for this presentation we're going to look at the three plate loop in method this wiring method is
used extensively in domestic dwellings and we will replicate here in a very small job on those people
who look at anything that's tiny and that doesn't mean anything when we look at domestic dwelling
but from the consumer unit in this case the batten lamp holder which could be ceiling rose and
pendants it's just easier for us to position on a wall a batten lamp holder and one way light switch
one way light and one way light switch what we're trying to replicate is the consumer unit supplying
say the first floor bedroom number one controlled by one switch bedroom number two controlled by one
switch bedroom number three controlled by one switch and it's the best way in which we can
show the wiring practices in a three plate loop in method so let's point out some of the other
obvious things we've got a metal clad amendment three two way distribution board so inside here
we've got a circuit breaker rated at six amps and it's a type B for domestic dwelling which is over
current protection for the lighting circuit we've got the lighting circuit in this case of college
in one millimetre squared twin and CPC cable in industry that could be one point five we end up
thrown cable away so we're obviously in a throw away one mm2 cables and not one point five the
general rule is they tend to like to the 1.5 in industry because the amount of thermal insulation
are in walls and in roof spaces and we'll cover that in a later set of notes in the classroom
I've dropped all the covers off so in our than the individual connections within the consumer unit
the one way light switches and the batten lamp holders to get this three plate looping method
the inside my consumer unit I've got my PVC PVC between the CPC cable with my brown line conductor
my blue neutral conductor and my green and yellow circuit protective conductor
and they are terminated the brown line conductor in the top of the circuit breaker which is rated
at six amps of type B for domestic dwelling a solid neutral bar would have matter which hole
I chose but I'm going to choose it in exactly the same position on both bars so on the neutral bar I
chose the top connection for my neutral and on the earth bar did the same I chose the top connection
for my circuit protective conductor and they go out and supply the first lighting point so we'll
see how those connections going to the actual batten lamp holder or ceiling rose and pendant
so this cable here is the one from the consumer unit and is bringing the supply in it's only what
under half a meter on my installation that could be run many meters through a domestic dwelling
from the consumer unit to the first lighting point which we've got here the cable coming down here
is the one that comes down to the switch in say the bedroom so we've got the cable coming
in this time for the consumer unit and the cable going down to the switch and the switch is a one
way switch and now we're gonna have a look at the connections that we've got here within our 3 plate
loop in method within the batten lamp holder itself so lets have a look a the connections
are in the three plate loop in method so we've got the cable coming in this time from the
consumer unit bringing a permanent brown line a blue neutral and a circuit protective conductor
the one going down to the switch in this case is a twin brown and CPC so see how those connections
go let's start first of all with the supply cable from the consumer unit the brown line conductor
comes in and is one here that goes into the loop terminal this is a solid brass block of three
of which is not connected against the lamp so the outer block here is connected to the the lamp via
the batten lamp holder and here the centre block the loop block is not connected to the lamp and
brings in a permanent line connection what we do then with the cable that goes down to the switch
which is twin brown we take one of them out the loop terminal which is permanent line down to the
switch when the switch is turned on it brings back a switching line connection which is connected
here against the lamp giving you control in order for the lamp to work the other side must have
a neutral connection which it comes in from the supply cable the neutral goes into the
neutral block which is also a block of three and is also connected to the side of the lamp itself
we also have protection so the CPC is terminated here into the earth terminal itself
so what we've got then is the supply cable brings in permanent line neutral and CPC the line goes
into the loop terminal doesn't matter which one it is one of three doesn't matter which
one he goes into we then bring down a twin brown down to the switch which it has a permanent line
going down to the switch we operate the switch it returns as a switching line and turns on the lamp
that needs a neutral on the opposite side in order for it to work and we need protection virus
CPC we can see it the first lighting point the twin brown coming down with a CPC so a twin brown
CPC coming down we've got one that we know he's permanently connected to line because you came
up the loop in terminal above and one that returns is our switching line and is connected against the
side of the lamp to in order to have control over it the CPC is also here and secured in the back
of the box this is a plastic enclosure so the CPC there in case we change this for an exposed
conductive part which we'll cover in other videos in order to continue this on to the next bedroom
say or other room within the dwelling we need to take out the other side here in this case
another permanent line from the loop connection a neutral and CPC to continue the process on to
the next room so whereas we brought in from the consumer unit permanent line
neutral and CPC if we were to continue on and this isn't the last point on the lighting circuit
we need to take out a permanent line from the loop terminal a neutral and the CPC to repeat
the process in the next room here we can see both lighting points one so bedroom ones light in point
and comes down to bedroom ones lights which we've come across into the next room and we said that we
brought in this cable a permanent line neutral and CPC the line connection makes its way into
the loop in terminal the neutral from this cable goes into the neutral block and the CPC from this
cable terminates into the earth terminal we then repeat again the same process this cable here is a
twin brown and CPC so we bring one of the brown conductors down from the loop in terminal down
and when we come back in the other brown conductor it becomes a switching line and
is connected across the side of the lamp in that terminal just there the CPC's terminated in the
earth terminal and then we see we've repeat the process we go into the next room so we obviously
carry out anything outgoing cable a permanent line from the loop neutral from the neutral connection
and a CPC from the earth terminal to the next and final room so in our final lighting point for our
circuit ours only has three on it this cable here is supplying this light in say bedroom three and
brings in a permanent line connection which goes in the loop in terminal it brings in a
neutral which goes into a neutral connection and it brings in a CPC which is terminated
into our earth terminal I've changed the cable now down to the switch from twin brown the CPC
to a more traditional twin and CPC industry tends not to use much twin brown because it's
more expensive than using twin and CPC cable so if we do use twin and CPC cable here to go down to
the switch our conductors will be blue and brown however the brown conductor will be coming out of
our loop terminal and bringing a permanent line down to our switch however our switching return
conductor which is now blue in the cable needs to be identified with brown sleeving and positioned
across the other side of the lamp as a switching live conductor and not a neutral it also brings
through CPC which is terminated in the earth terminal at this point we've stopped our light
in circuit but you could continue on to more rooms within the installation it's not limited to three
so switches wanted to had twin brown going to them and they were one-way switches only
one way of turning on the light in that room so this again the third point is also a one
way switch at this time I've used twin and CPC cable so the brown connection comes in
as our permanent line when we operate the switch we send a switching line conductor up to turn on
the lamp itself but this time it is blue and not brown or identified it with brown sleeving because
it isn't a neutral conductor it's a switching line conductor along with the lesson in the workshop
we can see here the three plate loop-in method the supply in this case from the consumer unit
travels a short distance but in industry could be some distance so for the terminations in new
consumer units are made our cable runs into this case lighting point 1 dropping off the permanent
line in the loop in the neutral in the neutral termination and the CPC in the earth termination
we take down from the loop in terminal a permanent line down to this case of one-way switch
the switching line returning those against the side of the lamp in order to turn on the lamp
and have control we repeat the method we bring out a permanent line from the loop neutral CPC
across the the second room the permanent line goes into loop the neutral and CPC connections are made
and again we bring down permanent line down to the switch and a switching line to return we keep
replicating that throughout the installation in order to gain one way control in each of the rooms
bedrooms are the best way to look at it I'll also go through two way and two way and intermediate
in other presentations but this is the basic principles at the three plate loop in method