so this is the third in the series of installation theory recap videos where our pvc conduit exercise
so what did we learn when we're installing this job that can be moved forward to those instec
exams coming up we've installed a pvc conduit exercise pvc conduit comes in a standard three
meter length and these comes in the four standard sizes discussed in steel conduit in other words
the diameter of the conduit itself we're talking diameters of 16 millimeters 20 millimeters 25 and
32 millimeters being the four standard sizes we installed heavy gauge high impact pvc conduit
heavy gauge mini can withstand the blow from a hammer heavy gauge meaning the thickness of the
walls and we discussed in the classroom about light gauge pvc conduit and its applications as
well we installed a ring final circuit using the basic principles laid out in BS7671 for a ring
final circuit in a domestic dwelling so we use the same principles in other words we had a 32
amp circuit breaker in the distribution board we used pvc in this case singles but they were 2.5
millimeters squared and there was two of them because they were wide in the form of a ring
we had an additional socket outlet taken from the ring final circuit so we had three sockets one two
and three that were on the ring final circuit but this was taken from the ring flow that is a
spurred socket outlet and it's a non-fused socket outlet and we said in the classroom that you can
have as many non-fused spurs as you can the points on the ring so in other words we have three points
on the ring so we could have three non-fused spurs from that ring final circuit if we installed a
fused connection unit fused connection is similar to this one but this isn't on the ring a fuse
connection unit which has a maximum rated fuse inside it of 13 amps we installed one of those
in circuit we could have as many socket outlets spurred from that point forward as we wanted
so from a fused connection here how many socket outlets can we have spurred an unlimited number
because the limiting factor being the 13 amp top fuse installed within the connection unit itself
we know under the 17th edition wiring regulations that socket outlets rated at 20 amps and below
must be additionally protected by an RCD rated at 30 milliamps or less and we have a
30 milliamp RCD be fitted within our consumers unit we know as we move towards the 18th edition
that's going to be socket outlets of 32 amps and below must be additionally protected by an RCD
rated at 30 milliamps and below we've installed 13 amp socket outlets on our installation therefore
they are additionally protected by an rcd rate of 30 milliamps or below we know the disconnection
time when five times the current is found which is 150 milliamps is 40 milliseconds and we went on
and performed that test in the classroom we know with any pvc so when we looked at pvc twin and cpc
cables in the classroom as well as pvc conduit we must install it in a temperature above zero so in
other words if our conduit was laid on the floor overnight froze overnight and we turned up at the
installation we could not install our pvc conduit we must wait for 24 hours with our pvc conduit in
a temperature above zero so we'd have to bring it in perhaps inside the building leave it for
24 hours before installing it we know that pvc stands for polyvinyl chloride as well on this
installation we've used spacer bar saddles and we know in BS7671 it says a space of our saddle
must be supporting the conduit within 300 millimeters of bends sets and accessories
and we've done that on our job so this distance here must be within 300 mil as much this distance
here be within 300 mil to support the conduit itself on this installation we've installed
black pvc conduit because we're simulating industrial style installation however we are
aware the fact that we have white pvc conduit as well and we would use that perhaps in offices
where it's more aesthetically pleasing to see a white conduit a consumer we've installed here
offers basic protection in other words we need a tool or key to enter the electrical enclosure also
once we've entered the electrical enclosure there is a barrier over the bar which is live behind
it offering basic protection we also know that we can't physically touch any of the terminals
within the consumers unit again offering basic protection and we know and we've talked about it
previously about the IP rating of an electrical enclosure being IP4X on the top surface
and IP2X on the sides bottom and front when the installation is complete we installed a radial
circuit for the smoke detector from a fuse connection unit we changed the fuse in here
to a three amp fuse we installed a 20 amp type b circuit breaker wiring 2.5 mil cable to feed the
fuse connection unit we selected as previously stated a 20 amp device here because we wouldn't
want to use a 16 in case this had a 13 amp fuse in and we wouldn't therefore guarantee discrimination
a word that will be changed under the 18th edition to selectivity between our over current protection
devices in other words if the load here had a 13 amp fusion doesn't in our job but if it did and we
only had a 16 amp fuse here and there was a fault on the load we couldn't guarantee the fuse within
here would operate before the one in the consumers unit therefore not having active selectivity and
therefore failing the system in that regards so in other words if we have a 20 amp fuse here and a
13 amp fuse here the ratio is closer to two to one which we're looking at as a rule of thumb in order
to get active discrimination or selectivity depending on when you're watching the video
we installed a number of different fixing methods we used both male and female adapters to connect
to our boxes and we state the fact that where we enter things such as our tee box down here that we
would need to glue the conduit into place we would need to take all the precautions when using glue
so in other words read the instructions be in a well ventilated area wear PPE such as goggles
gloves and a mask and those are questions that will come up in our exam when looking at gluing
conduit in situ we had to bend the pvc conduit ourselves so we were putting nice smooth 90 degree
bends in and we said as previously stated that the bending rates of conduit is 2.5 times the diameter
of the conduit itself we've been working here with 20 mil conduit therefore we multiply that number
by 2.5 to get 50 mil we set our compass up we draw a circle with a radius of 50 mil and that gives us
the tightest bending radii that we can have on our conduit and we were looking to be slightly
bigger than that when we pulled ours but again the exam will say to you what is the factor used
to work out the bending rates of conduit and it's 2.5 times the diameter of the conduit so that's
covered some of the recap points required for our installation theory when installing such systems
as plastic conduit plastic conduit for recap pvc stands for polyvinyl chloride comes in a standard
three meter length comes in four standard sizes and it's the diameter of the conduit 16 20 25
and 32 mil we use high impact we know it must be installed in a temperature above zero if it
was installed below zero we've got problems with it shattering or breaking if it was left outside
overnight it would need to be left in ambient temperature above zero for 24 hours before we can
install it we know that our ring final circuit has additional sockets taken from it our fuse spurs or
non-fuse spurs we need to work out how many we can have in relationship to the circuit so non-fused
spurs can be taken from a ring final circuit to the maximum number of socket outlets on the
circuit in other words if there's 10 sockets on a ring final circuit you can take 10 non-fused spurs
one of each of the socket outlets where we install fuse connection units the maximum size of fuse
in there is 13 amps from that position onwards you can have as many socket outlets as you wish
we know that a ring final circuit or a socket circuit rated at 20 amps and below under the
17th edition remembering that's the rated value of the socket fronts and these are rated at 13
amp so that's quite key to me i've just had some sound issues i've had to come back and reshoot
this part of the video again that's quite key to us that these socket outlets are rated at 13 amps
nothing to do with the size of the overcurrent protection device within the consumers unit
under the 17th edition all sockets rated 20 amps and below need additional protection by
an rcd rate of 30 milliamps or below as we move towards the 18th edition they're going to change
that for socket outlets rated at 32 amps and below need additional protection by an RCD
rate of 30 milliamps and below it's the value of the sockets rated not the rating of the fuse
within the consumer unit that will distinguish whether or not i will need an RCD protection
on it and that RCD rated at 30 milliamps and below disconnecting within 40 milliseconds when there's
five times the current present in other words if there's a 30 milliamp RCD protecting the circuit
it will have 150 milliamps under test and disconnect within 40 milliseconds or below
real key points as we move towards level three hence i've reiterated at the end of the video
i hope this video has been some help