Are toasters really electrified inside of the "slots"?

I'm just going to respond to the "How could they possibly sell a consumer-oriented product like that which zaps its users if they happen to touch the interior slightly?" part of your question.

If you open and read the User Manual for the toaster you'll see plenty of warnings about not sticking metal objects into it, not to drop it in a tub full of water, not to stick your finger in when the elements are hot, and many other legal disclaimers. It may also come with a tag on the cord with warnings to the same effect. The User Manual will also probably say something like "Please read this Manual in full before using this appliance".

Now practically nobody bothers to actually read that kind of manual, and most people throw them straight into the recycling bin, but by putting those instructions and warnings there they are no longer legally liable for their customer's misuse.

You could similarly ask, "How could they possibly sell a blender which cuts people's fingers off if they happen to touch the blades slightly?", or "How could they possibly sell a range top which burns you if you happen to touch it slightly?". The answer would be the same for all of them, they are equipped with warnings and instructions, and not following those instructions can be dangerous.

A toaster is simply a length of nichrome wire put across the mains power, which will be 120 or 240 VAC, depending on your country:

Those red-hot wires you see in the toaster? That's the nichrome wire.

If you stick a knife in the toaster and it contacts the nichrome wire, you're making a potentiometer:

By inserting the knife at the appropriate location, you can select the degree of electrical shock you desire: anywhere from none at all to the full shock potential of the electrical socket.

If the toaster is off, both sides of the circuit could be disconnected:

But who knows, one of the switches might be faulty, or the toaster may switch only one side for reasons of cost. Only one switch needs to be open to shut down the heating element, but if SW1 is closed then the heating element remains at 120 or 240 VAC. Once you complete the circuit with a knife the toaster will resume toasting and you will have a bad day.

A RCD or GFCI is required for all new construction in kitchens in pretty much any part of the world these days, which might frustrate your attempts to make toast by this method. But it could be faulty, your kitchen could be too old, or you could live in a part of the world that doesn't enforce these things too much.

The reason for the old trope about forks in toasters, that none of several answers already posted seems to have captured, and this is really irking me, dates from old electric wiring standards.

The heating element of a toaster is of course supposed to be connected to the hot — errr, "energized" wire of household current. When the toaster is off, the heating element is disconnected by means of an internal switch of some sort, and quite safe to touch, presumably.

But electric sockets in US houses before the 1960s were very commonly ungrounded, unpolarized, two-prong NEMA 1-15R affairs. Whether that internal switch disconnected the hot side of the circuit, or the ground side of the circuit, was a matter of whether the toaster was plugged in "correctly," and that was a 50/50 proposition, since the plug and socket were both symmetrical and unmarked.

A modern toaster, plugged in to a properly grounded socket, is probably reasonably, I mean don't do it, but there's a good chance you won't be injured. Sticking a fork into a toaster in the 1950s was a bad gamble.

When it comes to safety, we typically give stories that provide a wide berth. The truth is, one end of that glowing filament is at 120V AC, while the other is at 0V. Which one is which? There's no visual way to tell; they glow the same. If I had a multimeter, I could tell you. Or if I could disassemble it and could trust the wiring of the house, I could tell you. In the end, its a 50/50 chance on your life. Why risk it?

Now I know a bit about electricity, and could probably pull it off. But I know enough about electricity to respect it and not mess with it unless I had a good reason. If I was in some warped Austin Powers film where someone had to stick a knife into a toaster or some Rube Goldberg mechanical contraption was going to kill someone, I could probably find a way to do it safely. Am I going to do it just because some toast got stuck? No. I'm going to respect the electricity more than that. I'm going to unplug the toaster, and then mess with it. Preferably with something non-conductive like wood just in case the toaster had a capacitor in it for some reason which could hold onto a charge.

On a related note, mechanics who work on cars typically don't wear their wedding ring while working. Even the 12V battery in a car can generate some nasty burns if you don't respect it enough. Mechanics know that there's a chance that, one day, they won't be paying attention and might bridge the 12V line to ground. So they respect that battery enough to solve the problem before it becomes one.

Also on the same vein, in the US we have to teach our children not to stick metal objects in power outlets. They're all at kid level. Some nations have more advanced outlets. Some will even keep a plastic sheet slid over the hot line until after the grounding plug has reached far enough into the outlet to be pretty certain that there is, indeed, a proper plug being plugged in, and not a paperclip. I'd say I had about a year where I really wished we were living in one of those countries.

Yes.

I suspect what you are wondering about is how that a toaster compares against an electric stove burner, where you can, indeed, touch (well, I mean touch with a long, metal object, because of the heat!) the burner's cooking surface without receiving an electroshock.

The difference is in the case of the stove burner, it is a similar conductor as well, but it is wrapped in ceramic which is an insulator. This is both specifically to avoid making it an electrocution hazard (due to the often employment of metallic cookware), and to make it sturdy enough to hold the weight of cookware upon it because metals soften greatly once hot enough to glow visibly red (hence why you heat them to such temperatures to fabricate metal parts, and also why the Twin Towers collapsed on 9/11). In the case of the toaster, however, those are bare conductors, typically made of a "nichrome" alloy which gives a low enough resistance to get red hot under mains voltage yet not so low as to draw so many amps you blow the house ($P = frac{V^2}{R}$, so if you have $V = 120 mathrm{V}$ and want $P = 500 mathrm{W}$ you need an $R$ of $28.8 Omega$ at working temperature. The drawn current $I$ will be ~4.2 A.).

Thus, they most assuredly will deliver current to your body, to the tune of a 120 or 240 V voltage drop, just like sticking a fork in a mains socket as, in effect, that's what they are - to make it as simple and efficient as possible you just drop mains voltage directly over the heating wires and let the properly-calibrated resistance of the element do the rest.

One may then wonder, well "why not build it like a stove, for safety?" Well, 1) because most people already know not to stick knives in there anyways as you are aware, 2) because that you will add thermal (and physical) mass to the toaster, which will make it all three of heavier, slower to come up to temperature, and more expensive. It's a great illustrative example of technology functioning as an element of culture in a very reliable way.

I just want to add to the already existing answers by providing a simple explanation of why the wires actually can't be shielded properly without loss of efficiency:

The toasting of the bread requires heat. Heat is created by electricity running through wires with high resistance, which converts the power into heat. This heat then travels through the air, passing the bars that are holding the bread in place. If you insulate the wires in any way, the heat produced by them cannot freely emanate through the air and onto your bread. Also, the usual way of insulating wires, which is covering them with e.g. rubber, wouldn't work for such hich temperatures anyway, as the rubber would just melt.

You could of course just change the bars holding the bread into a finer grid, but that grid could impair the efficiency and even distribution of the heat, and you could still stick smaller objects like needles through them. So the spacing and size of the bars are actually a compromise between how big of a metal object you can fit through to shock yourself and how much heat can pass.

Why would they have the metal parts responsible for pressing against the bread and keep it in place be having electricity going through it?

They don't. The metal parts responsible for pressing against the bread are not electrified.

The electrified parts are behind the wires which press against the bread. You can see them, touch them, burn yourself on them, and kill yourself on them because the wires which press against the bread are open, to allow radiant heat and hot-air convection, to toast the bread.

This separation of function is common for engineering materials. The wires which press against the bread are made of materials which are not good for heating: the heating elements are made of material which is not good for pressing against bread.

There is a kitchen device which heats material which is pressed against bread: it is called a Sandwich Press

The result of using a Sandwich Press, or an Oven, or a Fry Pan, or a Deep Fryer or a Wok, is not the same as that from a toaster, which is why we give those cooking methods and cooking devices different names. If you make a toaster which is a Sandwich Press, it is not a Toaster, and the result is not Toast.

I just to want to add a caveat here for people reading this who might read these answers and think the advice applies to all electrical devices. For a toaster, sure, turning if off and removing the mains power will render it inactive, however this does not apply to electrical devices with capacitors. Capacitors can hold a charge even when the device is unplugged and will cause a shock if you are unlucky enough to discharge it.

Overall, the best advice is to never touch a live electrical wire at all if you can help it, and to use insulated tools or PPE if you can't, plugged in or not.

How could they possibly sell a consumer-oriented product like that which zaps its users if they happen to touch the interior slightly as they stick a knife into the piece of toast bread to get it out from the toaster when it inevitably gets stuck sometimes? Or is too hot to use your fingers?

Consider your own perspective. This sentence shows an expectation on your part that the entire world be covered with “baby bumpers” to protect people from their own stupidity.

A non-cheap water boiler recently stopped turning itself off from just handling it a little too roughly, so if something potentially dangerous like that could happen so easily, maybe the toaster can also start leading electricity through its inner metal parts?

More of that assumption. “Handling a bit too roughly” means “smashed up”. I’m not sure what you’re looking for there. Indestructible stuff?

Notice how your earlier bit was an accountability shift: from “I am responsible for my actions” to “the world must anticipate my foolishness and protect me from myself”. Which is not a good road to go down, by the way.

And this chapter shifts from “I broke this due to my own carelessness and I am responsible to replace it”, to “the manufacturer is at fault for making it possible to be broken by me”.

That’s not a reasonable stance; if that actually had legal tooth, no one would manufacture anything at all.

I'm also interested in hearing if this was different for early toasters. Usually, things back in the day used to be very dangerous and scary.

There it is. The assumption that things used to be unsafe, and are now, safe.

What year, exactly, did you think things changed???

Of course they didn’t change at all. Everything that was dangerous is still dangerous. In 1933, people were sending their children to the railroad yards to pick up stray pieces of coal to burn in their stoves. Railroad yards are still just as dangerous; what changed is houses stopped using coal.

And there have been tiny increments of improvements for a century in 10,000 areas. Highways started to get guardrails to protect deadly cliffs. Then they got barrels to protect bridge abutments. Bigger roads got boulevarded to separate opposite traffic. Kitchens got GFCI devices, which pretty much put the kibbosh on toaster-knife fatalities and a variety of other kitchen-bathroom-pool-dockside accidents (where installed; older facilities grandfathered). Smoking is less common, which reduced bedroom fires. We have bodies like NFPA, NTSB, NHTSA, even BLM making a million small improvements.

I won’t deny there’s a nerfing effort, and some part of our economy is allocated to it.

But you are mistaking that for “the whole world being nerfed”. Not hardly.

I think what we’re really hearing there is a young person’s sense of immortality, or outrage at mortality?

But then again, this world is full of dangerous things, and maybe it's considered to be such a basic security knowledge...

Because education is an essential part. If you tell people “don’t do X”, then you don’t need massive infrastructural changes to protect them from themselves.

We’re seeing that played out, right now, with COVID-19. We have nothing to fight it with, except education. We can actually win it with collective intelligence. Some countries are.

It still seems odd to me. Why would they have the metal parts responsible for pressing against the bread and keep it in place be having electricity going through it? When asked, my mum just says that it "may easily get electrified" as if things like that just happen. But maybe she is right?

Tell you what. McMaster-Carr sells strip heaters as components, and they’re double-insulated. How about take a toaster, tear the offending exposed heater coils out of it (leave the toast lift), and replace them with double-insulated strips? And get back to us.

(Hint: the insulated toaster will be slooooooow.)

And by "inner metal parts", I don't mean that I've unscrewed it and taken it apart. I just mean the "insides"; the little hatches for the pieces of bread. The parts you can easily accidentally touch with a knife when you try to get the pieces of bread out from the oven.

You haven’t made clear why it’s necessary for you to poke metal objects in the toaster. There are 1000 safe things you could use, chopsticks, purpose-built toast grabbers, etc.

The only thing I can possibly come up with is that there is already a knife in your hand because you just sliced the bread and/or are about to spread jelly on it. That’s like owning a chainsaw rental and using Macs for the business PCs, saying you should be able to open the RAM access door using a chainsaw “because that’s what we have around here”.

Inside the toaster is a special type of wire, usually a nickel-chromium (Nichrome) alloy, that has a high resistance and lasts reasonably long at glowing-orange temperatures. It will be mounted on insulators, for a reason.

If you are using 120VAC, one end of that wire will be connected to the AC Neutral and the other end to AC Line, through a switch that closes when you push the lever down. So:

1. During toasting, a selection of voltages from AC Neutral (should be close to 0V, but without inspecting your house wiring I cannot verify that) to 120VAC is available on that wire.

2. Depending on whether only one side or both sides are switched: if the plug is upside down in the socket, or the AC wall plug is wired backwards (which is common, especially if a new DIYer has been at it; at least one receptacle was mis-wired in our home), the wire may be at 120VAC when NOT toasting.

Unplug the toaster, THEN poke inside it. Avoid damaging the wire.

Yes, and no. When the toaster is actually toasting, then obviously there's electricity running through the elements, which need to get hot (and will be seen to glow). Once it's turned off, but still plugged into the mains, electricity is not flowing through the elements. If it was, they'd still be glowing.

However, poking anything inside may touch something that is live - there are still metal parts inside which are connected - and it may be inadvertently 'switched on' as it would if there was something being toasted.

So, the sensible thing to do is keep anything electrically conductive out of the slots. A wooden or plastic implement works to remove stuck toast, but why leave the thing plugged in? Of course, if you stand on a rubber mat on a wooden floor the electricity isn't going to flow through you to earth, but if you hold the toaster with the other hand... there are other ways to commit suicide.

Bottom line - when plugged in, there is potential danger, and there's no point trying to disprove that.

I have actually stuck a knife into a toaster, and I can confirm that yes, it is very definitely electrified. Please, Please, Please, don't do this. The only reason I'm still alive is because of a good fusebox / safety switch and the fact that my hand spasmed in such a way that I let go of the knife.

The toaster is going to have heating elements of a type of wire that has very high resistance, usually nichrome wire. When electricity is applied to the wire, it becomes hot enough to toast bread.

You'll notice if you look closely that the wire is supported by some form of non-conducting brackets, sometimes ceramic. This prevents the wire from following a shorter path than desired, reducing the resistance of the circuit.

If you force a foreign object into the slots and dislodge the nichrome wire from the brackets, and it contacts a conductive portion of the toaster and your body is in contact with that portion and your body also has a clear path to ground, it will no longer toast the bread as desired.

If the circuit to which the toaster is connected is protected by a GFCI device, you may survive the experience.

After the toast is toasted, the circuit will turn off, removing electricity from the nichrome wire, reducing the danger. One may still be able to contact the switching circuitry that provides the electricity, but it's more difficult.

In earlier days, people were perhaps more aware of the dangers and able to educate the family members. For those who were unable to understand, think of it as evolution in action.