My brother-in-law, licensed master electrician was just visiting us. After looking at my break panel he strongly suggested I should replace most, if not all, of my CBs with AFCI.

I have a 200A GE main panel and have two Square-D subpanels. Both fed by 2AWG and ran from 100A breakers in the main. (one in basement about 35ft from main panel and 2nd subpanel is adjacent to main--added for additional circuit breaker space).

Should I replace any of the original breakers (and those in the subpanels) with AFCI/GFCI CBs? If so, which one(s)? I have never had any electrical issues.

  • 1
    At $40 a piece, this could be a few thousand dollars in breakers. That investment would have to come with a good reason.
    – JPhi1618
    Sep 27, 2019 at 19:52
  • Why ask us? You have access to a licensed master electrician...
    – Solar Mike
    Sep 27, 2019 at 20:57
  • 1
    @Solar Mike-- because he lives out of state and is too busy running his business for me to bother him continually. He just happened to be visiting and mentioned as he saw my panel after having dinner one evening. So my 'access' is quite limited.
    – peinal
    Sep 30, 2019 at 12:07

3 Answers 3


An AFCI is more a protection from "fire issues" than anything you'd typically associate with "having electrical issues."

NEC allows use of NM cable in residences. NM cable is sadly prone to being gnawed at by rodents, and rodents are sadly prone to be in houses, even nice ones. Some folks estimate that a human is rarely more than 15 feet from some form of rodent (mouse, rat, squirrel etc.) I've seen multiple-feet-long sections of NM cable gnawed back to copper in remodeling jobs, and those were live, operational, and not having any electrical issues - because the copper had not touched the next bit of copper in the cable yet. IF a solid connection was formed between them, you'd expect a breaker to trip. But if something not as robust made a connection, you could get a hot plasma carrying current between the conductors without necessarily drawing more current than the breaker was rated for - and that hot plasma can set anything combustible on fire.

An AFCI is looking for the "signature" of a plasma discharge, and some of the early ones were rather terrible at discerning the difference between a fault and a brushed motor, which has tiny arcs between the brushes and the rotor. I believe they are somewhat better now.

People who should STRONGLY consider AFCI retrofitting when not required by scope of other work requiring code updates would be those with 15 & 20 amp circuits on the problematic old Aluminum wiring (1960's era, vaguely) that is a particular fire hazard, and those with other "very elderly and suspect" wiring. Lacking those signature items, consider it, sure, but how critical it is will be a personal call, possibly influenced by your level of thinking your house is utterly rodent-free or otherwise.

Other things can cause arcs, such as poorly done work (loose wire-nuts, using backstab connections) or the classic 'nail into a cable' when it does not trip the breaker.

  • Did you know you hit "community wiki" on that? Sep 27, 2019 at 19:53
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    Not like the rep does a thing past 25K. Yep, I know I did that.
    – Ecnerwal
    Sep 27, 2019 at 23:18
  • Rodents are common as we live in the country. Every winter we fight mice. So from that angle, I don't have any delusions...
    – peinal
    Sep 30, 2019 at 12:00

You've told us almost nothing about your house, and it's possible you wouldn't even know how to tell us what he is seeing.

On the one hand, there are certain reasons why such breakers can be a very good idea. One thought that pops into my head is aluminum small-branch-circuit wiring, which was supposedly used on into the 1980s. On the other hand, there are lots of experts who are all too happy to spend other people's money. A house with all AFCI and liberally splashed GFCI is certainly safer than a house without, but you have to balance that against the not inconsiderable costs of a panel full of them at $40 (AFCI) and $50 (both).

AFCI/GFCI is not available for "double-stuff" breakers (2 breakers 1 space), commonly used when a panel is over-full. The panel would need to be enlarged or external devices used.

AFCI protects against arcing, which starts house fires. It literally listens for that buzz-crunch sound you hear when hooking up speakers or headphones.

GFCI protects against ground faults, which usually shock humans but occasionally start fires. They monitor for current going some direction it should not, i.e. Through a person. GFCI compares the current on the hot and neutral wire; they should be equal.

Both of these protective systems can be sensitive to existing bad wiring. For instance, some houses have sloppy installation where neutrals are cross-wired between two circuits. This will cause current to be unequal on each circuit's hot and neutral, which will trip a GFCI. The real reason AFCI is now mandated in new construction is a lazy wiring technique called a backstab. These are notorious for failing "open" for no reason, or even arcing and melting the receptacle. These types of problems must be hunted down and fixed, or the breaker will simply trip and refuse to reset.

As such, this is a much bigger undertaking than merely slapping in two rows of AFCI/GFCI breakers and declaring victory.

Further, certain circuits should not be protected because you would create a race condition between two competing safety devices. A refrigerator's one job is to keep your food safe, and if grounded it does not benefit from GFCI protection. You don't want a useless GFCI trip spoiling your food. Similarly, you don't want to "protect" smoke detectors, fire pumps, radon removal systems, etc.

AFCI priorities

Historically, AFCI was recommended for bedrooms, because of one thing: Electric blankets. However, it was discovered how well they work on backstabs. So, to save Romex flingers $1 per circuit by using backstabs instead of screws, we must all spend $40 on AFCI breakers. golfclap

So here's my idea of an AFCI priority list.

  • bedrooms with electric blankets in use
  • Aluminum wiring
  • knob and tube wiring
  • any old, distrusted wiring (old means 1955, not 1995)
  • backstab circuits
  • circuits exposed to damage in accessed spaces in attics, basements, garages etc.
  • circuits outside in firestorm areas
  • circuits frequented by power strips, extension cords, or anything bought off the Alibaba/Aliexpress/eBay/Amazon sh*tstream

  • general circuits that run inside the house

  • NOT circuits in metal conduit

  • NEVER fridge freezer other safety devices on dedicated circuits

GFCI priorities

This is all about life safety.

  • Dockside on a lake, pond or river, OMG
  • Dockside
  • Dockside
  • did I mention, dockside
  • Hot tubs, pools, anything like that
  • Kitchens
  • Bathrooms
  • Anywhere you'd plug in an electric lawnmower
  • Everything on the first floor of a building that is expected to be flooded every 100 years, think Houston. It goes without saying the service panels would be on the 2nd floor.
  • anywhere within 6' of a sink
  • The usual NEC hit parade of garage, laundry room, basement
  • Everywhere else
  • NOT large metal-chassis appliances that are grounded whose cords and plugs are rarely disturbed
  • NEVER fridge freezer other safety devices on dedicated circuits
  • I thought refrigerators were required to be AFCI protected since the 2014 NEC?
    – Nate
    Sep 28, 2019 at 4:15
  • 1
    @Nate not if you're grandfathered. Which OP is. You should use any viable strategy to justify NOT putting fridges, freezers, smoke alarms, fire pumps, radon vents, etc. on AFCI. That guy with the Pushmatic panel, I would keep that old panel around just for that purpose lol. Sep 28, 2019 at 4:18
  • Refrigerators seem to be on a different level with safety equipment, which this requirement has always seemed wrong for. I admit it's a huge inconvenience to lose food, but... It won't literally kill you, unless you eat that spoiled food to spite your AFCI.
    – Nate
    Sep 28, 2019 at 4:22
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    @Nate I used to think that. Then I watched an aide spoon-feed my disabled mom cereal with 2 month old curdled milk. I have also watched aides feed my friend's developmentally disabled child. The old, young and sick have 3 things in common: a) others feed them untasted food, b) they can't communicate distaste or distress, which multiplies with c) their health/immune system is compromised so food poisoning can, in fact, literally kill them. An aide could potentially feed a helpless person bad food for days, not connecting it to their worsening symptoms. Sep 28, 2019 at 4:31
  • @Harper-- The home is completely wired with12 awg copper except for 240V circuits for water heater, stove, heat-pumps, A/C, pool pump. Anything with a motor has a dedicated circuit (dishwasher, washing machine, bath exhaust fans, kitchen exhaust fan. fridge, freezer, microwave) except ceiling fans. What else would you like to know? He did not see anything 'alarming'--he just recommended replacement to be 'up to code'. I' having a hard time justifying $2K or more in new breakers when I have had no issues in the past.
    – peinal
    Sep 30, 2019 at 11:56

AFCI and GFCI protect different problems. Broadly speaking, AFCI is for fire protection from faulty connections or punctured cables and GFCI is for life-safety protection from ground faults. Personally, I would consider GFCI the bigger issue as it primarily protects from problems in devices (typically small appliances) which can happen to anyone at any time. The good news is that GFCI can be added very easily at point of use - i.e., the first receptacle in a string of receptacles in a kitchen, bath, laundry room or other area. The emphasis is on areas where things get wet, because that is the most dangerous environment to have a ground fault.

Check your receptacles, particularly kitchen & bath for TEST/RESET buttons. If you have TEST/RESET buttons then you already have GFCI protection and there is no need to waste money on replacing those breakers. If you don't have them, you can generally install GFCI receptacles at the first location in each circuit. Installation should be straightforward, provided you understand Line/Load.

Short version of Line vs. Load: Line is from the breaker. Load goes on to other receptacles (or lights or whatever). So pick the location and open it up. Disconnect the wires and determine which pair of hot/neutral goes back to the breaker. Connect that to the Line side of the GFCI. Test the receptacle and the TEST/RESET function. Then connect the other wires to the Load side and make sure everything else is working.

  • 2
    I wouldn't say load goes on to other stuff. I would say load goes on to other stuff you want GFCI protected, which should be a conscious choice for a variety of reasons. Sep 30, 2019 at 15:42

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