not many people have the luxury of
building a brand new smart home from
scratch getting to install every piece
of home automation technology imaginable
exactly how they want it many of us live
in older houses with electrical wiring
from the 1950s and a bunch of existing
light fittings already installed in our
ceilings and switches installed on our
walls does that mean we need to replace
these with ugly looking smart switches
or do we need to spend a fortune
replacing all of our lights with smart
bulbs well you can do that if you want
or you can use one of these smart relays
which work alongside your existing light
switches and your existing light
fittings to smartify them
a relay is basically a switch that's
turned on electronically by a sensor or
a smart home platform I'll go into a bit
more detail about how they work later in
this video but what's great about them
is that you can use relays for pretty
much anything that is powered
electrically not just lights you can
automate exhaust fans fountains pool
filters whatever you want in this video
I'm going to tell you everything that I
know about smart relays I'll show you
how they work I'll take you through some
of their pros and cons and things you
might need to be aware of and what
features to look for so you get the
right one for your house let's take a
look
foreign
[Music]
so what exactly is a smart relay and how
does it work it's time for some diagrams
imagine that you have a simple
electrical circuit like this one there's
a light switch and when you turn it on
it closes the circuit and the light
turns on
a simple relay is just an electrical
version of this switch
when something like a sensor smartphone
or home automation platform tells the
relay to turn on and it closes the
circuit and turns on the light that's
how a simple relay works and this is the
kind you'll be looking for if you want
to remotely turn on an electrical
Appliance there are many different kinds
on the market from small ones designed
to sit behind electrical outlets so that
you can remotely turn them on to a
bigger more industrial style one that
sits on a DIN rail and Powers whole
circuits like pool filters or I don't
know hydroponic lamp arrays
in the smart home World though we're now
seeing a lot of special relays that are
designed to work in conjunction with
existing switches these are really
interesting because you can place them
behind an existing light switch and use
it to make any light switch and light
bulbs smart
this now means that you can continue
using your old light switch as normal to
turn on and off the lights but you can
also use your mobile phone sensors or
automations to electronically turn on
and off those same lights
how the heck does that work let's go
back to our diagram and take a look at
how a normal light switch works with a
relay
you can see here that it looks really
complicated and there are wires going
every which way
I wired up one of these relays into my
test rig so that you can see what the
wires look like in real life it looks a
bit like something out of the movie The
Hurt Locker
it's the best way
one of these things
were your own dicer
now is probably a good time to throw in
a disclaimer you should not be messing
around with electricity or doing any
electrical work unless you are a
qualified electrician live electricity
is dangerous and if you do something
wrong you may explode you might kill
yourself kill someone else or burn down
your house even if it's legal to do your
own electrical work in your country it
may invalidate your home insurance if
you mess something up
call an electrician if you need
electrical work done
what was I talking about again oh yeah
smart relays and switches have lots of
wires and it can look pretty confusing
at first until you understand what is
going on and whilst every smart relay is
slightly different the concept generally
means the same and they work like this
first we need to provide a way to power
the relay itself inside the relay is a
tiny itty-bitty computer that
understands how to connect Wi-Fi or
listen to instructions from a smart home
platform this computer needs power and
that is provided by this electrical
circuit here
the next part of the circuit is what
allows the relay to understand whether
or not you've turned on the old light
switch when you flip the light switch
the relay detects a change in that
circuit and knows it needs to do
something
it then takes care of turning on the
light by closing the relay and
completing that circuit it's no longer
the light switch that turns the light on
and off it's actually the relay and this
is why you can also electronically turn
the light on using a smart home or your
voice assistant
did you see how awesome those diagrams
and animations were the lines moved
around and stuff this guy knows how to
use PowerPoint right
if you thought they were as cool as I
did then hit that like button down below
it really helps me out and whilst you're
down there hit the Subscribe Button as
well so you don't miss any future videos
I make with even better diagrams anyway
these smart relays do a very similar
thing to Smart light switches which I've
previously made a video about but have
the added benefit of letting you reuse
your existing light switches because
let's face it most smart switches on the
market today either look or don't
work very well
if you've got a very specific interior
design style and have a bunch of
beautiful ornate switches that look
freaking awesome on your wall that you
don't want to replace then smart relays
might be for you they're also better
than using smart like bulbs because
they're generally cheaper especially
when you have to replace a lot of them
and they don't lose connection to your
smart home system when someone turns
them off at the wall there are some
downsides though it may not be easy to
install these relays into the back of
your switches if there's not a lot of
room inside your junction box you don't
actually have to install them behind
your switch though they can go elsewhere
in your circuit and it may be easier to
install them in a wall or ceiling cavity
if you can get to it but that may not be
an option if you're living in an
apartment also a lot of these relays
need a neutral wire to work properly
which a lot of people don't have
available at their light switches
especially here in the UK If you're not
sure what a neutral wire is or why
that's important I've explained that in
a previous video stick around until the
end of this video and you'll see a link
to my smart switch video which explains
it all in more detail you also also need
to make sure that you pick a relay that
can handle the power rating of whatever
device you're turning on and off
different relays are rated for different
levels of current and if you get it
wrong well that's when your house can
burn down
some relays have special protections
built into them to stop them from
causing damage if they get overloaded or
too hot so check the specifications
before you buy one the specs should also
be able to tell you what other functions
are available for that relay some things
to look out for are power monitoring
which lets you measure how much
electricity is being consumed by
whatever it is that you're powering
you can then use this to figure out how
much that device is costing you to run
each day something that's becoming
increasingly important as Energy prices
start skyrocketing especially here in
the UK some relays might support dimming
as well this lets you dim and brighten
the lights using the physical buttons on
the wall
or using your smartphone and automations
different relays also have different
numbers of channels much like the number
of gang on a light switch this lets you
control two three or more individual
circuits from a single relay and finally
how are you going to communicate with
your relay I personally use home
assistant but you'll need to make sure
that the ones you buy are compatible
with whatever smart home ecosystem that
you want to use different relays Connect
using different Wireless Technologies as
well some work over Wi-Fi others use
zigbee Z-Wave or even Bluetooth there
are dozens of different combinations
available out there and they will vary
depending on the country you're in the
manufacturer you're looking at and the
features that you're looking for you
might have noticed that I've been
showing a lot of Shelly devices this is
not a sponsored video I bought all of
these products with my own money because
I think Shelly products are absolutely
fantastic I wholeheartedly recommend
them to anyone who is looking for a
smart relay solution
they even sell these replacement light
switches with special brackets that clip
onto the back of the switch and are
designed to hold the relays in place
they're so freaking cool
Shelley if you're watching this why not
reach out to me and consider sponsoring
a future video of mine I'm always
interested in getting high quality
products for free so that's all that
I've learned since I started researching
and using smart relays here in my smart
home are you using anything like this in
your home let us know in the comments
below
I mentioned earlier that smart relays
aren't the only way to reuse your
existing lights you can also look at
smart switches and you can find more
information about that in this video
here if you found this video useful then
please subscribe to the channel I
regularly release videos like these
about smart devices and home automations
in general by subscribing to the channel
you'll see when I put up a new video and
then together we can make your home
smarter