First off. The only way to provide proper "grounding", is to install a grounding conductor from the panel to each outlet. Providing AFCI and GFCI protection to the circuits is helpful, but these devices will not provide "grounding".
If you switch from 2-prong receptacles to 3-prong on these circuits, you should not connect anything to the grounding screw of the receptacles. You should also (technically) install labels at each outlet that read "GFCI protection" and "No Equipment Ground". Though, these labels aren't common in residential situations.
- Replace GFCI breakers with CAFCI breakers and add GFCI receptacles to the first-outlet on each circuit.
This is probably going to be your best bet. In this scenario, the CAFCI breaker provides protection to the entire circuit. The GFCI protection being at the first outlet, means that while the wiring from the panel to this location is not protected, the rest of the circuit is protected.
- Keep GFCI breakers and add AFCI receptacles to the first-outlet on each circuit.
This isn't a terrible option, although the AFCI device will not be protecting the wiring between the panel and the device. Also note that an AFCI device only detects line to ground arcs (parallel arcs), while a CAFCI device detects both line to ground and line to line arcs (parallel and series arcs).
- Replace GFCI breakers with Dual Function AFCI/GFCI breakers.
If you could actually find these (and could afford them), this would probably be your best course of action. Unfortunately, these devices probably don't exists (yet) from most manufacturers.
There's more going on here than you think.
In the bad old days, all we had was the plain old thermal-magnetic circuit breaker (or worse yet, thermal-only fuses for folks with old stuff). Folks got zapped by hairdryers dropped into bathtubs and watched as poor connections and damaged cords turned their house into a bonfire for the local FD.
In the 70s, as microcircuit technology developed, the Ground Fault Circuit Interrupter was introduced. These devices use electronics along with a current transformer to measure the difference between hot and neutral, and open the circuit if it is excessive -- in the power distribution world, the equivalent function is called a "differential trip". UL set two trip thresholds for these devices -- 6mA for protection of personnel (the GFCI we find in our bathrooms), and 30 or 100mA for protection of equipment (a so-called Ground Fault Protector for Equipment, or GFPE, device). The GFCI was made available in both a receptacle form factor, originally intended for "quick fix" retrofits, and a circuit breaker form factor, originally intended for new construction or GFCI applications outside the scope of 15 and 20A receptacles. GFPEs, however, were only made available in breaker form as they are used in a limited set of applications, mainly to protect long heating cable/tape runs or high-powered feeders where ground faults can cause serious fires.
Fast-forward 20-odd years now, into the late 90s. Microcircuit and microcomputer technology has advanced significantly, and GFCIs have become a well-known part of house wiring, deployed in a variety of wet and damp location applications. Dropping a toaster into the bathtub becomes futile as an assassination method. However, houses are still burning down from electrical faults, aggravated by postwar copper shortages causing AA-1000 wiring and steel screws to be pressed into dwelling unit service for a time in the 60s (aka the aluminum wiring debacle). However, the use of GFPEs on high powered feeders has proven to be a successful fire protection measure in that arena, and some testing performed by CPSC and UL revealed that damaged cords and wires were a major problem for house fires.
Enter the first generation Arc Fault Circuit Interrupter (AFCI). These devices were based on a mixture of analog and digital technologies, and proved highly effective at detecting house-burning parallel arcs, but in order to detect other fire-starting conditions, such as glowing connections, they also had to add the equivalent of GFPE protection into the device. While not enshrined in the UL standards for AFCIs (a rather...debatable requirement for "series arc detection" was substituted for it, at least for the combination type AFCIs commonly deployed), most AFCI makers incorporated this functionality into their devices. (Branch/feeder AFCIs lack series arc functions, relying solely on the GFPE trip to provide protection against glowing connections and other leakage inducing faults.)
However, the AFCI/GFPE combination had a drawback -- people were expecting it to behave like a regular single pole breaker, not a GFPE, and were perplexed by mystery trips when they started installing it. While some of these mystery trips were due to arc-generating devices not being distinguished from real arcs, or EMI, some of them were a function of shared and looped neutrals in house wiring as a result of wiring errors. This, of course, was all blamed on the AFCIs, rightly or wrongly, and also led to GE eventually redesigning their AFCI products to remove the GFPE functionality, replacing it entirely with microcomputer-based series arc detection.
Fast forward another 10 years. The AFCI requirement, while still debated at the local level, has become permanently enshrined in the NEC, and is being expanded much like the GFCI requirement was back in the 80s. One spot AFCI protection was expanded to during this was the kitchen -- with high power appliances, extensive usage, and all sorts of cord damage possibilities, the possibilities for electrical fires abounded here. This, however, collided with the existing requirement for GFCI protection -- you either had to put one of the protection devices in a receptacle form factor (usually the GFCI), or use a subpanel to house a second, series-connected breaker with its attendant hassles. Hence, in the early 2010's, manufacturers started to introduce Dual Function Circuit Interrupter (DFCI) devices that combined combination-type AFCI protection with GFCI protection for personnel. While only available for single phase, 15 and 20A branch circuits at this time, they represent the ultimate in protection.
Furthermore, receptacle (called "outlet branch circuit") AFCIs were developed for retrofit and other limited (such as part of what is called a "system combination AFCI" using a specially listed circuit breaker, supplemental arc fault circuit breaker, or branch/feeder AFCI) applications. There is even a receptacle DFCI on the market, but its application scope is unclear.
Can you have more protection than the bare minimum?
The answer to this question is almost a resounding yes. The main caveats with installing AF/personnel GF protection throughout a building are leakage currents, EMI, and shared neutrals/MWBCs. Once these are licked, then full ground and arc fault + overcurrent and short circuit protection throughout a building can be a reality.
First, some appliances have poor AF/GF compatibility. They generate arcs internally that are mistaken for arc faults, spit EMI onto the power line that confuses sophisticated trip sensors, or simply leak too much current to ground. Once again, though, instead of taking, say, the vacuum back because it's tripping the arc fault breaker for their bedroom, people blame the breaker for the problem -- this has been a cause of serious pushback against AFCI mandates, and is even a problem with plain GFCIs in corner cases.
The other problem is shared neutrals and MWBCs. Shared or looped neutrals are the result of common wiring errors, usually "nut all the whites together" in boxes which are fed by more than one circuit. A simple solution is to keep separate circuits completely separate, but this isn't always practical (say for kitchen small appliance branch circuits). Fortunately, another option is available -- nowadays, you can buy two circuit (/2/2) NM cable that has two distinctly identified neutral wires in it, which can help with this, and also provides a suitable substitute for the use of MWBCs, as two-pole DFCIs are not available despite two-pole AFCIs and GFCIs being stock items.
Best Answer
The question presumes something I do not believe.
I don't believe all AFCIs also do GFCI at 30ma level.
This answer here is a very well-informed and interesting exposition on how many AFCIs were given a "weak" GFCI function to detect arc faults to ground. But this was less than ideal - not least it requires you make a whole line of 2-pole AFCIs; in most of those applications, handle-tying two 1-pole AFCI would suffice if the AFCI didn't need to do that GFCI-ish thing.
This lesser protection was typically 30ma. Remember, 30ma protection is inadequate for kitchens, garages, basements or anywhere else NEC requires GFCIs.
Some people believe AFCIs are required everywhere GFCIs are not. The NEC does not say that. If your local inspector says so, you need to have the discussion with them. You can fight city hall, but it's cheaper to just replace that problematic fridge.
Refrigerators are not the use-case for AFCI or GFCI
GFCI is to protect people from shocks, typically from lightly insulated plastic gadgets getting broken or wet, or the user having contact with an energized part of a 2-prong tool. This is absolutely irrelevant to an immovable box with a steel chassis, all the 120VAC gear inaccessible at the bottom rear, and a fully plastic inner lining. It would be nigh impossible for a consumer to contact anything 120V if they were trying.
AFCI is to prevent fires from wiring faults either in house wiring or in plastic, flammable devices. Being entirely contained inside an all-steel box, it's nigh impossible for a wiring fault inside the fridge to start a fire without also pulling enough current to trip the breaker. Yes, the cord, receptacle or in-wall wiring could have a problem; but consider the same logic that is applied to the NEMA 10 receptacle: this is fixed equipment with a typically inaccessible receptacle, which is rarely unplugged or moved.
Sometimes, a ground fault trip is a ground fault
I do see a lot of forum posts like
Sometimes, a GFCI trip is exactly what it says on the tin -- "working as intended" genuine trip caused by faulty machinery. Often cleared by a good cleaning, but sometimes, you just need a new fridge. Insulation failure is one way machines fail.