so early on in the workshop i'm going to expect us to do some wiring diagrams to help us
with a one-way lighting circuit how many times have we walked into a room
operated the light switch and the light has come on in from one position so that's what
we're going to do here we've got one light switch controlling one light we've got a picture now down
here of a consumer unit we've got a ceiling rose and pendant so we've got one of these
ceiling rose and pendant and we've got a one-way switch here so we've got a light switch here
however the connections even though this is a wiring diagram won't be exactly the same in the
consumer unit when we wire it up we'll be very careful to select the appropriate terminations
for those but the connections in the ceiling rows or batten lamp holder and the one-way light
switch will be identical from this drawing as it will be when we get into the workshop
for this drawing we're going to use pvc pvc twin and cpc cables for all the cable runs so we're
gonna have a brown one a blue one and a green and yellow and at the moment we know that we need to
add the green and yellow sleeve in order that we can identify our circuit protective conductor
the brown one we're so used to calling our line conductor the blue ones are neutral and obviously
our cpc but in this drawing we might find that now the blue one is going to be identified differently
and called a different conductor as well but let's first of all concentrate on the cable
from the consumer unit to the actual light fitting itself the light fitting itself has some several
blocks in here and these are separated from each other so there's a block of two
a block of three and a block of three here they're insulated from each other so this
block of two is not connected to the block of three and this block of three in the center is
not connected to this block of three here so let's have a look at that in here so what we've got is
we've got a block of two so that's a brass block with two terminating holes in it
a block of three which is our loop terminal we've got three holes in it and again it doesn't matter
which ones we go in when we use the loop but we've got a block of three and then we've
got a block here of three which is neutral and again it doesn't matter which ones we go in we
see already in this case we've got a brown one which is a switching line to go to the
actual lamp holder itself and a blue connection for our neutral to go to a lamp holder itself
if we look at a ceiling rose pendant we've got exactly the same scenario going on you've got a
block of two which is our switching line with a brown one going to the actual lamp holder itself
you've got a block of three which is our loop and a block of three which is our neutral with one
of those going to the actual lamp itself exactly the same here two three three switching line loop
neutral and it's how we use those in order to make the connections for this lighting circuit
i'm going to start by doing the cable that comes from the consumer unit to the light itself
and we're going to be using this one here we're going to be using the workshop
one millimeter squared pvc pvc twin and cpc cable on site lighting circuits can
often be wired in domestic dwellings using 1.5 millimeter squared cable
we're going to talk through the connections as we go let's start off with the line connection
in the consumer unit which is going to come out of here this is the symbol for a fuse and is often
shown in exams in multi-choice conditions what is this symbol that's the symbol for a fuse this one
here is a symbol for a neutral link and this is our earth bar where our cpcs will be connected
when you do your drawings for me you're going to not be doing them free hand people will be
shouting at me Gaz you're doing them free and i am doing them freehand but we'll expect us to use a
ruler and line up appropriately so this cable here which is the permanent line connection is going to
come into the center here it's not going to come into these outside two these outside two as we saw
here had these flexible cables on them and we had a brown one that came out to the light fitting
we also had a blue one that came out to the light fitting as well this brown conductor
coming from the actual consumer unit will bring a permanent line connection in if i connected it to
this side of the lamp and a neutral to this one the permanent line will pass through the lamp and
through the neutral and illuminate all the time we want to gain control from the switch below so
this is where this center terminal of three called the loop comes in doesn't matter which one of the
three holes we use but i am going to use this one just here okay and i'm going to bring those two
together now you're going to do this way better than me in order that you can line these up okay
so my line cable comes in and is connected into the center loop terminal any of the three i've
chosen the first one that's the permanent line coming in as it's a twin and cpc cable
coming from there we can look at the neutral next neutral comes out of this in our case neutral link
i'm gonna find out where that goes this block here marked with an n of three of which one's already
got a blue cable going off to light fitting is our neutral so if i just drop that down to there
and i'll bring the two together like so so my neutral comes from my consumer unit from the
neutral bar not from the uh symbol here there'll be a neutral bar within your consumer unit
it comes up and is connected to this side of the lamp you can now see if we'd have put this
one this side a lamp would have illuminated and at this stage it won't because we put that into
the loop terminal we need a cpc i'm very happy in the classroom that we use just green but
some people like to use green and put a striking yellow down the side so let's bring a green up
and we're going to connect it into our actual earth terminal just there so let's look at
where that is in the actual batten lamp holder batten lamp holder there is our earthen terminal
it doesn't need a cpc in here believe it or not because it is fully insulated it's fully plastic
but we know these fittings can be changed in the future for metallic ones and a metallic light
fitting is an exposed conductive part and the metal work needs connecting to the cpcs that will
be left in here so that's a cpc terminal it's only got one in it this one's slightly different it's
got a brass block with two holes in it and again it doesn't matter which one you put your cpc's
in or out but there's two terminating points for that in this one we've only got one on our drawing
some people as i said do like to just put a strike down the side of it of yellow it still only makes
it one cable but it's trying to identify that as a cpc so in other words we've got the following
haven't we we've got our cpc identified as green and yellow throughout its run so it's just the
one cable pvc pvc twin and cpc from our consumer unit into our light fitting the permanent line
comes in and goes into loop the neutral comes from our consumer unit it goes into neutral terminal
and our cpc comes in and goes into the earth terminal in the back of the light fitting itself
that's our first cable we're now going to bring a cable down to the switch
so we're used to seeing our switches this is a one gang switch this is a one gang because it
only has one switch on it when we turn it over we've got the following we've got common and L1
sometimes shown that way round so we've got common in L1 doesn't matter which way round it goes it
just means that maybe when you turn it on that would be off you would need to turn it round in
order to get the right way around so if that's on and it actually was the on position but the light
fitting was off obviously you'd just spin it round so we've got common we've got L1 and we're going
to take those connections down there this is also fully insulated so there's no cpc terminal in here
but we will bring a cpc down because we know that this plastic light switch in the future
could be changed for a metal one and a metal light fitting is an exposed conductive part
for this drawing i'm going to show you taking a twin and cpc cable down from the actual light
down to the actual switch itself often in the workshop then we use twin brown
but lots of colleges don't so i'm just going to do this one where we use the same cable again
so at Tresham we might be taking down a twin brown and cpc but most colleges and
most electrical installations don't they actually use twin and cpc cable
but this now will not be a neutral this blue conductor will actually be a switching line
and needs to be identified accordingly let's put the cables in first the conductors on our drawing
in order to see where they're going to go so this cable comes down to our switch we're going to come
out the looping terminal there's two holes to choose from doesn't matter which one we take
but i'm going to take that one down from the center one and i'll take that straight into a
common i'm going to take down a blue cable which is going to come back from here but this is not
a neutral so it won't be connecting in here it's a switching line conductor so it's going
to turn this light fitting on so i'm going to connect these two together with a blue cable
and then finally the cpc terminal here to the cpc terminal here so the earth terminals link together
and again i know people do like to put a strike of yellow down the side of that one as well
so is it a neutral so the line comes down here the permanent line comes down here and
at the moment the switchblade is open when we close the switch so when we turn the switch on
this now comes down and brings the line onto here the blue conductor this is now a switching
line conductor so it's not neutral and needs to be identified as a switching line conductor
that means we put a little bit of brown sleeve in onto the actual blue which is not a neutral
in this case is a switching line conductor in order to do that we need to take a pen
and just put a little square around it to identify that with what is brown sleeving so
some brown sleeving on here and here so both ends both the switch and in the light fitting itself on
site you're going to often see a blue cable which isn't neutral which is identified with
brown sleeving as a switching line conductor and it's really important that we put those on
because we don't want to start confusing this and putting into the neutral connection itself
so let's go through those uh connections our permanent line comes from our consumer unit on
top of the circuit breaker so in other words where we're used to screwing it on top of the
circuit breaker it comes and is connected into the looping terminal the middle set of three
any hole doesn't matter we bring our neutral from our neutral bar in our consumer unit
and we bring our neutral into our terminal marked neutral there's three to choose from
it doesn't matter which one we choose and from our earth bar in our consumer unit
we bring our cpc into the terminal in the back of the light fitting ready in case it's
changed for an exposed conductive part so that's our first twin and cpc cable that we bring in we
then take a twin and cpc cable down to the switch we bring down the brown one connect it in common
as our permanent line connection our cpc into the back of the box gets fully insulated for us
and then this blue one which is not a neutral which is identified both ends with brown sleeving
as our switching line and we can see that once we've got a neutral this side of the lamp
and we close that switch our line connection comes through here down here close the switch comes down
our switching line and onto our lamp causing it to illuminate so if the switching line is
this side and the neutral is outside we end up having a fully illuminated lamp
that would be our one-way lighting circuit our basic first one-way lighting circuit i'm
going to ask you to extend this so in other words repeat the process so this is bedroom number one
and we're going to do another repeat of this so in other words you're going to screw another ceiling
rose and then have another switch and they're going to be independently working so in other
words in another bedroom to do that you've got to just move this cable effectively out of here
and into the next room so it might be that this cable came in from the consumer unit but then
the next one is going to go into the next room so the next room will need the permanent line
a neutral and a cpc and they will be gained from the looping terminal where the permanent line is
the neutral and the cpc so let's take those out into the next room the line cable comes out goes
into the next room the neutral will come out and that will go into the next room and then the cpc
will come out and that will go into the next room just put a little bit of yellow on that
so what's happened there is we've got this section here going to repeat itself when it enters the
next ceiling rose neutral into the block of three in this room the line permanent line into
the looping terminal of the next fitting the cpc into the earth terminal and next fit in and then
we drop down to the next switch and repeat the process so this here i would like you to put this
onto your drawings and say to the next room okay so we play here to the next room in order that
we can repeat the process so what we've shown here is the wiring diagram using twin and cpc cables in
this case one millimeter squared for us in order to do the wiring diagram of a one-way lighting
circuit from the consumer unit to the light fitting from the light fitting to the switch and
if you're lucky enough to extend your job you'll take another cable out to a ceiling rose down to
a switch and you'll keep repeating the process as always i hope this video has been some help
you