A while ago I made a video on the US electrical system. It was a basic overview designed principally
to get those of you in 240 lands to shu— uh, to understand that we are also a 240 land, but since we use split-phase power most of our circuits operate at half that voltage and the full 240V potential is generally limited to high-power devices on dedicated circuits. Using split-phase power has some real advantages particularly when it comes to safety - and on that note at the end I’m gonna add some clarifying words there because in the time since that video I’ve discovered an interesting language quirk regarding that discussion. But anyway this video isn’t gonna defend our electrical system. In fact, it’s about perhaps the worst part of it! And no, it’s not just our terrible, fully-metal plug design or completely unshielded receptacles. Although for what it’s worth, tamper-resistant receptacles are now available and usually required in new-construction. But anyway, this problem has actually nothing to do with a building’s wiring or the receptacles or plugs. Instead, it’s that these exist. And these. And especially these. Now there’s nothing wrong with extension cords or power strips themselves, it’s just how they’re implemented which is the issue. Here’s a silly fact to preview the problem at hand: A strand of Christmas lights is a safer extension cord than most extension cords. Yeah. I’ll explain why in a bit, but first we need to address a common misconception. Circuit breakers! What are they for? Well, you might think that they’re there to protect you and your stuff. This belief is pretty understandable, after all one of the most common ways they get tripped is when one of your electrical stuffs has a bad time. And since they cut the power to a given circuit when they do their thing, well it stands to reason that they also help prevent electric shock. But a breaker like these does no such thing. It couldn’t care less about your stuff, and quite frankly it doesn’t care about you either. Of course, there is some nuance here with
the advent of arc-fault circuit interrupters, and while we usually only put shock protection
devices at the receptacle in locations where hands can be wet, breakers with integrated residual current devices (although we call them ground-fault circuit interrupters) are available. I actually made a video about that tech if you want to check it out. It’s pretty interesting. But anyway, since AFCI breakers have only somewhat recently been mandated by code and GFCI breakers are, frankly, quite rare here you’re going to find lots of electrical panels like this one, filled with nothing but bog-standard breakers. And these have one job and one job only. To protect the conductors in your walls. That’s it. They frankly do not care what happens when the electricity leaves the wall, they just want to know that you’re not overloading the wiring coming out of them. They will stand idly by as you get zapped
or as your television has a meltdown, and will only intervene once the current going
through them exceeds their rating. Circuit breakers like these are overcurrent
protection devices for a structure’s electrical system and nothing more. They reduce the risk of electrical fires occurring
due to an overheating conductor igniting a wall stud or whatever, but that’s about the only thing they can do. Now, that is very important! A given conductor (so, a wire) can only carry so much current before its own electrical resistance becomes significant and it begins to heat up. And that’s…. Bad. Imagine you had a coffee maker and a microwave and, why not, also a toaster all connected to the same circuit. This can be easier to accomplish than you
might think, as many adjacent outlets are simply daisy-chained and share the same wires in the walls (though in fairness, kitchens are usually designed more smartly to avoid this). Now, on a 15 amp 120V circuit, 1,875 watts is the maximum that can be safely drawn. And in fact, that number is really only good for non-continuous loads. Devices which draw a load continuously are limited to 80% of a circuit’s capacity. Let’s say the toaster uses 750 watts. And we’ll imagine the coffee maker is 1,000. Making some toast while brewing coffee is really close to the limit, and if you decide to microwave some bacon while that’s going
on… now you could easily be more than a kilowatt over. That is going to cause the wiring coming from
the breaker panel up to wherever you are to get pretty hot, particularly where splices and other connections have been made. Because there tends to be flammable material in or near walls, this is very bad. And that’s why these are here. They help prevent that. If you pull more power than the wires can
safely carry, the breaker will trip and kill the circuit. How do circuit breakers work? Well, we’ll save that for later. And then we’ll get into the stuff like arc-fault protection and other goodies. I’ll try to remember to come back here and
put a card for that video but I have a bad track record, there. Anyway... Here’s the problem. This will do a fantastic job of making sure
the wiring in your walls doesn’t get overloaded. But once you’re outside of the wall, this won’t help you. And since we like to cut costs wherever possible so we can sell cheap stuff, you will find countless extension cords and power strips which cannot safely handle the capacity of the circuits they’re plugged into. Let’s talk about wire gauge. The amount of current a given conductor can
carry safely depends on what it's made from as well as its total cross-sectional area. And also length. There’s some nuance with stranded vs. solid wire and with really weird stuff like the skin effect but we’re not going there. Now, I’m going to be talking in the American Wire Gauge. I know, not everyone uses that. Here’s a chart for those that want it. But the main point is that a given gauge of
wire has a given maximum current it can carry before it becomes a problem. Now, crash course. The smaller the number, the thicker the wire. 14 gauge wire can carry less current than 12 gauge wire. 12 gauge is thicker than 14 gauge which is
thicker than 16 gauge and so on. It’s confusing, but are you really surprised? Except for circuits which handle things like
water heaters, dryers, stoves, etc, you’re generally going to have a mix of 15A and 20A
circuits in an American home. It has become pretty common these days to
run 20A circuits for most receptacles and reserve 15A for lighting circuits. But not always. Now it shouldn’t surprise you that 20A circuits
need thicker wires than 15A circuits. In runs with typical lengths, 15A circuits
will use 14 gauge wire. And 20A circuits use 12 gauge wire. This is what that wiring looks like in homes all across the country, with some particular caveats. We don’t need to get into that. Discuss in the comments. It boosts engagement. [THERE'S AN ERROR HERE - SEE PINNED COMMENT]
Anyway, this is called THHN wiring, short for Thermoplastic High Heat-resistant Nylon-coated (cheaters) wire but often it’s just called Romex, which is to household wiring as Kleenex is to facial tissue. Conveniently, it’s been color-coded for many years now. 14 gauge wiring has white sheathing, and 12 gauge wiring has yellow sheathing. It helps you know at a glance which is which, and yellow wires will be for 20A circuits, white wires for 15. Oddly, there is also orange for 10 gauge wire, good for up to 30A depending on the length of the run, but then after that color coding
goes out the window. ["I dunno" noise] Anyway, the circuit breakers? They’re protecting this stuff. They’re making sure you don’t put too
much current through these wires. But these wires are inside your walls. This one goes on the outside. And the problem is that this cannot handle
the amount of current that the wires in the walls can, especially on 20A circuits. But your circuit breakers don't know that. Now this doesn’t have to be a problem. One of the best features of the UK’s electrical
system is that the plugs have fuses in them. Now, the reason for that is kinda weird. Ring circuits. What were you thinking? But anyway the lasting benefit there is that
you could provide overcurrent protection on the other side of the wall, allowing you to safely use smaller wiring that’s sized according to the device’s needs. If you put in a 7A fuse, well then that fuse will blow before the wire gets overloaded. Simple. Trouble is? We don’t do that over here. This extension cord has 16 gauge wire in it, and it’s only rated for 1,625 watts, or 13 amps. And yet, it has nothing to stop you from exceeding that. Isn’t that lovely? Even a 12 amp load, which is technically OK to put on this, makes the cord disconcertingly warm. But on any otherwise unloaded circuit, you can still pull at least another three amps through here without the breaker tripping. As far as it's concerned, well there’s nothing wrong. 15 amps are on the wires in the walls, which is OK. But it’s not OK here. Keep a wire overloaded for too long and it will get very hot. And since flammable stuff may be around it, well that can easily start a fire. In fact, the wire’s insulation itself is often flammable, so if you let it get hot enough it will just spontaneously combust. Fun! Oh, and even relatively slight overloads can be a problem. If you have a long cord coiled up like this, the wire at the center of the bundle will get very warm thanks to the lack of airflow (and the fact that it’s surrounded by other warm bits of wire). This is a fire hazard that we’ve just decided is… fine, I guess. And it’s not limited to these cheap cords. Go to a hardware store and you’ll find plenty of “heavy-duty” looking cords that are in fact only 16 gauge. They cannot safely supply the entire amount
that the wiring in the walls can, which means it can be overloaded without your circuit
breakers intervening. And this is just… normal here. You’re just expected to know that this cord
is only rated for 13 amps, and that if you really need 15 amps you gotta pony up for the 14 gauge cord. It’s frankly bonkers. Oh, but it’s actually worse now that 20A circuits are so prevalent. Don’t get me wrong, 20A circuits are largely a great thing. They allow for much greater flexibility in individual rooms, especially in the kitchen where nearly everything is a high-power device. But consider something like this power strip. This actually does use 14 gauge wiring and could be used safely on a 15 amp circuit. Its limit and the circuit’s limit are the same, so if you’re overloading this thing you’re also overloading the circuit so the breaker will intervene. That’s ideally how everything should work. But on a 20A circuit you can now severely
overload this without the circuit breaker caring. And of course that problem still applies to
a cord like this which can handle even less. The outlets in this room are on a 20A circuit. So I could plug a space heater into this. And also another one on medium. That is now 20 amps going through a cord which is only rated for 13. It’s a very dangerous situation, especially if the cord is near anything flammable like, oh I dunno, curtains. Carpet. A sofa. Stuff that goes in houses. And yet we’re not overloading the circuit
so as far as this guy is concerned it’s A-OK. Complicating things further is that you don’t necessarily even know what circuits are 20 amps and which ones aren’t. This is a NEMA 5-15 receptacle. It’s the normal one you find everywhere here. And this is a NEMA 5-20R receptacle. You will only find these on 20A circuits. The neutral pin is T-shaped to accommodate a NEMA 5-20 plug which looks like this. You basically never see this plug outside
of commercial settings as it’s reserved for devices which actually need more than
15A to operate. But, you aren’t always required to use NEMA
5-20R receptacles on 20 amp circuits. In fact, if I’m reading things right, you almost never have to. You can just use NEMA 5-15 so long as there’s
more than 1 individual plug on a circuit. Which, because duplex receptacles are the
norm here, there pretty much always is. So anyway, you usually can’t tell by looking
at an outlet if it’s a 15 or 20A circuit, and we don’t put protection on things like
extension cords so really it’s just a mess. It’s terrible. It is way too easy to create a dangerous situation
with a power strip or extension cord. So, how do we manage with this terribleness? Fear. If there’s one aspect of electrical safety
that has successfully permeated through American culture, it’s that plugging things into other things is dangerous. It’s practically a trope at this point. And frankly, this is almost too effective. When I revealed the details of this set I showed the cabinet of power strips that everything’s plugged into and y’all freaked out! Now I’ve put this set on a power meter,
and the entire thing uses 256 watts, barely more than 2 amps. The whole thing could easily be run through
a cheap extension cord like this. This is not actually dangerous. But lots of people see this and cringe, which frankly is great. If we can’t do things right on the infrastructure side, we can at least make people leery of doing stuff like this. And the National Electrical Code has some
rules as far as how you need to build-out an electrical system. If you’ve ever been in a reasonably modern American home, you’ll probably have noticed that there are outlets. Everywhere. The purpose of this is to minimize the need
for extension cords in the first place. Because the folks at the NEC recognize that these are bad. See, the theory is if there’s an outlet within six feet of any point on a wall well you shouldn’t need an extension cord since 6
feet is more or less the standard length of a power cord. But guys. I gotta ask. Have you considered, maybe, making extension
cords less bad? This place follows those outlet-spacing guidelines but I still use extension cords. In fact the main reason I use them is because, well,
they have three plugs on the end. It’s nice to be able to plug in a lamp,
phone charger, and another thing while leaving the other outlet free for a laptop or a vacuum
cleaner or whatever. These aren’t going away, is the point. They’re just too convenient. Really, we should have been copying the Brits this entire time. I mean, honestly, it can't be that difficult to design
a plug that contains a fuse. In fact, we’ve already done that! These weedy little plugs in our Christmas lights contain fuses. Christmas lights are cost-cut to a ridiculous degree and have something absurd like 22 gauge wiring going through them so there needs to be a fuse since you can only safely pull, like, I dunno, 3 amps through here. That’s why I said Christmas lights are a
safer extension cord than most extension cords. They actually have overcurrent protection. Granted, they don’t work so well as extension
cords since they’re usually not polarized but hey. The point remains. Frankly, if we’re gonna keep selling extension cords like this that can’t even carry the minimum current of our smallest circuits, maybe we oughta put fuses in them. Ideally it would go here so it protects the length of the wire, but I’ll settle for putting it in the other end if it makes things easier. Sure, if suddenly we were like “extension cords need fuses now!” that would be confusing (heh) and annoying to a lot of folks, but it would be a heckuva lot safer. And fuses are very, very cheap. It wouldn’t add much cost to the cord set, and if people are using them correctly they’re unlikely to blow in the first place. And for what it’s worth, power strips aren’t
always terrible. Lots of them - but certainly not all, to be clear - actually incorporate circuit breakers of their own. Ever notice that the switch says “reset” opposite of "off"? That’s because this toggle is actually a small circuit breaker and not just a simple switch. Look. I plug two space heaters into this and it trips. Now, lots of people will say “never plug a space heater into a power strip” and honestly that’s not terrible advice. A lot of these are made quite cheaply and they do get… kinda melty sometimes. But the effort is at least often made. Now here’s where I step back and ask, how bad is this really? How many house fires are started due to an
overloaded cord or power strip? In fact, I don’t think we know! It looks like it might not be that many. According to a 2019 report by the National Fire Protection Association, only about 10% of fires can be blamed on electrical distribution
and lighting equipment, of which only 11% can be blamed on cords or plugs, and further of that subset only 12% could be blamed on overloaded equipment. So, we’re talking 12% of 11% of 10%. Or about a tenth of a percent of all fires. However, I personally take issue with this particular study because “electrical failure and malfunction” is really, really, vague. And that category gets a huge proportion of
all the known fires which makes me think it may not mean a whole lot. Now, I don’t know anything about fire investigation
so don’t take my word for this. But I do have to say that I feel this category
is being used as a catch-all and I don’t know what exactly it can tell us. The report even says 50% of these fires are
of unclassified cause so, frankly, I don’t know how useful this study is for this particular
discussion. And in fairness, I get it. Investigating the cause of a fire is tricky
when everything was on fire at one point. This whole “electrical failure, malfunction”
category also finds its way into this FEMA study where it accounts for 88% of electrical fires! ...what? Again. I’m gonna stress that I am a person on the internet with a Google. This is speculation and conjecture, nothing more. But this study also says that in almost 31%
of electrical fires, electrical wire or cable insulation was the first thing ignited. Annoyingly, though, that could mean cable in the walls, or lamp cords. Who knows. However we do see up here that only 8.7% of
electrical fires start in a wall cavity or concealed space, which, if my grasp of math is at all intact, means the majority of cable and wire-related fires occur outside the wall. Which frankly makes sense because that’s
beyond what a circuit breaker is designed to manage. The only conclusion I feel comfortable making
here is that I don’t have enough information to come to a meaningful conclusion. I don’t think this isn’t a problem, especially since 20A circuits are so common these days, but in all likelihood it’s probably still a small one. People are well-trained to be leery of overloading stuff, for the most part. As it is, electrical problems are by no means
the leading cause of house fires, accounting for only 13% in the US. But I do think it’s telling that the NEC
is making us put outlets everywhere so that we don’t need to - or shouldn’t need to - use
extension cords. It seems we know that they’re dangerous but are addressing that danger in what I would call an insufficient way. I understand the impulse to eliminate the need for extension cords which would in theory nip the problem in the bud. But as I said, extension cords are often used
not because there’s no outlet within reach, but because it’s a cheap and convenient
splitter. I think the problem at hand is imagined incorrectly, so the solution doesn’t fit. I would say we should consider addressing
the danger of the thing itself, and not try to reduce the need for the thing. We could mitigate much of the danger quite
easily with a ten cent fuse in the plug. Our electrical safety isn’t exactly… great. I don’t think it’s awful by any means and it does continue to get better year over year, but we could do with an examination of all these items. If you’re smart about how you use extension
cords, you really don’t need to worry. But it still makes me uncomfortable how we’re
OK with stepping the wire gauge down twice once it leaves the wall and not doing anything
to prevent overloading it. And frankly, this isn’t even limited to extension cords. As far as I’m concerned everything should be protected by a user-replaceable fuse sized for its cord set and purpose. You know. Reasonable precaution. What a concept! Anyway, for now, just be smart with extension cords and power strips. Be sure to use one that’s appropriate for
whatever you need to do with it. And to be clear, I use these cheap ones all the time, it’s not like I have anything against them or consider them terrifyingly dangerous It’s just… there’s a component of risk to their use that I feel should be more widely known and, hopefully one day, addressed. To close out, here’s that language quirk
I mentioned in the beginning. It has to do with the word “safer.” See, here’s what I said in that original video. In any given scenario where one is receiving
an electric shock, a lower voltage is safer than a higher one when all other factors are the same. Therefore, 120V could (and I would say should) be considered safer than 240V. Now, here’s where things get wonky. I use the word “safer” synonymously with “less dangerous.” Just as how I think extension cords would
be safer if they had fuses. But that doesn’t necessarily mean that they
would be 100% safe. But I found that a lot of people interpret the word “safer” as implying some amount of baseline safety. I found out because people told me! And the thing is, that’s just not at all how that word functions for me! I use it literally as a stand-in for “less dangerous.” Or perhaps "less risky." Like how driving 100 miles an hour with your
headlights on is safer than driving the same speed in the dark. That statement doesn’t suggest to me that
driving 100 miles an hour is a safe activity. It’s just safer than doing 100 by moonlight. To me “safer” is always a comparator alone, and
doesn’t bring its own implication of any safety. So… yeah. I actually was genuinely delighted to hear
this explanation because I was starting to lose my mind thinking Ohm’s law was a trick or something. And I am absolutely in agreement that the shock-mitigation efforts in 240V countries are by and large much better than ours. It’s stupidly easy to get a shock here. Seriously. Just hold a plug wrong and you’ll get a tingle. So I’m not saying that our electrical system is safer than your electrical system. Because it’s undeniably not. But I am saying that, because the voltage is lower, electric shocks are less likely to be fatal over here. And that’s why our efforts to prevent them
are half-assed. The voltage itself is safer, as in less dangerous. The electrical system as a whole though sure isn’t. Anyway, toodles! ♫ overloadedly smooth jazz ♫ It couldn’t care less about you and your.. Shoot! Circuit breakers like these are over-
[thud] Well, that wasn’t nice. ...igniting a wall stud or whatever, but that’s a … blpppt. Would you please stop doing that? This is a NEMA 5-20R receptacle, and I’m holding it upside down. You can tell that I start every shoot with everything I need. Right? I don’t think it’s awful by any means, and it does continue to de get de be de de de de bu debba du And especially… these. And I only got the one. Oh well. Hi. It's the end. As in, the part where the video stops. Now you can watch something else. Maybe click on the little (i) doohickey and see the other videos of mine that I referenced? Just a suggestion.
Back in 2006, George W. Bush said, "America is safer than it has been, yet it is not yet safe." I remember people saying this statement was nonsensical, as if they couldn't understand that something can move toward the "safe" end of the safe/unsafe spectrum but still be in the "unsafe" half.
(Note: this comment is not an endorsement of Bush's foreign policy.)
So I decided to take a look at the cheapo extension cord I bought recently. It was exactly the same as the example in the video, max 13 amps. But I live in a 240 country, so almost all of the breakers in this apartment are also 13 amps, while still allowing more power than the 20 amp breakers mentioned in the video :)
Incidentally, there's also a 400 volt 15 amp 3 phase breaker for the stove/oven combo.
Not an electrician, but would it be possible to have some sort of fuse adapter at the outlet to accommodate for the 16 gauge extension cords?
In your blooper reel, you say that you’re holding that receptacle upside-down. You were actually holding it the right way up! By design, the ground pin is supposed to be on top, so that if something falls onto a plug that’s partially out of the socket, it’ll bounce off the ground lug rather than shorting across hot and neutral. That said, with the exception of hospitals, just about everybody installs receptacles with the ground pin on the bottom - since it looks more natural that way, maybe? Tradition? Who knows.
So when I was overseas in a country that uses 220V (that doesnt use the plugs with fuses) and similar plug layout as the US (two straight flat parallel prongs) , I found a passthrough looking adaptor for a plug that had a on/off switch and it looked to have a fuse inside.
Any experts know about such a thing?
Im gonna have to look for those again now I have more delicate and expensive equipment for my travels if they actually help.
Some videos mentioned directly or transitively:
(I think it's much more convenient to add these links in the video description too. Then they're always there and I don't have to start the video again and look for the i at upper right.)
The location of a fuse or breaker within an extension cord can't make a difference, at least for the normal layout with all of the receptacles on the end. Unless there's receptacles half way down the cord, the current will be the same throughout the cable, so fuses and breakers will work equally well on the receptacle end as they will on the plug end.
Also, for a given current limit, ring circuits in and of themselves are safer, because they put less current through the wires. What's unsafe is using 30 or 32 A current limits on that ring.
From personal observation, I've seen most electrical injuries are from DIY work gone wrong, and having 7.68 KW potentially available at every outlet or stretch of wiring is a bit disconcerting. The drill bit that just made contact with your household wiring isn't going to be fused. (Although I have heard stories of them vaporizing on contact.) I'll take 1.8 or 2.4 KW max, even if it means my kettle takes longer to heat up. I don't think any flaw in the US system is as large of an issue as that.
Technology "It boosts engagement" Connections
One thing about the required spacing of electrical outlets, I've always heard one of the reasons for their requirements (particularly requiring one in walls over a minimum length) has to do with limiting tripping hazards to people walking.
In my 1920s house there's about 1 original outlet location per room. If you needed power all around the room from a single point like that then that's a lot of trip cords lying around the room
edit: 1920s house*, I'm sure by the 19020s houses will be built a lot better ......or maybe knob and tube will have a comeback then too as some sort of appreciation for a simpler time.