so we've completed our steel conduit exercise and we're now ready to test it we have two switches
two way controlling both lights so these two switches when turned on or off will illuminate
both light fittings at the same time we're going to carry out a continuity test at all points in
the circuit recording the highest reading wherever that is we're also going to complete the polarity
test by operating the switches as we go through the circuit itself we're once again going to use
our Kewtech adapter to make sure we get to the furthest point of the skirted batter lamp holders
in each case i've shown you previously how to set this up and no doubt at this point
in the video i've probably cut now so you can see how i set this up so the Kewtech adapter that
we're going to use in order to get to the furthest point of our bayonet cap lamp holder now on
our steel conduit job comes in a set of five and obviously you've got to choose the appropriate end
for the bayonet cap itself and we can see now we've got two terminals we're only going to
need to probe into one of those for this test so we're going to need to pick up the switching line
it won't matter which one we choose if we choose the wrong one we can either move the probe across
or we can turn it round in order that we get the other terminal however as always we need to remove
the resistance of anything in circuit before carrying our continuity test so if we set our
Megger MFT up as usual to ohms and as always on our one it's in the orange scale itself
i'm going to use a slightly older tip this time so i've gone back to a tip that i used
on an insulation resistance testing video that i did before more tip exposure these devices don't
allow us to plug in with the adapter like so we're trying to interface a Kewtech device with an a
Megger device and they don't quite work the throw isn't long enough here to make the pin itself
so to overcome that problem i'm going to use this style of probe
acceptable for the test there's no issues with it so i'm going to probe it into one of the
adapters and then i'm going to probe onto the other end in order that i can
work out that i have a circuit i have some resistance there that needs to be removed
so let's do that again so hold it on and i've got some resistance press the test button once
and i've got zero it's not flashing so therefore i've removed the resistance now of this q-tech
device that will allow me get to the furthest point i will confirm that my link is not broken
and i've got a reading of 0.03 i'm not going to remove that resistance i'm going to leave
that tiny bit in the circuit we've got is so phenomenally short every tiny little bit
of extra resistance for us will help so i'm not going to remove that resistance this time
but i've removed the resistance that was quite high in the Kewtech device that allows us to get
to the furthest point on our batten lamp holder we're now ready to use this kit in order to carry
out the continuity of CPC and polarity test of our steel conduit lighting circuit so with all
the resistance removed we're ready to get on with the test itself so we've been inserted into the
batten lamp holder our link is in place as always between our line conductor and this
case our earth bar haven't disconnected the CPC i've just left it connected we've removed the
resistance of our leads we've connected to the furthest point of the lighting circuit in this
case at this point we're going to move forward to the furthest point physically in circuit on the
second part of the test so i'm going to prove in the back of the fitting where the CPC is connected
that we have a connection to earth i've got a reading of 0.12 operator switch goes off
operate the switch comes back on operate the first switch again operate the second switch
comes on and off so we've proved polarity at this point however i want to prove that not only the
plastic light fitting gets the connection to the CPC that the back of the box does and the
conduit itself so i'm going to probe into the back of the box have a reading of 0.1 i could
operate the switches again now but i'm not going to and i'm going to probe onto the conduit itself
0.12 of an ohm so i've proved the CPC gets to the fitting the back box and the conduit
at the lighting point itself so now i'm going to move to the second lighting point on circuit
where possibly the reading will be higher because we are further away at this stage
so once again i've probed onto the cpc connection in the back of the skirted band lamp holder
and i have a reading of
i've got now 0.2 of an ohm so it's increased i am further away from the distribution board so
i've got a higher reading once again i need to operate the switches goes off comes back on off
on and we can see it doesn't matter which switch i operate that we have
the switching mechanism working for polarity so we're going to need to leave it in the on position
going to prove the back of the box has a CPC connection
it does again i could operate the switches but i'm not going to and the conduit itself
and at all times i remember in the highest reading that i've achieved at this stage
so i've proved that both lights come on and off as part of my polarity test i'm remembering to leave
the switches in the on position i now only need to prove a CPC gets down to the switches themselves
disconnect i'm going to need to re-zero this
okay gonna need to re-zero my leads before now testing up the switches themselves
so picking up a line connection of the switch and the metal work we have a reading of
0.12 i've gone to the actual metal fitting itself 0.12 and i'm probably going on the conduit as well
0.09 proving that the CPC gets to the the frame the conduit and what is effectively the
earthing terminal in reverse there where the brass connection is the earth is connected on the other
side of that so it's where the CPC is connected to that earth terminal move to the next switch
once again pick up a line the earth terminal where the CPC is connected the actual chassis
and the steel conduit itself and we've proved a circuit protective conductor
gets down to the switch and he's earth in all the exposed conductive parts there as well
we're now ready to carry out the insulation resistance test so all my covers have got to go
back on and then we can carry out that test must make sure that our loads don't go back in because
they will need to be removed for the installation resistance test itself so just to confirm we've
proved the CPC gets to the lighting point itself gets a lighting point here as well that it comes
on and off during the polarity test and we left it on ready for the installation resistance test we
proved the CPC also gets down to the switches itself and we've proved in several cases that
we get to the exposed conductive part being the metal boxes and the steel conduit let's get ready
for the insulation resistance test next so the condenser CPC and polarity test has been finished
we're in a position now we're ready to carry out our installation resistance test our earthen
conductor has been connected to the greater mass of earth through the supply authority's earth
connection must remember before carrying out the insulation resistance test that we've removed all
loads so in this case somebody's popped some lamps in for me so they need to be removed
and that we turn off any sensitive electronic devices in this case the RCCB so that needs to
be off and the circuit breaker needs to be off and now we're ready to carry out the insulation
resistance test from inside the consumer's unit both switches have been left on all loads
have been removed and in this case the electronic device has been isolated we're now ready to carry
out the insulation resistance test so ready to set up our Megger MFT in order to carry our insulation
resistance test we set it to the red scale and in this case at 500 volts DC for a 230 volt
single phase installation we're going to short the leads together to prove that they're not
damaged or become disconnected should have zero zero zero so we've got a dead short on our leads
when connected together so we're now ready to carry out the insulation resistance test
clip onto the earth bar no particular order top of the circuit breaker press and hold my test button
i've got a reading greater than 999 megaohms i'll go between the earth and neutral bars
i've got a reading greater than 999 megaohms i'll move the crocodile clip across
and attempt to connect it so we turn between the neutral bar and the top of the circuit break where
the line's connected greater than 999 megaohms must remember now we've got two way switching of
our two lights so we need to walk back into the installation throw both switches goes off go to
the other switch goes on we've now got the other strap in circuit and we repeat the installation
resistance test again before suggesting to our lecturer that we've completed the test on this
circuit let's go again so neutral and earth bars greater than 999 megaohms line to neutral
greater than 999 mega ohms move across and to the top of the line between the earth bar and line
greater than 999 megaohms at this stage we can say that we've completed the installation resistance
test of our two-way switching controlling two lights having done the insulation resistance
test with both strappers in so we've done it twice i hope this video has been some help