Difference between these AFCI breakers?

Can someone explain to me the difference between the top Combination AFCI breaker and the bottom 3 CAFCI breakers?

I see the top breaker is 20 Amps and has a white sticker in the bottom corner with an “N” on it pointing where the neutral wire connects to it.
The bottom 3 breakers are only 15 Amps and are labeled with a silver “GND” sticker and have a green sticker with black line in the bottom corner. In this panel, neutral wires were all connected next to these stickers as well.

Are there any defects here? This was in a distribution panel in a condo with a remote disconnect/service panel remotely located, so the ground wires were correctly separated from the neutrals.

Thanks in advance for your help.

I don’t know if there is any difference. As long as they tripped when the test button was depressed I would report them as: acceptable, working as intended when tested.
As far as defects, from the picture it doesn’t look like there is a 4-wire feed (isolated ground) for the sub panel.

Tripping any breakers, AFCI or other, is generally not a good idea. Afterwards you will have to explain why you didn’t reset their alarm clocks , reboot their computers, routers, etc (you don’t test standard breakers do you?). It does happen accidentally (Federal Pacific comes to mind) but I don’t recommend it as a normal procedure.

Where possible in the SOP means a vacant house to me.


Looks like the cross bar is tying the neutral bus.

Looks like the 15 amp CB’s have indicator lights which tell you if it tripped due to an arc fault or a ground fault. The sticker is adjacent to each light.

isn’t this just a combination AFCI breaker that protects against parallel arcing conditions and series arcing conditions? I don’t think this is a dual function breaker protecting against ground faults. This is another reason why I’m confused about the differences between the breakers in the photo.

David, I couldn’t confirm, but I saw armored cable going through the wall around the corner in a closet, that I suspect housed the feeder cables from the main disconnect to this sub-panel. If this is the case, my understanding is the armor around the 3 feeder wires can serve as the isolated ground (grounding the panel cabinet which is bonded to the grounding bus).

Please someone correct me if I am wrong.

Yes those are standard combination AFCI circuit breakers. The 15 amp will also indicate if it tripped due to a ground fault but it does not provide GFCI protection for that you would need a dual function type. Yes type AC cable has a metal jacket that is suitable for use as an EGC although I do see a large green conductor which does seem to come into the panel with the feeder. If so it could be fed with MC cable which contains an insulated EGC.

Thanks Robert. Just for my understanding (not my clients since is way beyond standards), any idea why they might have used a different type for the 20 amp CB, which doesn’t detect a ground fault? The wiring to all of these should be the same, correct (with a hot wire and a neutral wire tapped to each breaker)?

That’s what the electrician had on his truck :smiley:

You really need to look that up on your own…Yep!

Really ? That right there is crazy!
Then what is the main purpose in using them?

We have to know what that is before we go further…Yep!

Class A GFCI protection is (mostly) for the protection of people and has a trip setting of 4-6 ma. If you want that type of protection and also AFCI protection you need a dual function AFCI/GFCI breaker. A combination AFCI breaker is not a dual function breaker. The 15 amp CB’s in the OP is a combination type (parallel and series arc’s) and will indicate if the breaker tripped because of a direct fault to ground like if a hand tool was internally connected from hot to ground. It does not have the 4-6 ma trip setting built in.

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So! It has to be shorted out directly to trip, in GFCI and/or AFGI to trip at the 4-6 milliamps?
Or does the GFCI trip ahead of the AFCI?

I’m not making myself clear…
Is there a difference between the GFCI and the AFCI trip on a combo breaker?
If yes! How much?

Think of it this way if you have a standard 20 amp circuit breaker it will trip is it’s:

  1. Overloaded (current in excess of 20 amps, the larger the excess the faster it trips)
  2. There is a fault from the hot to ground or
  3. There is a fault from hot to neutral

Now to that add a sensor that can detect arc faults and you have an standard arc fault CB. You still do not have a component of the CB that measures the requisite 4-6 ma for GFCI protection so it is not a dual function CB and cannot be used for GFCI protection where GFCI is required like in a bathroom.


good explanation, Robert.

Yes! Very good! So what is the purpose of using a combo?

probably something to do with series and parallel arcing, YEP!

Nobody cares about the crossbar, YEP!