Switches are Clicky; Here’s Why

Don’t ya love it when you’re learning
about something and things, just, click?
Like a light switch!
Clicky switches are pretty fun.
But why do switches make noise?
What’s the point of all that clacking?
Well, it has to do with the fact that you’ve
been lied to.
Uhh, but let’s not get too conspiratorial
just yet, first let’s look at some of the
switches that don’t click because there
are some.
This electronically controlled dimming module
turns the lights on completely silently.
No clicking there.
Then again, this other one that’s not a
dimmer makes a pronounced clicking sound.
[pronounced clicking sound ]
And I didn’t even touch it!
What gives?
Well, the dimming module is using a solid-state
device known as a triac to actually turn the
lights on and off, so it’s not quite what
I mean by a switch.
This standard thing goes on or off module
does in fact use a type of real switch to
do its work, so you hear a click.
Same with this toggle light switch.
This rocker switch.
This rotary switch.
This lamp cord switch.
This power button.
[softer, double click]
The rocker switches
on this studio light.
[four clicks in a row]
Oh, and the big one,
[a somewhat softer click]
This toaster.
[a click that’s Automatic Beyond Belief]
The mode selector on this space heater.
[clicking as it turns]
Even its thermostat
makes a distinct click.
[soft, repetitive click]
But why?
Why be so clicky clacky all the time?
To start to answer this question, we first
need to answer a simpler question;
what is a switch?
Well, a switch is a handheld game –
A switch is a mechanism used to divert rail
cars fr –
A switch is the simplest mechanism that can
control the flow of electricity.
[pleasant chime]
Say you have a simple table
lamp and want to connect it up with the power grid.
Well, we simply take its bare wires and carefully
touch them to these live wires and voila!
Let there be light.
Now to turn the light off, all we need to
do is carefully pull those wires apart, and
hope the live ones don’t t–
[electric arc
and explosion]
But this is pretty dangerous.
Even Edison knew that.
So we designed electrical sockets which contained
live wires behind an insulating barrier and
we designed plugs that would, depending on
your country, somewhere between somewhat safely
and completely safely allow you to make and
break electrical connections.
But this isn’t the most convenient way to
turn something on or off.
And most importantly, using them that way
isn’t good for your plug or your receptacle.
See, if I take this lamps and plug it into this outlet, it lights up no problem!
And if I simply unplug it, it goes out, also
without a problem.
But watch what happens if I take this space
heater and unplug it while it’s running.
Ooh, that was quite a spark!
Let’s do it again!
Let’s do it again.
Big one!
Let’s do that again!
Let’s do… let’s do that again!
[VOICEOVER]: While this specimen continues
to be amused by the sparks,
we’ll move on to the next jump cut.
When the heater is running, a lot of electricity
is flowing into it through this cord.
1,500 watts, in fact.
To stop that flow of current, all we need
to do is put an insulator between the contacts
of the receptacle and the pins of the
Which of course we can do simply by unplugging
But when we unplug it, it doesn’t just stop
the current flow right away.
There’s a brief moment where that current
manages to jump out from the outlet, and the
result is a spark.
The same thing happens if you plug in the
heater with it turned on, right before the
pins of the plug and the receptacle first
make contact, but the spark usually isn’t
as large as when an active connection is broken.
And this is where you’ve been lied to.
See, when you were little, you were probably
taught about electrical conductors, like the
wires in this cord, and electrical insulators,
like the plastic insulation surrounding that wire.
If you had a really nerdy teacher you might
have learned about semiconductors, but lots
of us were sorting things into the two categories
of insulators and conductors.
The lie is that, just like most things in
the real world, the electrical conductivity
of any given substance exists on a spectrum.
Everything conducts electricity when you try
hard enough.
Even air.
Now we rely on the resistance of air all the
Electrical transmission lines are typically bare aluminum
and are held up in the air by stacks of insulating discs.
The higher the voltage of the line the more
of these discs you need because even they
aren’t perfect insulators.
Nothing’s a perfect insulator!
And that’s the problem.
Air’s pretty good, and when you unplug something
from an electrical outlet you do disconnect
it from the power grid and stop the flow of
electricity to it precisely because there’s
air now between the pins of the plug and the
conductors in the receptacle.
But, when you pull that plug out of the wall,
there will be a brief moment when there’s
only a tiny bit of air between the plug and
the socket, and this is not good.
When those contacts are close but not quite
touching, the air gap is so small that the
breakdown voltage, that’s the voltage at
which an insulator fails to stay an insulator,
is lower than the voltage of the electrical
This means that the current will actually
jump the gap, and this creates an arc discharge.
That’s the spark you see here.
Now on its own this isn’t particularly bad.
Thanks to the fact that we use AC power, the
voltage crosses the zero point 100 or 120
times per second, so that arc will usually
go out nearly immediately, though it should
be noted that arcs can be sustained on AC
More importantly, the breakdown voltage of
any insulator, including air, is a function
of how thick it is, so once the contacts are
just a millimeter apart, that arc will generally
be unsustainable.
But here’s the problem.
That arc is hot.
Very, very hot.
So hot, in fact, that it can burn the ends
of the plug and the socket.
So we don’t want to rely on pulling the
plug out of the socket to stop current flow.
What do we do instead?
We use a switch.
All the switch does is create a break in a
There are many different types of switches
but they all do fundamentally the same thing.
There are two electrical contacts, and they’re
either touching, or they’re not.
If they touch, current can flow.
And if they don’t touch, current can’t.
But then, switches do the same thing as unplugging
Don’t they have to worry about arcing?
Yes, in fact even more so.
Electrical arcs damage electrical contacts
in various ways, but among the most significant
ones is that the contacts eventually… melt
See, each time there’s an arc, that plasma
is so hot that the surface of the contact
briefly melts, and that material can sputter
off of it.
Additionally, the high temperature can cause
corrosion of the contacts, and you get lovely
issues like carbon buildup which increases
the electrical resistance of the contacts,
and that’s not good.
Even better, if the arcing is bad enough,
and the surface of the contacts get hot enough,
they can weld together and get stuck closed!
I guess that light’s on forever now…
Since the contacts in a switch are generally
pretty small, we want to minimize the arcing
that can happen because, well, an arc will
warm them up quickly and cause all those problems
I was just going on about.
And how do we do that?
Why, with speed!
Remember that household voltages are low enough
that an arc generally can’t be sustained
once the contacts are just a millimeter apart.
So, if you get them apart quite quickly, any
arc formation that does occur will be very
brief and unlikely to cause significant damage.
And that is why switches click.
Switches are designed with mechanisms
to ensure the contacts open and close very quickly,
quickly enough to prevent an arc
from lasting more than maybe a millisecond or so.
Effectively the contacts are meant to slam
together and then get yanked apart, and that
makes an audible click.
The mechanisms that accomplish this are often
ingeniously simple.
Many times it’s just a spring cleverly integrated
into a pivot.
Let’s take a look at a simple household
rocker switch.
This switch is nice and clicky.
[repetitive, rapid clicking]
Who needs a fidget clicker
when you can just run to the hardware store
and get one of these?
This design is almost devilishly simple.
Below the faceplate are three pieces of brass,
two of which are the same ones you attach
wires to on the outside.
The smaller one holds an electrical contact,
and the larger one serves as a pivot point
for a small swinging piece that holds the
other contact.
If there’s a torque applied to the swinging
piece in this direction, the contact does
not touch the other one, and no current can
flow through the switch.
But, apply a torque in the other direction,
and now the contacts touch.
Current flows into the switch through this
terminal, through the basket thing,
into the swinging thing, through the two contacts,
and out the other terminal.
All it takes to ensure the swinging contact
moves quickly is a spring.
See, the rocker paddle that you touch is in
fact the same thing moving the contact.
These grooves hold onto the edge with a little
play, and when the rocker rocks back and forth,
so does the contact below.
But thanks to the spring, the rocker (and
more importantly the contact) wants to stay
in either position.
The spring gets increasingly compressed as
the rocker meets the apex, and once it passes it…
bam, the spring expands and pushes the
contact it in the other direction.
The result is a swift action in both directions,
minimizing arcing.
Pretty clever.
Unfortunately, though, this switch design
isn’t perfect.
In fact, many (if not most) switches on sale
today aren’t.
See, you can actually move the contact a bit
before the spring takes over.
If you carefully apply pressure on the switch,
you’ll see that the light goes out before
it clicks into the off position.
Listen carefully and you can actually hear
arcing going on inside the switch.
[faint arcing sound]
This… isn’t really
great, especially if you have a lot of lights
on the circuit you’re controlling.
In fact you can see on these contacts that
they have been slightly damaged, and this
isn’t a very old switch.
I know because I installed it myself.
Granted, most people don’t turn the lights
on and off like this.
If you do it like a normal person, then the
contacts are swiftly moved and arcing is minimal.
Still, it annoys me that it’s even possible
to damage the switch at all.
Many switch designs, like these lamp cord
switches, are simply impossible to hold in
a half-on, half-off state.
Sure, they’re not designed to carry the
current of a normal light switch, but I bet
these guys rarely ever fail from bad contacts.
And normal switches can be made impossible
to abuse.
The house I grew up in was quite old, and
a few rooms had toggle light switches that
you could actually move nearly completely
into the opposite position before the internal
mechanism opened or closed the contacts with
a very loud clack.
[a very loud clack]
Those switches were in
service for 50 or 60 years and likely still are.
Granted, they were only controlling a single
light in all but one case (if memory serves)
so they weren’t ever under much electrical
stress, and they required much more force
to use than modern switches, which is probably
why that style went out of favor.
But, this paddle-style dimmer switch has a
mechanism that prevents partial making and
breaking of the contacts without requiring
significant force.
You can see that even if I use my two thumbs
on both sides of the switch and very, very
slowly move the paddle, the lights only go
on and off with the click of the internal
This design here is what I’d call ideal,
and it proves that easy-to-use switches can
still be made with a fast, clicky, abuse-proof
So if you’re shopping for a light switch
at a hardware store, tactile feel of the switch
does actually matter when it comes to switch
A nice, solid snap makes me more confident
than a smooth, quiet movement.
This cheap toggle switch is what I’d consider
The toggle moves smoothly without much resistance
at all, and the contact is actually broken
when the switch has barely moved out of its
resting position.
It actually requires conscious effort to ensure
the contacts are quickly moved apart, and
I doubt this switch would last more than a
decade on a circuit with more than a few lights.
In fact, it’s not even fair to say that
this switch actually clicks.
It more or less thuds.
Any switch that’s designed to interrupt
even a modest current flow should, in my opinion,
have a nice audible click.
That plug-in thing-goes-on module?
It got a relay in it.
Relays are electromechanical devices that
control large currents with small currents.
Essentially they’re a switch with some sort
of external control.
In this case, the small computer inside here
will turn on the relay when it’s been asked
to, and click, the light goes on.
The contacts in a relay are closed via an
electromagnet, and are held open with a spring.
And, as luck would have it, this simple arrangement
means the switch opens and closes quickly.
And so, it clicks.
Fun fact!
When we need to automatically control very
high current loads, we use what are essentially
large relays, but we call them contactors.
Contactors often just use air to break the
circuit like any other switch, but when we
get into high voltage applications, the contactor
might be contained in a vacuum, and in really
high voltage applications like in power grid
substations, you might find switches and circuit
breakers inside a volume of sulfur hexafluoride,
which is an incredibly good insulator and
this is in fact the primary commercial use
of SF6.
Now, not all switches need to click.
Switches that don’t carry a lot of current,
like the clicky buttons on your mouse, don’t
need to click at all because there’s not
gonna be any arcing going on in there.
They click mainly because that style of switch
is designed to provide a lot of tactile feedback.
And actually, a very clicky switch can be
a disadvantage in digital devices, because
now you might need to implement some sort
of debouncing but that’s beyond the scope
of this video.
Now you know why switches click.
They’re really just prolonging their life.
And if you want to prolong the life of the
switches in your life even more, be sure you
always give them a good flick.
Or, poke.
Since many modern designs kinda make you a
part of the contact closing and opening action,
you can and should click to your heart’s
Thanks for watching!
And thank you to the fine folks supporting
this channel through Patreon.
I really do appreciate your support.
If you’re interested in joining these people
in supporting the channel, you can check
out the link at the end screen, or in the
Thanks for your consideration, and I’ll
see you next time!
♫ illuminatingly smooth jazz ♫
I messed up.
I thought this would go quickly, it’s not
going quickly.
So, if you get them apart quickly …
That was going well, but then it wasn’t.
Wrong pronunciation!
[struggling sounds]
No no no, that’s the wrong way!
[more struggling sounds]
[also the tripod is creaking, that’s fun]
Now, no I don’t like how I did that eith… eugh.
eugh, well, ugh.
Cra.. that might have been, erm, nevermind.

100 thoughts on “Switches are Clicky; Here’s Why”

  1. Does that mean it's not good to try and make the switch silent by very slowly moving the switch from off to on or vice versa?

  2. Well, looks like I'm going to have to go switch by switch through my house and then make a trip to the hardware store…

  3. Surprised you didn't mention how because of switches like that, the word "click" became a prominent word in our vocabulary … but I clicked the like button anyway. 😀

  4. The compontents wearing out thing does annoy me as well. Just like when thr blades in a newer wall outlet is so worn the plugs start to fall out 😬. Same with USB ports etc

  5. If you flip a switch in the woods and nobody is nearby, can anyone hear when a bear shits on the pope. Or something to that effect. Drinks on the house.

  6. Reminds me of the 36kV switchgear at work. Have to put on a whole suit to remove the breaker from the bus due to dangers from arcing.

  7. Really disappointed at the lack of switch-related sex jokes in the comments

    what is this, a family friendly education channel???

  8. RIP to all the people who heard this: "We simply take its bare wires and carefully touch them…" and never got past that part

  9. There was a time in the 1990's that companies made "silent" switches. Yet industry realized consumers preffered a noisy switch. So the silent switches were phased out.

  10. 10:31 Oh my, you suddenly remind me of some of the light switches in my paternal grandparents' house, before they had it rewired sometime in the 1990s… They also had 1940s/50s-era hardwired black Bakelite pulse-dial rotary phones on most of their extensions until 1995, and damn I wish I could've been there to get in the way and collect those old phones… =(

  11. Here's a question for you: Why is the… um… "*pirk*" sound of the "classic" North American light switch so hard to record??

  12. What about those switches in the public shitters that you just push in and they come out at the same time your shit is and you have to get up of your arse and push them again?

  13. Then there is me and my misophonia that would rather replace a switch every few years than deal with the click.

    Often wondered why nobody had made a completely silent switch, but now I know.

  14. There have been residential switches that were silent, or at least were marketed as such. These switches were mechanical in there design and I believe were made by General Electric. There were of course mercury switches made as well.

    One thing for sure, always pay close attention to the voltage and current rating for the TYPE of power you are going to switch on or off! DC is a very different "animal" in the way it behaves, especially when switching inductive loads. This is why DC ratings are always lower than AC even on the same switch device, as much as 50% lower. The reason is, DC can sustain a rather large/long arc.

  15. 2:12 🇬🇧Rule Britannia; Britannia Rules the (50Hz) Waves; Britons Never Never Never Will Be Slaves (to non inferior plugs)

  16. Alex, you might care to do a follow up video on some of the other things that many "contactors" do to break the arc upon opening. In addition to separating the contacts quickly, they need to discourage the arc by inserting a barrier; this may be done by a mechanism sliding a wafer or wedge insulator between the contacts as they open, or on some the moving contact sort of flips around the corner of a stationary insulator. Electrical arcs don't like to go around corners, so even a small deviation from a straight path between contacts can extinguish an arc…..this is the same reason that insulators on high tension power grid wiring are formed as a series of disks….the arc can't follow the curvature around the disk edge.

    Another subtle thing often done on switch contacts; a wiping action that not only slams the contacts together, but also causes them to have a slight sliding motion as they come together. On higher power contacts, this can help reduce the formation of points on the contact surface that will reduce the insulation voltage of the switch. On low power contacts, this wiping action keeps the contacts clean and free of corrosion.

  17. Erosion from electrical arcs is a technique for machine metal. It’s called EDM (electro magnetic discharge) and it uses spark erosion to cut conductive metals.

  18. For me, the sound that the switches make is really satisfying, and I hate it when they don't click, because I need some kind of audible feedback to know that something's working.

  19. No mention of the arc ionizing the air and creating a conductive path? That's why the spark is more impressive when disconnecting. The arc starts with the short jump but it kinda "trailblazers" for a longer arc as the air itself becomes conductive. This is why slo-mo lightning strike videos seem to show a pilot strick just before all the other electricity dumps into the same path and prolongs the strike. This is also why an artificial arc started at a short distance can maintain a current over a longer distance but can't simply resume that arc when current is interrupted/restored. The "path" of ionized air has dispersed.

  20. Aw man, I feel really bad now, because I now realize that I have been abusing a light switch for years!
    I thought I was a genius when I found out how to turn off the lights in my bedroom late at night without risking waking up my little brother, but I've apparently been hurting the switch all along!

  21. Nice video. For something fun, do a google on GE "silent" switches (there were a few other brands as well). These switches were truly silent. When you flipped the toggle lever, it tilted a little vial of mercury which would either make or break the contacts. As such, the switch had to be mounted upright and reasonably level.

    As the dangers of mercury and proper disposal became more realized, these switches were banned from production. In fact, it wasn't until seeing Alec's video on how thermostats work that I found out that mechanical thermostats no longer use mercury switches (they always used to). I've had electronic thermostats for the last couple decades and missed this change of the industry.

  22. I was testing my ebike motor a while ago to make sure it was functional before putting everything together. It's a 450W 24V motor. I connected it up to the lead acid batteries, and it worked well, but there was quite a spark when it started up. It partially melted the pins on the plug.

  23. Solid state relay with capacitive buttons! No arcing, no movable parts – should last for ages! Mainly because you cannot find the damn button and to turn on the lights 😛 (and yes – the relay degrades with number of uses as well)

  24. Hello, Humans.
    Mysterio: People need to believe and nowadays they will believe anything.
    (Spider-Man Far From Home)


  25. You need to make video on dimmers. I can not make damn thing work properly. Either they make buzz sound or cause flicker.

  26. The trouble is that "sound designers" often have a different opinion what the customer expects how a switch must feel and sound.

    Just at the old (Rover) Mini and the new Mini. The old one uses real switches while the new one has designed switches which always feel broken to me.

  27. I live and grew up in a house that's also quite old. I can't remember exactly which year it was built (I'll have to ask the builder & owner, my grandfather, and correct myself by editing this comment later) and I just wish that all the light switches in the house were rocker switches (with the exception of a couple dimmer switches in the upstairs kitchen on the main floor and the living room in the basement) and that proper GFCI/RCD rules were being followed. Really, the only places that have a GFCI in a case where an outlet is near a water source is only in 2/3 bathrooms; the main floor one, which is across the hallway from my room, and a couple more in the bathroom that's connected to my grandparents' bedroom on the upper floor).

    Don't get me wrong, I enjoyed this video, just like I've enjoyed the vast majority of this clever and clearly hilarious guy's videos, and I honestly would love to know where he gets the ideas for some of his catchphrases to put into his script and his teleprompter, and therefore, his videos, that not only is making the video capable of educating you about something (whether it's an everyday thing or something you may use occasionally or may not even use at all), but also managing to definitely keep the video entertaining in the process that he makes me chuckle or laugh once or twice the first time I watch one of his videos. I just wish that Alec was already at a million subscribers (as of August 13, 2019) because, seriously, Alec, you are a true standup comedian genius!

  28. Electrical outlets have a rating for how much power you may use when.

    E.g. the German "Schuko" system (Type F):

    Above 500 Watt, a device must have a switch to turn it off before plugging.

    Above 2300 Watt, the device may not run continuously. At 3680W which is the rated maximum, you may not exceed 10 hours. Also a device >2300W may not be plugged at all, it may only be plugged in or out for maintenance purposes or installing/removing the device.

    That's why the most powerful household vacuum cleaners and space heaters all have 2300 Watt, you can't have more without a special plug system (like CEE). A modern dryer often has a rating of exactly 3600W, you don't unplug it often and it never runs continuous.

  29. I've always known that switches click to provide feedback (to signal that you performed the action correctly) but I didn't know that the click was actually a necessary side effect.
    Interesting stuff.

  30. The question to ponder is why its logical in the states for 'up = on' and in the UK for 'down = on' (light switches)
    and whats with the logic of calling a socket an outlet – I get the logic its just odd.

  31. Nostalgia Alert
    One (or more) of the houses I grew up in had mercury switches. Surprised no mention of them here.

  32. A switch is a length of flexible wood used in corporeal punishment.

    A switch is a person who enjoys adopting alternately dominant or submissive roles in sexual play.

    Switch was the name of an advertisement campaign by Apple Computer in the early 00s.

  33. You should probably do a video on hysterysis, it's the basic principle in action in this video and others like the thermostat.

  34. So a sort of related question… If i unplug everything from the walls does it save me any money on my electric bill?

  35. You touched on this subject around the edges…a primary purpose of the click, IMHO, is to verify if an operation has been performed. This is a subset of an engineering principle I first learned in the 1950's in a book about "feedback," which means keeping an operator informed of a machine's action. It's frustrating to press the ON button for a device and find out, perhaps much later, that it didn't turn on, it just made it look like it did. My stove, for example, can be turned "on", as evidenced by the red light, without heating up at all, if you don't wrestle the knob to a firm position. Feedback is important for making the interface between machine and humans work.

  36. i always wondered why the light switches never asked me to join them. now i know 💡 its cuz they are just too clicky

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