You need a AFCI in most places now. In the 2020 edition of the NEC®, Section 210.12 requires that for dwelling units, all 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas shall be protected by AFCIs.

The latest National Electrical Code requires both AFCI and GFCI protection only in kitchens and laundry rooms, but if you're already doing AFCI, why not do it all everywhere as it is clearly to be required at some point

Main downside is they are expensive. I've recently installed a new 24-slot subpanel and I'm using them everywhere required. At $50 a pop, that's a quick $1200.

Some countries you have a single one for the whole building, rather than one per circuit.

That dramatically lowers the cost.

The only real downside is that if you accidentally put your finger in the toaster, rather than just the power to your kitchen cutting off, the power to the whole house cuts off. I think thats a fine tradeoff to save $1200.

Well, if the power shuts off and that saves me from electrocuting myself, I couldn't care less how much of the rest of the house lost power.

The annoying part is when I plug in some faulty device that is not immediately dangerous and that shuts down power to the whole house.

> The annoying part is when I plug in some faulty device that is not immediately dangerous

Do you mind, re-reading that statement? I don't even understand that argument. You should not be plugging in faulty devices in the first place...

I guess you don't know if it's faulty until you try to use it. Manufacturing defects are a thing, but kind of a once every 30 years type thing, so maybe not a big deal to worry about. The reason you install circuit breakers and AFCIs is to avoid a fire in these cases; rare, but worthwhile to avoid.

Also because plugging in faulty devices into outlets is something that ought to be safe. Because with probability 1 it will happen in every house. If the way the house is wired makes the only safe action to shut everything off that's the problem and shitty wiring.

Exactly: it's just like computer OSes. You should be able to run a faulty program that divides by zero or dereferences a null pointer without the whole computer crashing. The computer should flag the error, tell you what went wrong and why, and let you continue with your work and the other stuff going on in other windows.

Fault-tolerance is an important and useful thing.

Of course I should not be plugging in faulty devices. But sometimes appliances that were fine before break down, perhaps some insulation broke down or just the ravages of time.

I would absolutely like that to be safe. And like I said, if it's immediately life-saving, then I don't mind the power to the whole house being cut. But if it's "just" a bad appliance, then, well, I do find it a bit annoying that it reset all my electronics, and I would have preferred it if only that specific outlet was effected.

But I would still very much like the protection.

real downside: many things work poorly on gfci stuff. E.g. A miter saw or welder. I had AFCI/GFCI breakers in my garage per code, but essentially no power tools work with those kinds of circuits.

I've noticed the same thing with a cheap lemon juicer in the kitchen. I'm assuming the brushes on the DC motor are the cause.

The bigger downside is nuisance tripping because the breaker doesn't like electrical noise emitted by some device or another in your house. I don't have any AFCIs but I've heard it's pretty common.

You'd rather have one circuit go out instead of the whole house, and if all you have is the one AFCI breaker you're going to have a much harder time identifying what device(s) is the culprit.

I've mostly used them on new circuits, but have put them on a few of my older circuits too. For my small sample size, I've yet to have one nuisance trip.

Yeah I've replaced all of the breakers (to living areas) in my 90s home with AFCI ones. Haven't had any nuisance trips. If I had "nuisance trips" I'd be more worried about my wiring than about my breakers...

This nuisance tripping is the bane of my electrican friend's professional life.

"Oh just err on the site of extremely cautious and sensitive. More safety can't be a bad thing."

And god forbid you use anything with a brushed motor, which has sparks in its normal operation

Some OS's have a single task for the whole computer, rather than one per application.

The only real downside is that if your app accidentally dereferences NULL, rather than just your application crashing, the whole computer crashes.

... Sorry, somehow reminded me of the early days of the Macintosh's OS before it was "true multitasking" (as the Amiga kids would love to tell us).

Don’t even get me started on AFCIs. At least the behavior of GFCIs is well-defined.

The AFCI thing is a money grab.

why's that, is there some guarantee they fail to live up to? Is there something probabilistic to them or something?

GFCIs have a simple and well defined function. What is the current through one lead? What is the current through the other lead? Do they differ by more than x amount? If so, trip.

AFCIs are a whole different thing - the plug is trying to predict when arcing is happening somewhere downstream of it and it has very little in the way of 'processing' power to do it, so generally there is a classical filter that is designed to detect the characteristic harmonics of the current waveform that are inherent to an arcing condition. When you experience a sharp upward or downward step in power draw you introduce harmonics, when you have capacitive coupling between SMPS you introduce harmonics, motors often introduce harmonics, etc.

There's like a zillion things that can create AFCI trip conditions and cause spurious trips and frustration for users, and there's very few documented cases of them doing the thing they're supposed to do. I think it's a case of someone being well intentioned but releasing regulatory guidance to use a product that isn't quite there in terms of technology maturity.

AFCIs are just The Man trying to stop us running Tesla coils.

Agreed on AFCI circuit breakers! They are now mandatory for all 15-20 amp light and plug circuits on new construction where I live - although breakers for large appliances do not require them. But I have several portable tools (eg a carpet cleaner) which will make an AFCI breaker trip every time. AFCI circuit breakers seem to be more fragile (read the box: much smaller range of acceptable heat and limited number of duty cycles) - I apparently killed one just by tripping it repeatedly. And while a regular 15 amp breaker is a few bucks, the CAFCI breaker I'm supposed to use is $45...

They highlight bad appliance design especially hard, while also being somewhat difficult to pinpoint due to the design of many electrical systems.

Arc detection is also basically somewhat complex RF processing, so there are multiple approaches to it and implementations vary.

Plus (detected) arcs are common with for example brushed motors.

Maybe there's something else the person you replied to would like to highlight, but I wouldn't call them a money grab, just made difficult due to some past choices.

AFCI's are of dubious effectiveness at their purpose (preventing fires). They're kinda snake oil because each manufacturer won't tell you under what exact conditions they'll trip. Somehow the law in the USA now requires them on every circuit, although they aren't used at all in Europe (which has a higher voltage yet far fewer electrical deaths).

FWIW, Google says 540 electrical deaths per year in Europe vs. 200 per year in the USA. Whether that's from lower voltage or more GFCI is anyone's guess.

Europe is many different countries with different electric code

That’s definitely lower voltage. It’s just physics.

AFCIs aren't meant to protect against electrocution, just sparking which leads to a fire.

I'm not sure where you are getting this.

According to the CPSC, who analyzed some 10s of thousands of fires, something like 50% of them were caused by wire arcing that could be prevented with AFCI breakers. This is the exact reason why the NFPA is moving the NEC towards eventually requiring AFCI on every circuit in the house.

Key word is could.

Do AFCIs actually do their prescribed function effectively?

There are other downsides. For example, actually finding a two-pole or AFCI breaker or, worse, a combination AFCI/GFCI breaker is not so easy.

I recently installed some new circuits and was able to find them, but strangely it was $20 or more per circuit cheaper to get an AFCI/GFCI outlet and a regular breaker instead of combo breakers.

it is nearly impossible, IME. Good luck finding AFCI 20amp 2 poles for doing shared neutral 120v circuits on a 14/3 wire.

"At $50 a pop, that's a quick $1200."

See, this is the part I hate. I bet someone patented the design, then the NEC made it mandatory, and now they just rake in the money on something that likely costs <$10 to make. If something is legally mandatory, it should not be patented.

Looks like you're not wrong: https://patents.google.com/patent/US9577420B2/en

Michigan is an exception. No AFCI required.

AFCI trips on the smallest thing. Turning on my blender or microwave tripped it. I ended up downgrading to just GFCI in frustration.

Brushed motors in particular are largely indistinguishable from an arc fault. Lots of home motors (in vacuum cleaners, fans, blenders, food processors, garbage disposals, blah blah blah) use them.

Not an electrician, but an observer of tradespeople at r/electricians.

There are definitely bad feelings about these AFCI breakers. The feeling is that the code mandate for AFCI got out front of the reliability of actually-produced AFCI's, and actually-in-use products like blenders that may have small "arcing". This results in expensive call-backs from unhappy customers who are getting nuisance trips.

Is there a site that show what states have adopted what version? looking at my states webpage the official adopted code for my state is NFPA 70 - National Electrical Code, 2008 Edition.

They only need to be installed in specific places... But they ought to be installed for the whole house.

You do want your refrigerator on one. What when your mom is putting a metal saucepan into the fridge of leftovers, knocks and smashes the lamp inside, and the AC lamp power supply kills her though the metal saucepan?

What when a baby puts a fork into an electrical outlet in the living room?

What when floodwater comes in and kills everyone on the ground floor of your house while you are frantically wading in the water trying to move furniture upstairs?

There are plenty of times you want a whole house GFCI.

Let know when GFCIs and AFCIs are robust enough against spurious tripping and I will readily install them everywhere.

GFCIs are notorious for tripping on certain appliances like refrigerators and freezers, and can trip due to RFI from other devices in the house.

AFCIs do not like anything with a brushed motor, especially power tools and sufficiently large vacuums.

I have personally experienced all of these just in the last couple years.

European GFCI's are 30mA, and don't false trip. US GFCI's are 5mA, and frequenty false trip.

lots of info here[1]

TL;DR: The US regulations prevent small electrical faults into things like swimming pools from causing people to drown. The european regulations will stop you getting killed by electricity directly, but won't stop you drowning if you happen to be in a pool while touching some wiring.

[1]: https://diy.stackexchange.com/questions/218700/why-are-usa-c...

This thread is really baffling to this Dutchman. All houses have a house-wide residual-current device here; it is not a topic for debate at all. And indeed, these don't false trip.

US electrical wiring always weirds me out. Cables run through walls without pulling them through hard plastic conduits and sockets that look like something designed seventy years ago. It's probably a matter of perspective, but it seems like such a completely different approach.

Those hard plastic conduit are not providing much in the way of mechanical protection. wires in studs works pretty well, really.

Whole-house GFCI is a good thing, but we should be careful to consider what you get for that. In order for GFCIs to coordinate the whole-house device is going to trip at a relatively high current. This is definitely on the edge of what will disrupt the heart of a person. American GFCIs are often at the device level on the outlet, so they are more error prone in terms of spurious trips but they are also much, much safer because they are substantially more sensitive.

GFCIs also have a lifespan. Ideally they’ll be easily replaced at the breaker panel, but most of the time they are put on outlets. Those outlets could be in a difficult to reach location. They are about twice the cost of a regular outlet/breaker. AFCIs seem to be about three to four times.

If the system voltage is between 150 V and 300 V, then either double insulation or a separate safety ground with the same gauge wire as the hot conductor is required; the purpose of the safety ground is to keep the equipment case or cabinet from reaching 150 V in case of a fault.

In this case a Class C GFCI may be used to provide fibrillation protection, let-go-protection is optional.

A Class C GFCI is 20mA trip current.

This will not spuriously trip your freezer. If you're having issues with this it's because you're designing your power distribution system incorrectly.

I have twice lost a fridge full of food due to spurious GFCI trips, once when I was a recent graduate and it was a painful experience financially.

I now make sure my fridge/freezer is NOT on a GFCI. I'll take my chances of getting a 120VAC shock from my fridge [which is attention-getting, but very unlikely to be injurious].

Also funny how fridges are required to have their own circuit, but newer fridges are increasingly vfd/inverter drive, and don’t have surge power draws anymore. They use a few hundred watts continuously and that’s it.

I’d be more quickly to find out my fridge died if the lights in the kitchen stopped working.

Not sure why fridges don’t just have a battery-powered alarm that goes off when the temperature gets too high for too long.

I have a lot of power surges in my area. Recently, the old power shut off, then power back on in 3 seconds thing happened - and the surge was enough to pop my fridge motors and cause a $900 repair.

I upgraded them to not only a surge protector, but this little neat shut off device. It's a device that goes between the fridge and the wall outlet, and basically if for any reason this device loses power - it shuts off the power to the powered device for a minimum of 3 minutes. This way the power can blink 100 times in 3 minutes, and my fridge won't have to eat 100 surges. It will just happily sit off for 3 minutes, and then come back on.

Can you share what device you're using for the 3-minute shut-off and recovery?

I have this guy

https://www.amazon.com/gp/product/B00D7KP8S4

But am not partial to this brand or anything. But it seems to do what it says it will do.

What kind of fridge do you have that draws several hundred watts continuously? I haven’t tested my fridge, but I have a very large chest freezer that never draws more than ~35W. Surely a fridge can’t be 10x worse than that.

I seriously doubt that your freezer max draw is 35W. An Energy Star freezer can only average ~25W across the entire year. I doubt that the peak is less than 1.4x the average draw.

A fridge max power draw is usually during the defrost cycle. My defrost heater measures a bit over 500W.

You’re probably right, but I did watch my freezer plugged into a kill-a-watt for a while, and even when the compressor first kicked on, I never saw anything higher than 35W. Maybe the kill-a-watt is inaccurate, or maybe it doesn’t update fast enough, I’m not sure. Another factor, too: it doesn’t have any sort of auto defrost.

Different models and different designs and everything, but just as another data point, I recall my chest freezer pulling 300W+ when the compressor kicks on, and likely higher transient spikes, as it kept burning out the fuse on my 500W transformer, and I had to switch to a 1kW one.

Check out the YoLink temperature sensors on Amazon. They are amazing for monitoring our secondary freezer. All their sensors have been great. Temp for fridge/freezers, leak detectors, temp+humidity for basement, they have a motion sensor that is a magnet you can place in the back of your mailbox if you want to know when mail is delivered. Their door sensor can be installed on overhead garage doors by a magnet and a velcro strip for the part that goes on the wall. They also have a 1/4 mile range and the sensor can be inside your fridge/freezer and still connect. App is great, no monthly fee, you get notifications on your phone you can also get a small number of SMS messages for free. All notifications/limits are configurable.

A shock on 120VAC can absolutely kill. It’s not the volts which kill you, it’s the amps, and it’s specifically why GFCI trip at somewhere between 5mA and 30mA (depending) — it’s because those are not levels as likely to cause fibrillation.

My mom doesn’t live with me (the bulb inside the fridge is LED anyway), I don’t have a baby (babies don’t carry metal forks), and I live on the second floor (but the power would be out long before the first floor floods).

I don’t want whole house GFCI.

I agree that over-zealous GFCI is annoying. BUT, as a new parent, I can assure you that babies will manifest dangerous objects and do dangerous things.

> I don’t have a baby (babies don’t carry metal forks)

Your second claim could only be made by somebody for whom the first statement is true.

A whole house GFCI would ruin all the food in my refrigerator several times a year.

> You do want your refrigerator on one. What when your mom is putting a metal saucepan into the fridge of leftovers, knocks and smashes the lamp inside, and the AC lamp power supply kills her though the metal saucepan?

Your fridge scenario is.. fantasy. What is the path to ground? There isn’t one.. you can hold onto a live phase conductor all day and not get shocked if the circuit isn’t completed.

Refrigerator only needs a GFI if it is within a certain distance of a sink.

> What when a baby puts a fork into an electrical outlet in the living room?

The NEC requires tamper-resistant receptacles in all dwelling units.

Also re: flooding and GFIs, all basement receptacles need GFI protection due to flood risk.

Yes, the pan would complete the circuit. Not to mention the whole scenario being extremely unlikely.

> Refrigerator only needs a GFI if it is within a certain distance of a sink.

Not anymore. NEC 2023 requires GFCI for every 120 or 240V outlets in the kitchen, regardless of their location or proximity to the sink. This was a big change.

Oh I wasn’t aware of that change, my state hasn’t adopted NEC 2023 yet and I haven’t received my NEC 2023 code book from my employer yet.

It’s a negligible cost change for new construction, AFCI breakers and AFCI/GFCI breakers are the same price, at least for Square D 120v 15A 1P

My understanding is a GFCI is an American term for an RCD or an RCBO?

My (UK) fridge is on a standard 30A breaker which itself comes off a single 80A/30mA RCD which was presumably part of the regs at one point. It's never tripped. All the RCBOs I've seen are 30mA too.

(I have some sockets on a 10A breaker downstream of this which have tripped - the house needs a total rewire, total bunch of bodge jobs from the previous owner, including a 13A socket in the bathroom)

Does a GFCI typically have a lower trip that 30mA?

Yes. USA GFCI's are like RCD's, but trip at 5mA. Thats why they false trip pretty often.

It's funny, In was doing a huge renovation once and during the work my refrigerator had to be plugged into another outlet that happened to be GFCI. We had to be very mindful about making sure power was flowing. Sometimes, certain combinations of things being on at the same time would trip it. It was an old house with only 100A service and who knows what with the wiring.

> In the U.K., you just can’t have plugs in bathrooms (aside from the shaver plug),

Disclaimer: I'm not an electrician

My understanding is that is not entirely technically correct.

You can have standard sockets in bathrooms in the UK.

But, and it's a big BUT, 99.999% of bathrooms in the UK are not big enough to be able to place the socket 3m away from the relevant wet "zone" (shower and/or bath and/or sink, IIRC).

However, IIRC, shaver sockets are OK, as are spurs. Irrespective of bathroom size.

You’re correct, bathrooms in UK are zoned and most houses aren’t big enough to meet the distance requirements from the “wet zones” to accommodate a regular socket/outlet.

Shaver sockets are typically going to have ingress protection.

https://www.tapwarehouse.com/blog/how-to-guides/understandin...

> I do not want my refrigerator or computer on a GFCI

Why not? Here in Belgium they are required everywhere and that works just fine.

Whole-house GFCIs are far less sensitive than the GFCIs built right into the receptacle.

That does not explain why you wouldn't want a GFCI? It's not like you can't chain them.

Because they trip much more easily, and they are sinply not needed all the time. Plugging a motorized refrigerator full of perishable food to a GFCI receptacle is a bad idea.

I used to work on residential construction jobsites and the only power on-site would be a pair of GFCI duplex receptacles in the basement beside the panel. Tripping the actual overload breaker was rare (and usually only happened when multiple people were running off a single extension cord), but the damn GFCI breakers on the receptacles themselves tripped all the time, particularly when the table saw was running at full tilt for 20 minutes straight. They're just too sensitive for certain applications. Now, you can buy combined overload/GFCI circuit breakers for in the panel, but they're ridiculously overpriced so no one uses them, and they're probably just as sensitive.

America has 110 V which is more of a nuisance than a threat when it’s dry. Our GFCIs are specifically for wet applications (like bathrooms) and so are much more sensitive than European GFCIs.