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.