video presentation we looked at how many conductors could be installed in a conduit
using appendix E of the on-site guide we're going to continue to use appendix E but some
different tables to work out how many cables we can install within trunking we're going to
be predominantly looking at installing it within metal trunking where the calculations in the table
have taken into consideration the cables that are installed will take up 45 percent of the room and
55 percent of the room will be taken up by space when calculating cables in different types of
trunking enclosures say mini trunking this factor still applies 45 taken up by the room of the cable
and in that case the cable may have an additional sheath on it and 55 percent taken up by space
but by using appendix E of the on-site guide that has been taken out of our hands however we're not
interested in grouping at this stage grouping will be done separately in the design element of the
circuit however when you add more cables into an existing trunking you must take in consideration
how much additional space that the cable is going to take up within the trunking but also take into
consideration grouping with other circuits so for this presentation we're going to work out and use
the notes that i have produced in order to find out how many cables of differing sizes can be
installed into a trunking as well as selecting a trunking based on the circuits given so you're
watching this now and you're thinking that's all right for all Gary's students at Tresham college
i can watch the video but how can i maybe carry the calculations out alongside Gaz you can do that
by visiting the efixx apprentice hub look for the teachers corner click on that and the set of notes
that we're going to do in this presentation are covered in there under trunking calculations so
download that set of notes i'll have it in front of you and you can follow along this presentation
and further develop your skills level one level two or level three diplomas or City and Guilds
qualifications you're carrying out i'm gonna bring the camera a lot closer so we can look at the
calculations that i've got in my notes that you can download off the efixx apprentice hub so i'm
going to attempt to walk you through the wiring in trunking within my notes at Tresham college
or on the efixx apprentice hub in the teacher's corner when you get the trunking notes off they
are only about the wiring so the pre-learning that we'd have done at Tresham talking about different
types of trunking et cetera is missing from the notes we're straight into how to wire in trunking
and get the right number of cables on basis on what size the actual trunking it is itself
it's a missing gap on the first page that i'm looking at in the wiring trunking and the missing
pages the appendix needed in order to do these calculations is appendix E from the on-site guide
an appendix we've looked at before when doing cables in conduit systems so we're in appendix e
and we're going to scroll through to find the correct tables and we're going to be using
tables E5 and E6 okay so table E5 is looking at the factor for the conductors that we install
in exactly the same way as we did in the set of notes that we looked at when we were doing
sizing conduits so example being first of all we've got the type of conductors
whether they're solid or stranded okay and we know that in trunking and conduit systems we're
always working with stranded cables and then we've got the cross sectional area in column number two
so we've got solid at 1.5 and 2.5 which we're not going to use and then we got stranded from
1.5 all the way down to 25 millimetres squared the next two columns are talking about the type
of insulation around the conductors and i generally get for column three my learners
to write the words thermoplastic over the top so it's a thermoplastic pvc it currently says pvc
BS 6004 cables and if we write thermoplastic above them we know what we're talking about
and then the final column says thermosetting pvc which is an insulated material that we commonly
use around the conductors in steel wire armour but you can also get singles with thermosetting
pvc on them so for my notes i'm going to be concentrating in the section for stranded
and i'm going to be concentrating in the one for what is thermoplastic pvc the 6004 cables
so that's where we get the factor for the cables itself exactly the same as we did in conduit
and then what we do is we turn over to the next one which is table E6 and this is the
factors for trunking the big difference now is they're not really in a logical order for the
factors example being so if we look at 50 by 38 the factor for the actual trunking is 767
the next one down is 50 by 50 so we've moved up a size of trunking size of trunking however the
factor there is 1037 then when we go up to the next one we've got 75 by 25 the factor is 738
so they're not in a logical order for factors so in Gary's notes i expect you to find the smallest
trunking available during the calculations so you have to scan through looking at the actual factors
until you find the one closely matches the factors generated by the conductors so that will become
more relevant and apparent as we work through the notes itself so that's the appendix E tables E5
for the conductors and table E6 for the factor for the actual trunking so those go in here okay
so we've put the page numbers in these page numbers will change every time the on-site
guide is updated but we're looking at table E5 and table E6 in order to complete those missing gaps
so okay let's move on to the next page the page here has an example on it so if we pull down
the actual page and the efixx download area you'll see it's exactly the same page it's an example
example here so what we're looking at is 50 by 50 trunking so i take these cables out they were
there for just visual purposes so we take those out this is a 50 by 50 metal trunking the most
common trunking that we use in the electrical workshop and that's what it's talking about as
well as this size of conductors here and they're all the same colour wouldn't expect them to all be
the same colour it's what i've cut off a bunch and these are 1.5 thermoplastic pvc stranded
conductors and the example says to you how many of these do you think that you can get inside the
actual trunking itself and not exceed the capacity okay so the capacity meaning the cables will take
up 45 percent of the room and air will be left for 55 of the room so that's example number one
so we're going to work through that one together okay using the on-site guide
in appendix E so let's see what we're going to be doing so the first thing says okay let's read the
question how many 1.5 millimetre squared single core thermoplastic stranded cables do you think
you can get in a 50 by 50mm trunking so how many do we think we can get in there it asks for an
estimate so i'd like people to have a guess at this stage so estimate or guess how many cables
you think you can get into there hopefully you'll do that and then it asks you by step by step
to work out what you're using well we're going to be using the first table is E5 E5 being the
factor for the actual conductors don't get caught out by using the ones for solid let's drop down
and look for stranded and it's 1.5 mil stranded thermoplastic is 8.6 okay so 8.6 so the next bit
the gap here that is in your notes requires you to put 8.6 in there obtain the factor for the cable
to be installed if they're 1.5 millimetres squared we know the thermoplastic we've inserted 8.6 the
next stage requires us to use the next table the next table being E6 and we've got to look
for the factor for 50 by 50 mil trunking so 50 by 50 is just here that's the trunking dimensions it
has a factor of 1037. if you remember back to our conduit calculations you can think
yourself hang on i know what Gaz is going to do next he's going to take that number there 1037
and he's going to divide it by the factor for the actual cables itself which was 8.6 you're
right that's what we're going to do and that will tell you how many 1.5 mil cables can go in so as
we come down to the next section divide the cables or factor of 8.6 into the trunking factor of 1037
then we do the calculation the calculation as i just said was 1037 divided by 86 and that will
give you the total number of cables that can be installed and the cables say that you can install
120.58 cables okay well we can't install 0.58 of a cable but maths it's gone beyond the five after
the decimal point can we round up no exactly the same as what we said when we were doing
the conduit calculations on a previous video you always have to round down meaning the total number
of cables that can be installed inside here a 50 by 50mm trunking if they're 1.5 millimetre squared
thermoplastic stranded conductors is a hundred and twenty if you install 120 cables in here
you haven't gone beyond the 45 space factor taken up by the actual cables itself it's nothing to
do with grouping remember if you put that many conductors in there in a calculation for design
you would have had to suggest that they were grouped together with a certain number of circuits
so that's the example that we need you to fill out whether you're filling out in Gary's notes doing
maybe some distance learning or whether you've downloaded it off the efixx apprentice hub that's
the first calculation estimate and then i've walked you through how to do it just quickly recap
table E5 factor for the cables 8.6 factor for the trunking was 1037. you did 1037 divided by 8.6 and
we got an answer when rounded always down to 120 cables that can go inside a 50 by 50 mil trunking
let's turn to the next page the next page is a problem so i'm not going to work you through
the problem you're going to do this yourself all of my problems generally then the first one is
going to be very similar to what we've just done let's read the questions how many 1.5 millimetre
squared single core thermoplastic stranded cables can be in this time 100 by 100 mil trunking so if
we go back to the on-site guide we're going to use exactly the same factor because we're working with
1.5 mil cable so we use the same factor but it requires you to look up a differing factor for
the trunking in E6 this time you're looking at the one for 100 by 100. so again look down here
look down here until you find the hundred by hundred then you get that factor that will
be the one that you're working through then as problem number one problem number two four mil
cable 75 by 75 you attack that problem and then we go on for example number two in the next part
of the presentation so for the next part of the presentation uh we've got example number two i've
worked for example number one it will always be easier having a handout in front of you because
obviously you're trying to see what i'm doing on the screen if you're working with your handout
from my notes or you've downloaded it or you're looking at the one on the efixx apprentice hub
so if i scroll through on the efixx apprentice hub we've got the ones you've just worked through and
then we've got aha the example so we've got the example there as well so you've got it in front
of you we can look at it at the same time this time there is slightly different they've got
differing circuits or different cable sizes within it and we've got to choose the trunking based on
the circuits we've put in it so we're going to use the information we've just used here
i'll read it to you hopefully you've got it in front of you as well select the trunking that can
contain the following single core thermoplastic pvc stranded cables if i had 12 1.5 if i had
10 2.5 millimetre squared and eight four millimetre squared thermoplastic pvc
cable so they're all in millimetre squared they're all thermoplastic pvc and they're all
stranded so before we do anything else we know that we're going to be working in table E5 we're
going to be using stranded and we're going to be using the thermoplastic factor for those cables
and we're going to now have to pick the numbers here of these that we've got so how many one fives
fours etcetera so let's see how that's going to break down when i've moved down my table itself
so select uh table and you'd insert that E5 E5 will give you the following so we've got a factor
according to here according to table E5 we've got a factor for 1.5 mil cable of 8.6 a factor
for 2.5 mil cable of 12.6 and a factor of four millimetre squared cable of 16.6 so in your notes
you'll first of all position those cable factors in and then we're going to multiply them by the
number of those conductors we have so we were told in the question we had 12 10 and 8 so 12 10 and 8.
so that's what we're going to do next we're going to multiply them to the number of conductors so as
we bring that down or look at a little mistake in my set of notes hopefully it's been corrected in
yours so we've got 1.5 millimetre squared cables have a factor of 8.6 which will be missing in your
notes and you need to insert it multiplied by the number of conductors 12 and when you do that in
the calculator i'm going to show you that this is the example the calculation so we do 8.6 times 12.
i got 103.2 i then did the 2.5 factor of 12.6 and multiplied it by 10 to get 126. and then i did
the four millimetre square cable with a factor of 16.6 and multiplied it by eight he had 132.8
and when i added those all together i got a total cable factor of 362. okay so i've gone quickly
through these calculations you can always pause it take a breath etcetera so what we've got there
is the total factor for the cables and now we need to use table E6 in order to work out the smallest
possible trunking to install those so let's have a quick look at that so as we go over to table E6
we're now looking well the first one's okay so we've got to look it's got to be equal to
or greater than this value so it could be 362 or bigger well the first one is 50 by 50
is 767 so we'll choose that one but then when you look around a bit hang on that's lower so 75 by 25
is 738 so you've got to come all the way through and just have a little sneaky look that there's
no others okay so no i think the smallest factor which is equal to or greater than this number is
actually 75 by 20 has a factor of 738 so as we come down here the bottom section using table
and there's a missing gap table E6 we can see the factor for must be equal to or greater than
362 so we worked it out at 362 and we found that the trunking factor of 738 738 was the trunking
75 mil by 25 mil was the trunking selected and becomes the answer so that's how we do a
calculation where we've got a number of conductors of differing sizes in order to work out the size
of trunking you could install a bigger trunking don't get me wrong you can install install any
of the trunkings in here but the questions are designed for you to select the smallest
possible trunking based on the factor that you get when you get the actual cable calculations
so let's turn over and now you can see i'll come cover some of the answers up you've got a problem
to problem three to solve very similar one we've just looked at a number of conductors of different
sizes so it's exactly the same as example worked through the same way and then we got another one
problem four does exactly the same but becomes a little bit more tricky from the point of view
it now only tells you what the circuits are so example being you've got um let's read it to you
pvc trunking that contains the following um cables of single core thermoplastic pvc strand you have
nine lighting circuits 16 A2 radial circuits and 12 A3 radial circuits so let me just confirm
that so that's nine lighting circuits that i say let's see nine lighting circuits i'll give you a
little clue i've been a bit sneaky so there'll be i went with one line one neutral and one cpc
for those nine lighting circuits and then i went there a 1.5 so you've got to be careful
your numbers A2 radials A2 radials record into Appendix H would be wired in four millimetre
squared but you'd have a line a neutral and a cpc for each one of the circuits there's 16 circuits
an A3 radial that would be wired in 2.5 and again you've got 20 of those but you'd have
a line a neutral and a cpc so i've been a little bit creative with this question here this problem
the answers are all on the efixx apprentice hub as well under the teacher's corner section at
the bottom to do yourself checking but i've just been a little bit creative with that one that's
the one people tend to get the hump with me in the class because i don't give them that little
sneaky bit of information beforehand so just be careful with that question and that takes us to
the end of that set of notes so i've done you a whistle stop tour of how to find the
factor for a trunking and a factor for cables in order to size the trunking in relationship
to appendix E when we're using tables E5 and E6 as always i hope this video has been some help