AFCI Circuit Breakers
For those that are interested here is an example of some of the issues going on with AFCI circuit breakers. Copied from Mike Holt's Forum.
"Had a call Friday night from a customer whose new house we wired 3 years ago. She said that all of the Eaton AFCI breakers and Dual function breakers in the panels tripped within a few seconds.
When I got there a little later I found them all tripped. None of the standard single pole or double pole breakers were tripped. I reset all of them and within 5 minutes they tripped again all within a few seconds. The flash code was six times which means self- test fail, defective breaker.
After resesting them again 5 minutes later all of the breakers on line 1 tripped at the same time.
In coming voltages checked out ok. Utility company said they weren't aware of any problems. This house is on its own transformer. Owner stated they haven't changed or added any new appliances. They also aren't aware of any lightning strikes recently.
Eaton is sending all new breakers to me.
Anyone else ever experienced this or have ideas of where to start troubleshooting."
Just another example of unproven technology sent into the field without enough testing
Comments
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Sensitive little buggers. I wonder, though, if there might be just enough of an odd connection somewhere between the transformer and the main switchboard to annoy them.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
Anyone have any good or bad experiences with Square D AFCIs. Either QO or Homeline? I currently have a Homeline panel, but would consider QO.
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I've had a couple of QO breakers installed next door for several years now, I'm unaware of any issues with them. I did exchange one during the initial install, as it didn't trip when I used my Amprobe ACFI tester (INSP-3). I later heard that the only legit test is the test button, so take that with a grain of salt.
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Not sure if any brands are exempt from random tripping.
Sq D Qo has usually been considered the top of the line for years even used on commercial jobs FWIW. Don't know how their GFCI/AFCI breakers are holding up. Will try and find out.
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I put four Square D QO combination arc fault/ground in when I upgraded my service in 2017. The only nuisance trips I’ve had were caused by a pretty fancy computer running graphics intensive software. Otherwise they haven’t been a problem at all.
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Wonder if putting a transient 'protector' on the panel would solve it.
30+ yrs in telecom outside plant.
Currently in building maintenance.0 -
I use Square D QO breakers. Only the one issue noted previously with one breaker not liking one particular vacuum cleaner.
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Solar flares, seriously.
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Edited to fix the colors of the test buttons
I think QO and Homeline breakers have more or less the same innards just in a different package. I have 2 QO AFCI breakers that I installed about 20 years ago and I don't think I have ever had them nuisance trip. They are on the 2 circuits that run most of the lighting and general purpose receptacles on the main floor of my house so they are the bedroom, living room, and the 2nd bedroom that has my ham shack in it. When I had an issue with an antenna that wasn't balanced that put a lot of RF in the shack that tripped a couple GFCIs, caused the CO detector to save a reding of like 486 ppm, caused the thermostat to reboot and caused the garage door operator to lock up, they didn't trip. They are whatever type has the light blue test button.
I did have an AFCI receptacle trip a few times with a dehumidifier plugged in to it but it isn't clear that there wasn't a problem with that dehumidifier, it ultimately had its refrigerant escape and it has never tripped on the Aprilaire dehumidifier.
In the last 5 years or so I added a circuit for a bidet seat in my bathroom that is on a afci/gfci breaker and that has nuisance tripped but only when there is a power outage, either something about the power going out or coming back on causes it to see something it doesn't like. The last time it tripped there was nothing connected to the circuit, it was just romex to a single receptacle but it was when the power went out and came back on. It has a purple test button.
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Back to the OP. I think Eaton has some odball designs of AFCI breakers. They I think have a breaker that has a neutral connection for the breaker but not for the load. I didn't look in to this too far, maybe i will now, but they may be for use for the rule in the code about a certain type of breaker in the panel allows you to use an AFCI receptacle to meet the requirement in combination or they may have just been trying to get away with not having a neutral load connection. Of course everyone has a bad batch of product sometime too. I don't know that I would take accounts of people having problems with specific models of AFCI breaker as an inherent problem with the technology.
Also, refrigerant and oil are nonpolar. There should be no leakage current in a properly designed compressor. I more suspect that issues with refrigerators and GFCI trips have to do with wiring and terminals that aren't adequately protected from condensate and ice.
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Time will tell.
All I know is the electricians on the electrical forums are not happy campers about AFCI. Most of this is in new homes obviously.
Seems to be more complaints about AFCI every day
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Funny thing about that.
Monitor tops do have some leakage. What's weird is when you pull the charge it goes away. Even on my 1933 before I worked on it I measured leakage, pulled the methyl formate out and it was completely gone. Charged the machine it was back.
Obviously SO2 and methyl formate are very different from modern refrigerants but I think a big part of the issue is the terminals are at the bottom of the compressor where liquid refrigerant can lay.
And yet it's not near enough to trip a GFCI.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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wonder how much of this is related to the minor errors made in wiring that are detected by the AFCI? For example, neutral contacting ground will trip the circuit and can be a pain to isolate on a new install.
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If the neutral was contacting the ground it would probably show on a plug in tester
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there are lots of times where there is a nick in the insulation or stray strand of wire or metal that goes unnoticed that only touches when you move the device when you unplug or plug something in or operate a switch.
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Er, i looked again, the one that trips with power interruptions is purple, the ones that have never tripped are light blue.
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No. Not the $7 testers. This-century GFICs use a radio-frequency signal to determine how-far-out the N-G connection is. (AFCI is a fancy over-price GFIC.)
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only contacting when something moves.
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Thinking about all this and realising that I need some eddication here from some of the sparkys. Please!
It was my impression that a ground fault detector is intended to trip if there is leakage current in the ground circuit — either from the neutral or from the hot. Which seems simple enough — the neutral and hot currents should be exactly equal, and the ground zero. Is this so?
On the other hand, the arc fault is intended to trip if it senses (probably from wave form distortion?) an arc (almost by definition very short term) between either hot and neutral or hot and ground.
How does an arc fault interrupter distinguish between a wave form distortion or inductive or capacitance spike coming from the supply side and one reflected from the load side?
Enlightenment will be much appreciated…
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
GFCI's work by measuring the current through the hot and through the neutral. I don't think they care about ground at all. If the current through the hot and neutral do not match almost identically it trips because clearly it's going somewhere other than neutral.
AFCI I don't know. Yet.
But now you have me curious.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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What @ChrisJ posted about GFCIs is correct.
GFCI don't care and don't need a ground to work. That is why it is legal to install a GFCI receptacle with a ground terminal on an old knob and tube or other ungrounded circuit and just not attach anything to the ground terminal. GFCI measure hot and neutral current and will trip if they do not balence.
I don't know exactly how AFCIs work but @Jamie Hall discription of how a AFCI work is good enough for me.
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My guess is they use a DSP chip to capture and analyze the waveform of the power and compare to some sort of transform of known arcs.
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Thank you!.
I'm old. I still like fuses. They have an utterly predictable total energy (time times current) trip, varying with the type of fuse… and slightly with the ambient temperature around the fuse… and they will blow on significant arcs (ask me how I know!)
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England1 -
both those links in that post seem to be broken. i would hope square d has a good description buried somewhere in its training materials.
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Oh, and the older QO AFCI breakers that I have (which may not even be combination afci) make a faint buzzing noise presumably from the power supply. Depending on how they are aligned with the cover I can hear them in my headboard of my bed that is just above the panelboard in the basement.
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I am old too. Fuses are much safer than breakers imho the are available in high interrupting capacity as well.
problem is people over fuse things, and you have to have spares available. but they don't do funky things like breakers.
And the old plug fuses can always be replaced with a penny and cartridge fuses replaced with copper tubing lol🤣🤣🤣🤣
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That's the part I don't entirely understand.
Instead of engineering a fuse panel that had fuses that could not be swapped for other sizes, circuit breakers were introduced. When a panel is properly sized the chances of blowing fuses is slim so they aren't really that much of a problem.
Go back 70 years and someone could have designed a fool proof (fairly…) fuse panel and standardized it.
I can only assume reusable circuit breakers was a much easier thing to sell to people who were used to constantly changing fuses due to grossly undersized electrical panels / services.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Or all of the above, @ChrisJ . It was partly because they were an easier sell — but also because very few people have the whatever to swap circuit breakers to solve blowing fuses on overloaded circuits, so it's a safety issue as well.
As it happens, Cedric's home has about 100 circuits. Only three of the 10 or so panels and subpanels are equipped with circuit breakers, and they are subpanels with master fuses in the main switchgear. The rest of the panels are fuses, but all are fitted so that only the correct sized fuse can be used (some screw in plug for individual circuits, some master fuses).
And at that the plug fuses, despite having different base sizes for the power rating, aren't idiot proof, although it would be hard as the sockets are designed so that shorting them would be very difficult (older designs the penny trick works fine)… and smaller cartridge fuses can be jumped with copper pipe.
There is no such thing as an idiot proof device. Idiots are always more ingenious than you are or I am…
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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Plug fuses originally had the Edison "light bulb threads" and you could screw any plug fuse into the fuse holder from 1 amp to 30 amps.
Later on (40s-50s just guessing) they came out with "fusestats" which are plug fuses with different threads. Then you had to buy "fusestat adapters" which was an adapter to screw into the Edison based light bulb fuse holder in the panel..
They had adapters for different threads such as the blue adapters would take a 15 amp max fuse down to a 7 1/2amp but a 20 or 30 amp would not screw in. Different adapters for 20s and 30s.
The adapters would screw in but were made so they would not unscrew without difficulty so they were semi tamperproof. The homeowners couldn't unscrew them without getting shocked usually. You could get them out if you killed the power to the panel but not easily.
As a side note, in the old days when the homeowner had a short circuit the electrician would remove the blown fuse and replace it with a light bulb and the light would light because of the short. When the electrician fixed the short the light would stay off.
I had an elderly lady in town years ago that her husband passed away. She wanted to put power in her detached garage for a garage door opener because she couldnt lift the door.
I went in the basement and found she had a 30 amp 120 volt service protected by a switch and a 30a plug fuse
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Those were the days…
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
Fusestat is buss's branding for time delay type s fuses. Fusetron is Buss's branding for time delay plug fuses.
Using an incandescent lamp as a resistor to limit the current is common in electronics. You bring it up with a variac and a series lamp and an ammeter to limit the current if something is shorted.
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I've personally never used a light bulb for this. Just a variac and an ammeter and voltmeter.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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plenty of 25 w lamps that no one wants around.
it keeps things from burning up if there is a dead short or if you don't quite understand what is happening. A dead short will draw a lot of current even at a couple volts.
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The ammeter does that in my case.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Oh, look, 10a at 3v. Now it is 0. What;s that smoke?
especially with stuff that has circuitry that doesn't energize other parts of the circuit until it hits some voltage threshold.1 -
I'm gonna play the same card others on here do constantly.
I've been doing it that way for 26 years without a problem.
:)
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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In my experience, with my own wiring, they like dedicated neutrals. Had a similar problem. Three afci breakers worked fine , each with dedicated neutrals. Two that shared a neutral tripped when carrying a load. Removed all of them and replaced with normal breakers and installed gfci outlets where I needed them. I got tired of going in the basement to reset them. But it took days of troubleshooting in a dirty, tight crawlspace. My best guess is two phases on one neutral is bad for these things.
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Isn't the neutral required to go through the breaker? If it is I don't think you be able to do a multi wire branch circuit.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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