so this is a real treat for the channel we're back out with big sexy Matt O'dell and we're
going to try today to go through some of those tests that are going to be required for am2 and
am2s and which one you're going to pick out first that we'll have a go at so in particular we've
got three phase boards so we can do the um earth fault loop impedance yes external earth fault loop
impedance then the PFC yeah so they're really crucial for am2s am2 and well if am2e if you're
doing the experience route as well and we're going to make sure that we don't miss out a
part especially now we've got a three-phase board because of colleges they're working on
single-phase installations aren't they yes yeah so it's a three-phase experience and maybe our
learners don't always get the the hands-on experience with yeah so we've got permission
in order to isolate the supply here and we're going to go through it in the correct process
which means we're going to knock off first of all the breakers before doing the main switch
we're going to remove the cover and then we're going to show first of all external fault loop
impedance and then prospective fault current yes okay so you're knocking breakers off then formula
okay and so we've got the single phase breakers here so we'll start turning those off and so you
can start seeing some lights go off yeah i'll just show that because we're working in the world's
most terriblest place aren't we today look at that okay so yeah whip some off so let's just do the
single phase so the lighting's just gone off in here do you want them to stay on just for now no
no we'll turn everything off we'll do it properly and so then we've got our three phase breakers
so that's a blower a compressor a three phase supply to another board there to the office board
we turned off a lot of the local loads as well so we're not actually got loads of stuff on full
load on for the breakers and then obviously we can do that and so that looks like all the loads have
been taken off yeah and we're going to do the main switch are we now it's quite happy just to turn
the main switch off okay so we're going to get the cover off and we'll look at doing these tests
described at the start of the video okay so the board's off the cover's off and we're now going to
carry out the external earth fault loop impedance just remind me where i'm going to disconnect the
earthing conductor which is here okay so yeah this is the main earth in conductor so if we was not to
disconnect it then we'd be having a problem with parallel earth paths via the likes of extraneous
conductive parts through the bonding and stuff like that so we want to know the
external earth fault loop impedance and so by removing this earth that is just the external
nothing internal okay and we've got an earthing range and i said of TN-C-S so what's the maximum
reading for that for the external on a pme or tncs it's 0.35 ohms okay okay so the earthing conductor
is out we're just going to drop this off all right so yeah we've got the earth out still care
because obviously the bottom side of this is live there is no remote isolator here you might find
an am2 am2s there might be another isolator that you can actually turn this off before
removing it but we're in the real world here so they're now live at the bottom of that switch
and it's red yellow blue and not brown black grey and we're going to set up our instrument now in
order to carry out that external earth fault loop impedance so we've set our megger mft 1730 up to
L-PE and you're gonna do it on the three lead low and that's what you've selected to do it on
we could have done it on high because there's no rcds but you think that this would probably
be the standard practice to get used to matt is that right when we've got so many uh rcds around
um that we go for the low settings okay yeah right okay you want to probe on for me so we can see the
okay so we've got some exposed disconnected earth there so we'll get a good get a nice
good connection onto there and then we've got the neutral terminal here and then we've got
our three phases there so let's just move that one out of the way so again it's an automatic
test so go on to the neutral terminal first and then we'll just probe onto the first line
conductor and as you can see there the machine is automatically detected voltage and it takes a few
seconds because we're on the low uh one yep just fine so we'll persevere and wait for our result
so as you can see there 0.08 that's it we're finished pack up we're ready to go is that
right matt no so that's on one of the phases so obviously there's three phases so we'll
just repeat that same process on the next phase so again because we're going between neutral
and the phase it's detecting a single phase voltage so i think it's about 240 volts in here
of the three readings we take which one are we going to record so it's just the highest
reading okay so we've got remember we've got 0.08 now we've got 0.09 so that's now the highest one
and then we'll probe back on if you notice every time i physically take your probes back off in
the right order exactly the same as we do for obviously supply polarity in safe isolation
yeah right 0.08 of an ohm so okay we've carried out the external fault loop impedance test there
we've got three readings you said you're going to record the highest one in your test paperwork
okay we'll remove the earth and conduct just remind me again we'll remove that
so purely for parallel earth paths we want the external earth fault loop impedance and so that
is the external earth that goes back to the supply transformer good so that is the that is the one
that has to be removed okay we're going to move on in a second to do prospective current yeah
we've reconnected the uh earthing conductor just there because obviously we need all the parallel
earth paths in order to our prospective earth fault and short-circuit current so we're going
to start off by doing our prospective earth fault current i see you've set your instrument there
to two lead high and you're over there is that on PE is it L-PE yeah okay on the actual megger 1730
okay if you're on a probe on we're not expecting this necessary to be a reading we use and we'll
explain that later on in the video when we go through doing between line and neutrals and then
we'll have a little chat at the end and a little rule of thumb will suggest yeah okay okay so get
our good connection onto the earth bar there yeah and again it's on the two lead high automatic test
okay so we're going to go through this and we've got to remember these but not necessarily
worry too much phase one was 2.3 okay that's 2320 amps okay phase two
okay 2130 amps and phase 3 okay and phase three
and two point one okay so we're gonna go on now and do the similar test but this time between the
line conductors to the neutral and then we'll have a little chat about this rule of thumb
is we're going to turn it over so that's now to LL and LN yes and we're on 2 lead does it mean
we now have to change our leads in the back of the instrument as well yeah so so again um
this time we're going to be using these two leads here so in this case we're just going to use the
the red and the black okay so yeah that's a key point to mention because sometimes people change
their leads around in there don't they so we're going to now just be using our two leads yeah so
so again we're just going to probe on to the neutral conductor yeah and then on to the line
conductor and again you can see it's picked up a voltage voltage there as we're testing now then we
come back it should come through a little quicker it has so that's two thousand seven hundred and
twenty amps okay okay again that's phase one so we'll make a note of that we'll go on to phase two
again there's a voltage picked up
okay sometimes you have funny things like that happen where
so that's uh 1972 yeah 70 amps yeah sorry apologize so we suggested throughout that
video there is a rule of thumb when we're doing a three-phase supply we know at college often you're
working on single-phase installations and when you get your am2 am2s am2e it all can be a bit
confusing but we're going to solve that confusion now of all the readings we've got we look at the
highest one on my right and thinking map between our line and neutral and we do mathematically what
with that before we record it so so we simply it's easy calculation just double it okay
now we're always going to take the highest reading and double it through and record it on our test
paperwork because what could we have as a fault in a three-phase system so so what we've done
is we is with the measure the measurements we have took as if it's between sort of earth and
phase and or neutral phase but the worst case would be if it was between phases yes so in
other words a fault was between a couple of line conductors or three line conductors we
get the most amount of fault chrome flowing yeah and therefore we need to prove that our device
can actually clear that fault okay so you'll be looking at the mains end and working out the
prospective fault current of that device but when you're recording on your paperwork you take your
highest reading between your line conductor and neutral and double it through our reading was i
think roughly 2.7 2.7 i'll correct it slightly but it's near enough 2.7 and you double that
in your math suggest that's how many just over five uh five kilo amps five point four kilowatts
thank you very much Matthew yes he's managed to get through on the maths so it's 5.4 kilo amps
would be recorded on my test paperwork okay and that's really important for am2 am2s am2e that
you double that number and people have actually dropped you know i don't suggest failed because
you you get minor marks as you go along that's an easy one not to forget isn't it and again just
just to think about it with with the circuit breakers as well they are rated at often six kilo
amps or ten kilo amps so that does have an effect on on the size of the of the type of circuit
breaker you're using whether it's a six kilo amp or a ten kilo amp yeah and we've looked at that in
other video presentations as well however we're going to carry on a little bit further because
it could be that your am2 and am2s gets developed and your test instrument actually allows you to
carry out between line conductors and will give us that reading so for this part of the video we're
going to carry on and see what the actual short circuit between live conductors is yes yeah so
we've kept the instrument in the same position here but we're actually now going to be testing
between the two line conductors uh let's do that then Matthew so again this time it's important to
use the um this setup that there's the setting with this one and this one here yeah okay so again
it's just set on the two lead high yeah exactly where it were before and it did say didn't we we
saw before it says L and L doesn't it there yeah and so again we just probe on to so this this
time we're going to go between phase one and phase two and you can see there it picks up the voltage
and that's 3280 okay we move okay we'll go between phase two and phase three okay yeah
people are saying this is nowhere near when we recorded we'll just explain that a little
bit in a moment so that's 2790. that's it and then we'll go between phase one and phase three
and that's four thousand one hundred hundred cents now the thinking behind that is obviously we've
got a tncs earthing system here yeah we've got a neutral and earth connected together
and all the rest of it and we'll go into a bit more detail on that in a different video
we've just got to remember that rule of doubling through our readings that we suggested earlier
so thank you matt for showing us that and we believe that's key information done with your am2
and am2s etc so at the end of the video remember to double through the reading that you got when
you tested between the line conductor and neutral the highest value and record it into perspective
fault current as the the qualification maybe develops it might be a case if they
are allowing you actually to measure between two line conductors and if that's the case
obviously you record the highest of those three readings we've got there
it wasn't exactly doubled through was it well it wasn't exactly but yes yeah but it was it was
it is a rule of thumb and again if you want more detail on that in the future we'll produce a video
that can help you understand why that is as always what we've got to say at this point it's been a
long time what we've got to say what are we saying okay i hope this video has been some help we do
you