so we've completed our radial circuit in steel conduit wired 2.5 millimetre squared PVC single
insulated conductors for all conductors including the CPC and we're moving on to carry out our
continuity of CPC and polarity test remembering first of all for the polarity part of the test we
need to prove the line and neutral pin and follow it by doing the line and earth pin within the
socket outlet itself it's slightly different than the socket circuit we wired previously as a radial
the one above me because we've now created a parallel earth path by the steel conduit so the
exposed conductive part will lower our reading for continuity of CPC but i want to prove the
conductor from source in this case to the furthest point and only point on the radial circuit is
continuous before we introduce the parallel path which also is connected to earth so there'll be a
small twist on our continuity part of the test which we'll look at in this video first of all
i need to set up my tester in order to carry out a test between line and neutral as part polarity
so what i'm going to do is cut to a previous video presentation on how to set up my test instrument
and then we'll get on with testing between line and neutral as power polarity then we'll
do continuity CPC looking at both the conductor and the parallel earth path in this presentation
carrying out a continuity test on a socket circuit we're likely to be using the socket adapter lead
within our Megger MFT box we are going to need to remove the resistance of these and we
in both cases whether you're testing a ring final circuit or a radial socket circuit we actually
test between line and neutral first so we're going to need to use the red and blue leads and remove
their resistance as part polarity during that test and as stated before we're definitely going
to have to use the red and green sections in the top of the Megger MFT because it's a continuity
test blue one i'm going to put into the green section and the red in the red section and we
now need to remove the resistance of this lead so we need to short together the line and neutral pin
here previous presentation i showed you using a knife you could use a crocodile clip you could
use a coin or something metallic so i'll short those two pins together i see we have a reading of
nought point nought seven press the test button once and i've removed the resistance of the line
and neutral for a continuity test in this case it's part polarity the continuous CPC requires us
to move the leads across so that's testing between line and neutral to complete any test on a socket
circuit we need to test between line and circuit protective conductor so i swap my leads over now
and i now need to remove the resistance when carrying this part of the test between
the line pin and the earth pin so link those two together once again we've got zero before
we press the test button once we have a reading if i press it again we've zeroed
out the leads itself and we're now ready to test between the other two conductors
i've stated in two uh previous presentations ring final circuit and radial socket circuit testing
why we're doing both of those but that shows you how to zero out our longer lead with a plug top on
it during the continuity tests so i'm set up and ready to test between the line and neutral pin as
part to polarity i complete the polarity test by testing between the line and the earth pin
when the CPC is connected by proving two of the three pin positions we actually proved polarity
of the socket outlet itself the instrument is set up and we're ready to test i've also linked out
the line conductor and neutral conductor within the consumer unit and remove the resistance of
the leads themselves let's see what reading we get when we test between line and neutral
one that we won't record on our test paperwork and is purely part of polarity testing
i've got a reading of 0.03 just prove the switch works
full scale deflection so i've gone to an infinite reading
and back to 0.03 won't record that reading it's part polarity let's look at testing between the
line and CPC in the next part of the presentation so we're ready to carry out the continuity of CPC
test and complete the polarity test i've changed the leads over in the top of the Megger MFT i have
got another subtle difference i've actually disconnected my CPC from my earth bar in my
consumer unit i need to prove that the conductor the CPC and the line conductor make their journey
to the furthest point on the radial circuit so i've disconnected it from the earth bar i
will return it to the earth bar but when i do that and repeat the test i will introduce the
parallel earth path created by the steel conduit first of all i need to prove my conductors get
to my furthest point and i'm not relying just on the exposed conductive part to make my connection
to earth hence we've disconnected the CPC in the consumer unit i expect this reading to be the same
as our previous reading for testing between line and neutral because the conductors are
2.5 so we've got 2.5 CPC and a 2.5 line as we did when we tested between line and neutral
0.03 exactly what we expected turn it off
turn it back on so that means for me i've completed the continuity CPC test and proved
polarity however i need to introduce the exposed conductive part now to prove that is connected to
earth and see what happens to my reading when i return the CPC to the earth bar in the next part
of the presentation so i've connected the CPC back into the earth bar meaning now we've got both the
2.5 millimetre squared PVC single the metal clad box the metal conduit and the metal clad socket
as a parallel earth path so we've got the conductor and the exposed conductive parts
being the earth path therefore expect the reading to be less than 0.03 that we got the first time
possibly it's going to be just zero the instrument won't be able to read as low as it
is going to effectively be between the two points let's put it on and see
we've got zero if i've invented a resistive free circuit i'm probably gonna be a billionaire
overnight i haven't the instrument can't read as low as the reading is operate the switch
full scale deflection we've completed the polarity test by testing between line and
neutral and line and CPC we've proved the circuit protective conductor when it was disconnected gets
to the furthest point of the radial circuit and we've introduced the parallel earth path
to show that that will lower the reading for our continuity we will record the highest reading 0.03
as our R1 plus R2 reading we can tick the polarity box as well we could also carry out
a long wandering lead test from the earth bar to prove the exposed conductive parts
in circuit are connected to earth we're going to do that in the next part of the presentation i'm
going to use a video that i set up the wandering lead with previously so i'll cut into that next
and then we're ready to carry out that test next one to zero out would be if we were using a long
wandering lead it could be that we are testing the protective bonding conductors continuity
or we're just doing an R2 test at different points in the circuit i've fully unwound this off camera
and checked that there are no nicks and splits in it but for the presentation purposes i've
wound it back up because obviously trying to get it on the desk is quite tricky there's a
huge amount of cable here there's 50 meters so all of that will need to be removed i've put my probe
into the side here so i'm using my green lead so it's into the side of the wandering lead
and we've got the probe connection that comes with the actual wandering lead itself which will go
in this case into the green section the top of the Megger MFT and as always we'll use the
red one in the other hole so exactly the same as previously stated and again we've got two
crocodile clips so i want the maximum surface area to maximum surface area in that position a
little squeeze and we see we've got a reading this time of 0.93 press the test button once
press the test button again so this time we've now gone down to zero so i've zeroed
out that 50 meter long lead allowing me to go off to do R2 testing or continuity of a
protective bonding conductor so i've set up my long wandering lead i still get my learners to
set up the long wandering lead even though they could use the two very short leads actually in
the tester because the job is very small i've connected one end of it to the earth bar i've
zeroed out the leads and i've got the other probe which i can go around and probe on to the exposed
conductive parts to prove they're connected to earth so connect onto the conduit itself
i've got a reading of zero but we explained that earlier so yep that's connected to earth
conduit got reading of zero and the metal cloud socket outlet itself i've got a reading of zero
so we've used a long wandering lead easy for me to say in order to prove that the exposed
conductive parts are also connected to earth i hope this video presentation has been some help