otherwise it would have fried.

So could something have caused a spike? Sure. Enough to breach a gap in an old cord insulation? Unknown. Maybe?

But should it have opened the breaker? That’s the real question. If not on afci, which I’ve learned only isolated against sustained arcs of 5A or more, I’d still think the gfci function would work.

 

[someonesomewhere]

It could have. My MB battery is dead. But the ctek 4.3 connected to it can only pull but so much. Otherwise it would have fried.

So could something have caused a spike? Sure. Enough to breach a gap in an old cord insulation? Unknown. Maybe?

But should it have opened the breaker? That’s the real question. If not on afci, which I’ve learned only isolated against sustained arcs of 5A or more, I’d still think the gfci function would work.

Might replace it jic. They do sell testers that you can plug in an outlet that will test GFCI and AFCI function (saw it on an Ask This Old House segment) but it may be cheaper to replace the breaker.

Or both. Better safe than sorry. But definitely maybe do something more permanent (and safer) with that wiring. Would suck to lose the garage and/or house over a couple hundred bucks in electrical work.