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I have a panel with AFCI in most of the 15/20amp services to receptacles.

My question involves places like kitchens and bathrooms. While they appear to have GFCI protection from the first receptacle and then the others wired from the first ones load side, they do not have AFCI breakers at the panel.

So for example, there’s a dedicated 20amp for the microwave. It does not have AFCI and conversely in the master bedroom receptacles are fed from an AFCI.

While I’m sure this is intentional, I am curious as to why. I have a high level understand the differences between GFCI and AFCI, and knowing that makes me wonder why you wouldn’t want every receptacle fed off an AFCI, with GFCI in wet locations.

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    Does this answer your question? Why aren't GFCI and AFCI breakers combined or used together?
    – isherwood
    Commented Dec 19, 2023 at 22:01
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    More: AFCI and GFCI on the same circuit? | Where should I NOT use a GFCI or AFCI?
    – isherwood
    Commented Dec 19, 2023 at 22:03
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    @isherwood not fully. I think I’d still like someone to chime in. So in a residential situation the reason to not put arc faults in certain places where code doesn’t mandate it , is simply to avoid false positives by assuming the types of use of said receptacle based on its location?
    – MZawg
    Commented Dec 19, 2023 at 23:06
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    @FreeMan I suppose but the phrase elicits professionals to share knowledge outside of some book. My Haynes manual tells me to get to my block coolant temp sensor to remove the front bumper, wheel, and skid plate, yet just turning the wheel hard right allows an arm and a socket wrench through to reach it. But maybe by asking if this method is wise, someone could note possible ramifications of doing it that way. I don’t think opinions and anecdotal evidence of something are the same.
    – MZawg
    Commented Dec 20, 2023 at 19:33
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    Ended up being closed as a dupe, anyway. Also, to your point, that's why it takes more than 1 vote to close a question.
    – FreeMan
    Commented Dec 20, 2023 at 19:37

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TL;DR Money

The linked posts in the comments give some good explanations of the history of AFCI and GFCI protection. But as for the specific answer to your question:

why you wouldn’t want every receptacle fed off an AFCI, with GFCI in wet locations.

The answer is that in a perfect world, there is no fundamental reason not to do so.

However, most of us don't live in a perfect world. Most of us have to balance cost vs. benefit.

In a new house, $1,000 for AFCI everywhere and GFCI for wet areas, etc. will hardly be noticed. You don't get an itemized bill when you buy a new house.

However, in an existing house that $1,000 as a sudden extra government-mandated (the NEC is not governments, but it is local governments that require the NEC be followed) extra expense would not go over well. And the expense could even be quite a bit more. In my house before panel replacement a couple of years ago, the AFCI requirement would have essentially required the panel replacement (that I eventually did for other reasons), so it would have been a lot more than $1,000 to add AFCI everywhere. On the other hand, when I did a panel replacement for other reasons, if I had to add AFCI everywhere (and GFCI where I didn't already have it - kitchen did from previous renovation, bathrooms because many years ago my electrician basically told me he was going to do it (I don't remember him really giving me much of an option!)) then I might have waited longer on doing the panel replacement. And that panel replacement solved a lot of other safety issues, including some that I (and my electrician) didn't even know were lurking in the old panels.

False positives on GFCI - very rare with modern appliances, unless there is an actual ground fault.

False positives on AFCI - a little more common than GFCI, because the detection process is more complex. But gradually this problem will go away with newer appliances because manufacturers will redesign to avoid high return rates.

My personal take on it:

  • GFCI in key locations (basically the older GFCI requirements - within 6 feet of a sink in kitchen or bathroom) - that can be done so easily and inexpensively (around $15 per circuit by putting it in at the first receptacle in each circuit, no panel work needed so a basic DIY task in most cases) that if you have a bathroom or kitchen 30+ years old that never got GFCI, do it now.
  • GFCI in other locations, AFCI everywhere - no rush.
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  • Money; never mind that AFCIs are supposedly flakey AF.
    – Huesmann
    Commented Dec 20, 2023 at 13:34

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